Cannabis Grow

Compared with the control,Ni110 significantly reduced the hemp emergence rates for the three hemp cultivars,and Ni220 even completely inhibited germination.Unlike Ni stress,Pb1500 had no marked effects on the emergence rates for any of the hemp cultivars compared with the control,however,Pb3000 significantly increased the rates of Guangxibama and Yunma No.1.Both Sb50 and Sb100 significantly increased the germination rate of Guangxibama compared with the control,however,no marked differences between treatments for rates were found for the other two cultivars.Husain et al.also reported a reduction in seed germination of six hemp varieties sown in mine soils and most of the germinated plantlets died one to two weeks after their emergence.Heavy metal and Sb stresses significantly negatively affected the plant height,stem diameter,and the number of leaves of flax.For Cd,Ni,and Pb,most measurements of the plant height,stem diameter,and the number of leaves of the three flax cultivars were significantly reduced by both treatment levels,and the negative effects increased with increasing stress level.In general,compared with the control,Y2I329 was affected only slightly by the different levels of Cd because the three morphological indices of Y2I329 changed the least under Cd stress.Similarly,under the stress of Pb,Y2I329 still showed the best endurance.The plants under high Ni treatment died,and similar negative effects of Ni in flax were also reported by Amna and Syed.The effects of Sb on flax are complex and there is no uniform rule.Plant height was the least affected.The plant height,stem diameter,cannabis grow equipment and the number of leaves of Guangxibama and Yunma No.1 were significantly or slightly reduced by Cd stress compared with that of the control.Similar results were also observed by Luyckx et al..Treatment Cd40 increased the plant height of Zhongdama No.1 but Cd80 significantly reduced it; no significant difference was found for stem diameter and number of leaves.Treatment Ni220 completely inhibited the growth of the three hemp varieties; Ni110 significantly reduced the three morphological parameters for all varieties of hemp.

Pb addition at both levels significantly or slightly reduced plant height,stem diameter,and the number of leaves of all varieties.Sb did not significantly affect the plant height of Guangxibama and Yunma No.1 but significantly increased this characteristic for Zhongdama No.1 compared with that of the control; Sb had no marked effects on the stem diameter of hemp except for the significant reduce in Yunma No.1 by the Sb50.Treatment with Sb50 showed no significant effects on the number of leaves for Guangxibama and Zhongdama No.1 compared with the control but significantly reduced that for Yunma No.1; Sb100 did not significantly affect the number of leaves for Guangxibama and Yunma No.1 compared with Sb50,but notably reduced them compared with the control; Sb100 markedly increased the number of leaves compared with that for Sb50.Cd stress significantly reduced the fresh biomass of HP,but no significant reduction was found for Hongyou No.2 and GGS compared with the control.No significant difference in fresh biomass of the three kenaf varieties was found between Cd40 and Cd80.The addition of Ni and Pb notably or slightly reduced the fresh biomass of all three kenaf varieties compared with the control,and the reduction of biomass increased with increasing metal concentration.Similarly to its effects on flax,Sb50 significantly improved the biomass of all kenaf varieties compared with the control; Sb100 notably or slightly reduced the biomass compared with Sb50 but still increased the biomass compared with the control.Nickel was not lethal for kenaf varieties,however,it significantly inhibited plant growth.Lead was the second most toxic element,especially Pb3000,followed by Cd and lastly by Sb.Concrete is the single most widely used material in the world.Due to the worldwide substantial expansion of our built environment the demand for cement,as a par excellence material used for concrete production,will significantly increase in the near future.For cement production,huge exploitation of Earth’s minerals precedes.Its production is also an energy-intensive process,which contributes to high pollution,especially carbon dioxide emission.Since the increase in global carbon dioxide emissions is unacceptable,a search for other binder alternatives is necessary.

The solution for cement substitution or even its total replacement could be found in industrial by-product pozzolanic materials.Until now,the mostly used pozzolanic material for cement substitution is fly ash that comes from thermal power plants after coal combustion.When fly ashes are mixed with an alkali activator,they form alkali-activated material.This group of materials is comparable in physical and mechanical properties with cementitious materials,but has better durability and can come even at a cheaper price,leaving a much lower environmental footprint.However,these materials still do not have a broad usage in the building construction.The standardization of their solid based materials and activators should be firstly defined.Besides,there are also some disadvantages of the materials that should be solved before they find a broad usage on construction sites.AAMs are brittle or quasi-brittle materials and to move toward more ductile behaviour they need to be reinforced,similarly to cementitious materials.In the field of fibre reinforced materials,natural fibres have attracted a lot of attention in the last decade due to their low production cost and low consumption of energy during their production.Natural fibres are fully biodegradable,renewable resources and globally available.Their tensile strength and E-modulus are comparable to those of synthetic fibres.However,the mechanical properties of natural fibre reinforced composites are somewhat weaker compared to their counterpart reinforced with synthetics fibres.Natural fibres are generally nonhomogeneous,have high hydrophilicity and reduced long term durability in the matrix.One of the most distinctive parameters influencing the properties of the composite is the characteristic of the fibre/matrix interface itself.The quality of the bond is related to the fibres’ surface morphology and topography.To optimise the bond,so far in cementitious composites various chemical treatments on the surface of natural fibres have been applied.In terms of its simplicity and effectiveness,sodium hydroxide treatment could be a viable treatment also in AAMs.There are no results of the hemp fibres’ surface roughness changes and their influence on the pre-and post-peak of the flexural stress–strain curve,after the usage of the sodium hydroxide treatment.However,the enhancement of the fibres’ physical and mechanical properties when the fibres are treated with sodium hydroxide is confirmed.The researches on the alkali-treated fibres show that 5% sodium hydroxide solution treatment of hemp fibres resulted in the fibres’ density increase ,since the treatment cleans the impurities from the fibres’ surfaces.

The treatment also increased the tensile strength and Young’s modulus of the hemp fibres for ca.4% and 28% respectively.Mwaikambo and Ansell tested mechanical characteristics of the hemp fibres after treatment with 0.03%,0.08%,0.16%,0.24% and 0.32% of sodium hydroxide solution.They stated that there was an increasing trend in the tensile strength of the fibres after increasing the concentration of sodium hydroxide.The fibres’ highest tensile strength is reached after the usage of 0.24% of sodium hydroxide.The usage of the concentration of 0.16% of sodium hydroxide solution resulted in the fibres’ highest Young’s modulus.The highest concentration of sodium hydroxide provided the highest fibres’ strain at failure.Alawar et al.showed that data palm tree fibres treated with 1% of sodium hydroxide increased their tensile strength by 300% compared to non-treated fibres.Up to 11%,higher tensile strength of the kenaf fibres after the treatment with 6% sodium hydroxide is achieved in the research conducted by Edeerozey et al..After treating the jute fibres with 0.5% sodium hydroxide solution,the tensile strength of fibres increased by 82%.The sodium hydroxide treatment of natural fibres proved to be very efficient in enhancing fibres’ mechanical characteristics.However,there is no published work on the influence of the sodium hydroxide treated fibres on any group of alkali-activated mortars.According to the authors’ knowledge,there are only the works conducted by Amalia et al. and by Sean et al.where previously treated short natural fibres are used in alkali-activated matrices.In both works,natural fibres were used,but none of them used hemp fibres.Additionally,both studies focused on the alkali-activated pastes,having no aggregates in the matrix.Due to the pure mechanical characteristics and high cost of the pastes they should be upgraded to composites containing aggregate to be considered as building materials in civil engineering applications.Very importantly,the work conducted in this study is the first research dealing with the durability of the natural fibre reinforced alkaliactivated materials in terms of wet/dry cycles.Composites reinforced with natural fibres show comparable mechanical properties tested at an early age as their counterparts reinforced with synthetic fibres.However,after some months,natural fibres degrade in the alkaline environment and their long-term physical and mechanical properties are questioned.Therefore,it is extremely important to estimate the durability of the natural fibre reinforced high alkaline materials.Only with a proof of their durability,they can find a broader usage in the replacement of some traditional fibres and the usage where high energy absorption capacity,mobile grow system resistance to impact- and dynamic loading or prevention of cracking is required.The objective of this research was to study the physical and mechanical properties of hemp fibre reinforced alkali-activated materials before and after wet/dry cycles.The constant change of the relative humidity can seriously attack and destroy the fibre–matrix interface,which reduces the composite’s mechanical properties.With the wet/dry cycles we wanted to simulate a real weather change for the specimens that could be exposed to outdoor environmental conditions and to examine the composites’ properties change.Additionally,the influence of sodium hydroxide surface treatment of hemp fibres on the physical and mechanical properties of fly ash-based alkali-activated mortars was examined.Three different concentrations,i.e.,3%,6% and 9% of sodium hydroxide treatment were applied on fibres and the mortars’ porosity,water absorption,bulk density,compression- and flexural strength,as well as energy absorption capacity under flexure,prior and after the wet/dry cycles,were measured.Besides,the X-ray Powder Diffraction and Thermogravimetry-Differential thermal analysis were conducted on the mortars.

To estimate the fibres surface changes after the treatment,Scanning Electron Microscope and Atomic Force Microscope are used.In addition,the water absorption of the fibres was measured.For fibre reinforcement,primary bast hemp fibres were used Hemp fibres were selected since they are widely used as fibre reinforcement in cementitious materials and have a long cultivation tradition in Europe.Their properties are listed in Table 1.The fibres length and dosage were chosen based on the literature review,as optimal values for a compromise between mechanical properties in hardened state and fresh state properties such as work ability and fibres good dispersion within the matrix.To cut fibres to the length of 10 mm,a small bundle of fibres were taken,measured with a ruler and cut with scissors manually.Due to their hydrophilic nature,the fibres were added to the mixture in water-saturated dry surface condition.They were completely soaked in water for 24 h,taken out,softly squeezed by hand and their surface was wiped with a cloth.The water absorption was measured on 200 g of fibres.From a fibre bundle,fibres were separated manually,and their weight is measured firstly in a dry condition.Afterwards they were put in water and on defined time intervals their water absorption was measured.Even though it could be seen that the fibres’ highest water absorption happens within the first 20 min,they were left in water for 24 h in order to be fully sure that they absorbed maximum water they could.It is measured that the weight of the water-saturated non-treated fibres is 2.3 times the weight of the dry fibres.Due to the ease of application,effectiveness of the fibres’ structure and surface change,availability of the material for fibres treatment,the sodium hydroxide was used for fibres treatment.The sodium hydroxide was also used within the composites’ activator and it was not necessary to additionally provide a new material for fibres treatment.It is true that sodium hydroxide has a negative environmental footprint.However,there is a very minor amount of the sodium hydroxide that could be used for the fibre treatments.In this context,it should be noted that NaOH is the main activating agent for other types of alkali-activated materials bound in a hardened matrix,which has been documented in the publications or even applied in practice.Besides,natural fibres have enormous advantages over traditional fibres.Not only regarding the environmental footprint,but also that they are renewable materials.Therefore,even though they are not used as raw materials,their usage within the composites in the research is still justified.For fibre treatment three different concentrations of sodium hydroxide solution were used: i) 3%-; ii) 6%- and iii) 9% sodium hydroxide solution.To obtain the required sodium hydroxide concentrations,185.57 g,382.98 g and 593.41 g of sodium hydroxide were dissolved in 6000 g of distilled water respectively and left for 24 h to homogenize.Three plastic containers were half-filled with respective sodium hydroxide solutions.Afterwards,in each container 100 g of hemp fibre bundles were added,the containers were filled completely with sodium hydroxide solutions and tightly closed.The containers were placed in a drying oven at 80 ◦C temperature for one hour.

The increase of phosphorus in the minesoil was in line with organic matter content increase.Soil organic matter plays an important role in P sorption as the main constituent of the soil sorption complex which is responsible for binding of anions in the soil material.Phosphorus leaching can be significantly affected by soil adsorption-desorption properties,and it has been shown that application of organic fertilizers could significantly improve the soil phosphorus adsorption capacity.Mengmeng et al.found,that organic fertilization together with mineral NPK increased available phosphorus by 150 % comparing to NPK alone.Application of organic matter is also supposed to improve the soil phosphate availability by promoting microbial activity.The increase in potassium content was slowier than that of phosphorus.During the first three years,this increase was not statistically significant.It was only in 2017 that a statistically significant increase in the potassium content was noted,to the level of 95 mg kg of soil.In the last year of the experiment ,the potassium content reached the value within the norm for this element,ranging from 120 to 200 mg,reaching the value of 175 mg kg of soil.Disturbance to soil by mixing subsoil with topsoi may decrease potassium content.In the studied soil the initial amount of K was very low.On top of that it is known that potassium readily leaches from organic matter as it decomposes.found,that when staw was left on the field,most of its K content was leached during the first month of storage.That can explain the delayed increase of this element level in the course of soil remediation – even though annual potassium fertilization was used.On the other hand hemp is known to take up potassium when the element is not needed and hemp has a lower requirement for potassium than other crops.Most of the absorbed potassium absorbed by Cannabis is concentrated in the stem.

That could explain the finally observed increase of the potassium in the studied soil as this part of the plant is particularly resistant to decay due to the high content of celulose and lignins and could store the absorbed amount of potassium.It is worth noting that the content of phosphorus and potassium reached a value above the lower limit of the norm for these elements only after three and four years of soil rehabilitation respectively,cannabis grow tent despite the annual intensive fertilization with these elements.This confirms the important role of organic matter in the absorption of potassium and phosphorus in the soil.A significant increase was also observed in the case of magnesium content.In the base year,the magnesium content was below normal and amounted to 40.6 mg kg of soil.The level of macro-nutrient gradually increased and in 2017 it amounted to 92 mg / kg of soil,reaching the value of 119.2 in the last year of the study.The standard for the content of magnesium in the soil is from 61 to 100 mg kg.The rate of movement of magnesium in soil depends on soil texture,rainfall and soil pH.It is generally believed that it is easy to migrate in neutral to acidic soil and difficult to migrate in alkaline soil.That suggests that soil conditions in the course of the experiment were in favour to limit leaching of this element and as a result progressive absorption within the organic matter delivered into soil.The manganese content in the tested soil increased in the years 2015–2017 as reclamation was carried out and fell within the norm,which is from 85 to 830 mg.This increase was statistically significant.Also,comparing the base year with 2017,a significant increase in the level of manganese in the studied soil was observed.It has been reported that soil Mn was primarily found in the exchangeable and organic fractions,regardless of soil pH but solubilization of organic acids under alkaline conditions may result in increased complexation of Mn inhibiting its precipitation in the soil environment.It has been also observed that stronger bonding of manganese ions by organic matter was induced by increased soil pH.These previous observations well explain our results showing that Mn content in the soil directly followed changes in the soil pH.The boron content in the soil varied in the studied period.Its level increased significantly from 0.41 mg/kg of soil in 2014 to 0.99 mg/kg of soil in 2017.There was no significant change in the boron level between the starting year 2014 and 2015.Between 2015 and 2016,a significant increase of this micro-nutrient content was observed.Despite the increase,the content of this micro-element was below the standard for Polish soils,which ranges from 2.2 to 7.2 mg kg of the soil.

Although many investigations have been performed with the influence of certain constituents on boron behavior in soil,there is no general agreement on the role they play in B adsorption and desorption.There is general belief that organic matter plays an important role in B adsorption and its availability in the soil.Besides organic matter,also soil pH plays an important role in B behaviour in the soil environment.Gu and Lowe found that B adsorption by humic acids was strongly pH-dependent,being low and relatively constant in the pH range 3.0–6.5,increasing markedly up to a peak at near pH 9.5,and then decreasing at higher pH values.It has been concluded that complexation of B with soil organic matter should only be important at alkaline pH.Our results are in agreement with those previous observations.We have noted the increase of B content in the minesoil together with organic matter accumulation and with soil pH increase.In recent years there has been a development in many areas of plant fibre-based materials ,which has led to an ever-increasing demand for flax scutched fibres,particularly in Europe,which produces 80 % of the world production of flax and hemp.A study conducted by ADEME,the French environment agency,in 2015 predicted that it would be necessary to sow 145,951 ha of fibre crops in France by 2030 in order to meet the demand.This would represent about 1,000,000 tons of straw.In 2018,a total area of only 107,000 ha of textile flax was cultivated in Europe,including 89,000 ha in France.Due to the need for a mild and humid climate and long crop rotations with flax cultivation being repeated on the same land only once every six to seven years to avoid soil depletion and the proliferation of diseases ,the traditional flax production areas are at their maximum production capacity and cannot satisfy an ever-increasing demand for flax fibres.It is therefore necessary to find an additional crop to increase the production of high added value fibres for textile and technical applications to reach the targeted surface of 145 000 ha suggested.In the past,hemp was cultivated for such applications ,in particular for the rigging of sailing ships.A decline in its use during the 20th century led to a sharp decrease in its cultivation worldwide.Hemp cultivation in Europe rose from 15,000 ha in 2013 to 47,000 ha in 2016,of which 16,400 ha in France.A study conducted by FRD and whose results were published in an ADEME report showed that 200,000 ha of hemp is likely to be cultivated in France in the future for different end uses such as fibre,cannabidiol ,shives for building,but this work only investigates the production of long line fibres.

Indeed,unlike flax,hemp is adapted to the climatic and soil conditions of most areas of France and Europe,which allows its establishment over a large geographical area in Europe or in many places in the world such as China.However,the possibility to perform dew retting advantageously is more favourably conducted in mild and humid areas even though it was shown it can be conducted in many different European climates with increased durations for example.The textile flax production zones in Europe where the extraction capacity by scutching/hackling is already present corresponds to the most favourable zone for dew retting of flax and also for hemp.Hemp could also be favourably inserted within flax crop rotations due to its limited fertilizer and pesticide requirements and for its competition against weeds.In the 19th century,harvesting was performed mainly by hand in Europe and in China.In Europe,the first machines to perform fibre extraction using breaking rollers and beaters appeared in 1820.In Eastern Europe,hemp was mainly cultivated for textiles for its long line fibres and countries such as Hungary and Romania developed specific scutching and hackling devices to extract the fibres.These machines,however,required as input,well-retted stems.Water retting was traditionally performed prior to fibre extraction.These processing lines could process whole hemp stalks and very long line scutched fibres could be obtained.However,the resulting fibres were subsequently cut into sections of about 70 cm to be hackled on flax machines.These devices are now very old and have been decommissioned for their dependency on water retting that has been banned in most countries due to its high environmental impact and the risk for humans and animals health.Moreover,the hemp industry in Eastern Europe was labour-intensive,particularly for the harvesting stages and this negatively affects the economic sustainability of traditional value chains.Indeed,the hemp sector has not been able to draw inspiration from the mechanisation of the flax sector and there is currently no complete mechanised hemp harvesting chain for long line hemp fibre production.China,for its part,has invested considerable resources to modernise and recreate an economic sector entirely based on the flax value chain and field retting.This means using flax machinery for the management of the harvesting and fibre extraction.However,this requires that the stem length is shorter than 1 m.In the field a hemp mower,grow lights for cannabis a swath turning machine to homogenise the field retting and an adapted baling system are necessary.

A similar production system proved to be technically feasible in the early years 2000 with the “baby hemp” cultivation in Italy ,where stems were kept short by applying an herbicide when the plant was approximately 120 cm high.In China,manual labour is still used to perform dew retting management and cutting hemp stems in 1 m pieces.If in the past,the numerous attempts to develop hemp harvesters were not completely satisfactory ,suitable hemp mowers are now on the market.However,a machine to cut on the field the mown stems is still not available but this is necessary if flax turning and bailing machinery is to be used.This type of machine is under study and advanced prototypes were tested in summer 2021 with a global success even though improvements need to be completed.With the success of such a prototype,a complete value chain could be created using flax processing lines.Nowadays,hemp fibres for paper pulp,or insulation materials are extracted using hammer mills.This process is very efficient but it damages the fibre and reduces its length.Hemp fibre price,used for technical non-structural automotive applications,is generally much lower than the price of scutched textile flax.However,the mechanical properties of hemp fibres extracted using a hammer mill remain generally low.These fibres cannot be used for load-bearing applications.The possibility to obtain load-bearing grade fibres from hemp would open a complementary market to the one of flax fibres,which is globally saturated and guarantee a higher price than that for the fibres extracted using hammer mills.Ideally,this price should be lower than that of flax long line textile fibres,too expensive for numerous applications in the automotive or other industries.As mentioned above,the old East European hemp scutching and hackling lines are no longer operating,and only flax dedicated equipment are available industrially to extract long line fibres.Preliminary scutching and hackling trials of hemp stems on industrial flax lines were performed by with low scutching yields of long line fibres and high amounts of scutching tows.Vandepitte et al.also used industrial scutching facilities with some of the process parameters changed for hemp extraction purposes with a wide range of European hemp varieties.Higher levels of long fibre scutching yields were globally obtained but this one was dependant on the batches/varieties/levels of dew retting.Following scutching,hackling is generally performed to start the division of technical fibres.During this process tows may also be generated.In hemp stems,the mass of fibres represents,depending on the varieties,about 30–35 % of the mass of the stem.To value the hemp straw and particularly its fibres in the most advantageous way,it is essential to maximise the amount of long line fibres obtained at the end of the extraction process.Main objective of this work is to investigate if hemp could become a source of long line fibre for load bearing composites in complement to the flax ones.To reach this objective,this study proposes to study the long fibre yields obtained at the end of the scutching/hackling process and the quality of fibres that can be obtained.

This has implications for the development of multi—purpose cropping systems of hemp.While low quality fibre can be extracted from plants gro̶wn primarily for their seeds or chemicals derived from inflorescences,the extraction of high-quality textile fibres requires harvesting when no seeds or inflorescences are present yet.Fibres from socalled multi—purpose hemp grown for seed and fibres will thus always contain a mixture of short and long fibres.Plants of increasing height and weight in Fig.6 could represent the same plant at different moments in time,but they can also be considered different plants in a crop at the same time,because with respect to primary  and secondary fibre development,individual plant size is the key factor,not the moment a particular height or weight is reached,or the phenological stage.The stem part that is valuable for textiles,the stem part between the dotted lines in Fig.6,is located higher up along the stem with increasing plant size.It is supported by a stem base of increasing length and weight,which is unfit for yarn production due to the presence of secondary fibres.In short plants  a share of the primary fibres,though fit for yarn spinning,is lost in the stubble,which in practice is 15–20 cm.Once the secondary fibre front surpasses the stubble height  part of the primary fibres are contaminated by secondary fibres.The lower in the plant or the heavier the part of the stem above,the thicker this unwanted fibre layer is likely to be.For reasons of simplification,the inflorescences of the plants in Fig.6 have equal lengths for all plants,it could however be expected that this part becomes gradually longer with increasing plant size.However,vertical grow system no data were recorded.

Mediavilla et al. showed in a dioecious variety that the accelerated development of secondary fibres around flowering first takes place in female plants and later in male plants.This makes sense,when the increasing weight is considered the cause of secondary fibre formation.Male plants on average are longer,but the female inflorescences,where the seeds are gradually filled,are likely to have a higher weight.Bócsa and Karus  also stated that female plants have a relatively higher secondary fibre content than male plants.The proposed conceptual model  also implies that homogeneity with respect to plant size is important when growing hemp for textile uses.In stands with plants of different heights the valuable ‘middle section’ is at variable height,which would cause difficulties in harvesting and processing.The tops of the plants are the comparable parts,not the bottom parts.According to both Fig.4  and 5,secondary fibres above stubble height in Futura 75 can be avoided when the crop is cut when plants are around 1.3–1.4 m and not yet flowering.It is likely,however,that this height is different for varieties,as secondary fibre development is reported to be different between varieties.Reported differences,however,could partially be due to size differences as well.For this reason true varietal differences and differences caused by size differences should be disentangled in future experiments.A non–flowering crop with a height of 1.3–1.4 m can be grown in about two months when hemp is sown at a normal sowing date in April under Dutch growing conditions.However,a subsequent second fibre hemp crop,to compensate for the relatively low stem dry matter yield of the short crop,will be a challenge.For a first sown crop,varieties can be chosen based on excellent fibre qualities,for a possible second crop the variety should be late flowering and it should also have an inherently low secondary fibre content.Further the soil has to be prepared into a homogeneous seedbed again and in dry years irrigation might be necessary to achieve even emergence.Due to the drier summers and shorter days a second crop seems less realistic in Italy than in The Netherlands.However,even when technically possible,it should be economically sound as well,which is doubtful as yet.An advantage of a short crop is that the stems could be processed on existing flax  processing lines as the limited market for high‒quality hemp yarns as yet does not justify the development of specialised hemp scutching and hackling lines.Such systems are dimensioned for flax ribbons with a length usually between 80 and 120 cm,which is about the length of the useful middle section of the stems in our experiment.Earlier attempts in Italy to produce smaller hemp plants by stopping their growth with glyphosate at the desired plant height of 1.2 m  failed due to the environmentally unfriendly production methodology,low yields,low quality,and high costs.Westerhuis et al.,however,showed that normal amounts of scutched long fibres can be extracted from smaller plants.However,these fibres were not hackled.It is likely that the early harvested short crop that we need to avoid secondary fibre formation has relatively fine primary fibres as well.

Fibres have been reported to be finer with decreasing plant size or conditions that in general cause smaller plants,e.g.,earlier harvest or increasing sowing density.Also with respect to the unwanted lignification of the fibres an early harvest before flowering seems best.For future research on this topic it has to be considered that between individual plants of the same height or weight relatively large differences exist in the height of the secondary fibre front.This was not only caused by the fact we measured once every 10 cm stem length; in the field experiment where three cuts were made in every internode a comparable spread was observed.Differences between plants  and,e.g.,wind would co-determine the actual forces  along the stem and thus the mechano perception  inducing fibre formation.Further,we should keep in mind that countering the forces the plant is subjected to,means countering the fresh weight,not the dry weight we measured hence plant fresh weight should be measured as well.To study the effect of weight on secondary fibre formation in more detail,plant weight could be increased artificially.Cannabis sativa L. has been used for more than 6000 years as a source of food, fiber, oil and medicine, as well as for recreational or religious purposes . Cannabis has a very complex chemical composition, with around 540 reported specialized metabolites, such as cannabinoids, terpenoids, flavonoids and alkaloids. The most active of these are by far the cannabinoids, a class represented by more than 100 known terpenophenolic compounds that accumulate mainly in the resin secreted from the trichomes of female plants . Based on its use, cannabis can be technically divided into two distinct groups: marijuana and hemp. Traditionally, marijuana is almost exclusively grown in greenhouses or other controlled environment facilities, being primarily bred for its main psychoactive cannabinoid, Δ9 -tetrahydrocannabinol . On the other hand, hemp serves more as an agricultural commodity, being valued for its fibers and seeds and, more recently, for its nonintoxicating medicinal compounds, notably cannabidiol . From a legal point of view, in most European and North American countries, cannabis is classified as hemp if the crop contains less than 0.2−0.3% THC . Due to their low THC content, hemp and CBD products have recently gained an increased popularity, as their attributed medical benefits are achieved without the “high” effects of marijuana . Consequently, a wide panel of products are nowadays marketed as “full-spectrum” formulas, dietary supplements or CBD-enriched products . The presence of pesticides in hemp crops is a very challenging issue nowadays, not only for cultivators, but also for regulators, consumers or public health researchers .

Many studies have revealed there is no clear relationship between pesticide use and augmentation of cannabis yields, being repeatedly claimed that their role in weed and pest control might be actually unnecessary . Beside their concealed use during cannabis growth, other reasons for pesticide contamination might be related to the spray drift from adjacent crops or assimilation from the contaminated soil; numerous pesticides are environmentally mobile, being carried away by groundwater and rain, whilst cannabis is recognized as a robust and fast growing plant able to absorb pollutants with a great efficiency . Thence, pesticide contamination of cannabis materials has been repeatedly brought into attention . A survey of 389 cannabis products from the state of Oregon found 24 residual pesticides, with piperonyl butoxide as the most commonly retrieved contaminant. Furthermore, 12 pesticides were found in up to 50 % of the cannabis samples collected from central Californian dispensaries . Out of 26 investigated cannabis samples, 84.6 % were confirmed to be positive for pesticides from various classes, such as insecticides, miticides, fungicides or growth regulators . In addition, a multi-screening study testing for 71 residual pesticides in various cannabis products from Italy revealed that amitraz, chlorpyrifos and trifluralin were above the acceptable residual limits set at 0.010 mg/kg . Nevertheless, occupational or non-occupational exposure to residual pesticides has become an important issue due to potential adverse health effects. For example, organophosphate pesticides, mobile grow systems such as chlorpyrifos, malathion, parathion methyl, ethoprophos or coumaphos, have been found to be highly toxic, inducing neurobehavioral and cognitive disorders, teratogenicity, immunotoxicity or endocrinal and metabolic disturbances . Daminozide and paclobutrazol are two plant growth regulators that have been banned in the USA and numerous European countries, due to their carcinogenetic properties; however, both have been found as contaminants in cannabis products . In this light, more and more regulatory agencies are addressing the residual pesticides issue in cannabis products. For example, in the USA, pesticide regulations are specific to each state, mostly due to the fact that cannabis cultivation is still not yet federally legal.

Among the states, California has the most severe requirements, monitoring 66 pesticides, followed by Oregon with 59 pesticides. In comparison to these, Canada has set wider and stricter controls of pesticides in cannabis products, demanding testing for 96 pesticides, with limits of quantification usually lower than those set in the USA . From a processing point of view, cannabis derived extracts are frequently obtained using CO2-supercritical fluid extraction followed by winterization , decarboxylation , distillation and, optionally, a chromatographic-based method for the isolation of specific cannabinoid compounds . For instance, CBD purification is mostly achieved by recrystallization, conventional chromatography with solid stationary phase or liquid-liquid chromatography. LLC, better known as centrifugal partition chromatography and counter current chromatography , is a preparative separation technique where the two phases of a biphasic solvent system are used as the mobile and stationary phase. One of the two phases is kept stationary inside the column with the help of a centrifugal field, while the other one is pumped through the column . In this sense, LLC enables high column loading, while expensive solid stationary phases and time intensive column packing procedures are not required. In addition, the almost limitless variety of possible biphasic solvent systems and easy preparation of tailor-made solvent systems make LLC a very flexible, scalable, as well as selective separation technique . Taking advantage of these benefits, Hazekamp et al. showed that CBD can be separated by CPC using n-hexane/acetone/acetonitrile 5/2/3 as a biphasic solvent system, with the acetonitrile-rich phase as the stationary phase . To this end, a considerable attention has been paid either on the large-scale purification of CBD by LLC or the ultra-trace detection of residual pesticides in cannabis products, but not to the removal of the contaminating pesticides. Therefore, the aim of this study was to establish a systematic computer-aided approach for the selection of biphasic solvent systems for the simultaneous purification of CBD from hemp extracts and removal of specific-contaminating pesticides. In this sense, a predictive thermodynamic model was used for solvent system screening, guiding the user toward the design of tailor-made solvent systems for the isolation of pesticide-free CBD from a particular hemp extract using LLC. Two experimental protocols were followed in the shake-flask experiments, depending on the purpose. For the initial screening of the partition coefficient of CBD in different solvent systems, 5 mg of hemp extract were added to upper and lower phases of preequilibrated solvent systems and placed into a 20 mL vial. Then, each phase was analyzed by HPLC-DAD . Once the three solvent systems were selected, the six pesticide mixes and CBD standards were combined together and a stock solution, in which CBD and each pesticide had a concentration of 50 ppm, was obtained by a proper dilution in acetonitrile. 20 μL of the stock solution were added to 20 mL of each of the three selected solvent systems, affording a nominal concentration of 50 ppb of each solute. Afterwards, 1 mL of upper phase and 1 mL of lower phase were taken, evaporated to dryness, re-dissolved in 1 mL methanol and analyzed by LC–MS/MS to determine the concentration of each analyte in the phases.

These functional properties are the result of the vegetal aggregates employed in the formulation,whilst mechanical strength is provided by the presence of frame.Numerous studies have been carried out on defining and understanding the properties of the material,or optimising the formulations used.A number of recent studies have looked at the durability and long-term behaviour of these insulators,but the accelerated aging processes are much too short or overly severe in comparison to real-world conditions of use,such as the application of freeze–thaw cycles.However,lack of knowledge about the evolution of the properties of plant-based concretes over time is a barrier to the development of these materials.Indeed,the lack of guarantee as to the durability of the desired properties over a given period of time does not inspire confidence in users,architects or insurance companies.It is for these reasons that a study is conducted on the durability of hemp-based concretes,with the aim of identifying the mechanisms which cause the functional properties of the material to change.However,to date,there has been no study done of the change over time observed in the plant aggregates on their own,although it is these particles which are responsible for a large proportion of the properties for which the material is used.In order to understand the mechanisms of aging of plant-based concretes,it seems essential to understand the behaviour of the particles in bulk over time.With a similar chemical composition,made up of cellulose,hemicellulose and lignins for the most part,it is possible to draw inspiration from the numerous studies examining the durability of wood.

Durability studies on wood have produced standards which guarantee quality and users’ expectations over a given period of time,mobile vertical rack in set usage conditions and with an amount of maintenance.Depending on the application,specific wood species are chosen according to the applications and the conditions of use.Various aging factors are applied on wood in these studies,such as immersion in water for periods from 10 days at 60 and 90 °C to 8 and 2000 years in natural conditions,variations of relative humidity during 20 days to one year,exposure to UV aging until four weeks or natural aging without protection during several years.Therefore,depending on the study in question,the aging conditions are very different in terms of environment or exposure duration.Whatever the protocols used,the functional properties are monitored over time,namely mostly mechanical and/or hygroscopic properties,but also acoustic properties.Overall,aging leads to deterioration in the mechanical properties and to an increase in water sorption capacity.Other parameters which characterise the microstructure of the material are also studied,such as porosity,swelling,or variations in weight of the materials.The variations of functional and microstructural properties are often explained by a change in the chemical compositions of the wood,usually due to the degradation of the lignin or hemicellulose.These chemical degradations may result from photo-oxidation or thermo-oxidation reactions,but above all,from the action of micro-organisms which can grow on lignocellulosic materials in high humidity conditions.Indeed,the micro-organisms use the cellulosic materials as a nutrient,and they may,selectively or otherwise,attack pectin,lignins,hemicellulose or cellulose.These micro-organisms are present in the air and in water,but also in the plants as they grow.Indeed,in order to separate the fibres from the stalks more easily,the material may be retted for a time,enabling the micro-organisms to consume the pectin which binds the fibres together.Therefore,such retting impacts upon the properties of the materials.There are various tests of resistance to the growth of micro-organisms,placing the plant materials inoculated with moulds in conditions of high hygrometry,as for example 26 °C and 85 and 95% RH,or 20 °C and 70% RH.

The result of an attack by micro-organisms is a loss of mass of the materials,which can lead to structural alterations which modify the functional properties,such as mechanical properties.In view of these results,three environments are chosen in this study to assess the durability of hemp aggregates used for vegetal concretes.The second one is an accelerated aging imposing variations in humidity.The relative humidity varies from 40% RH to 98% at a fixed temperature of 30 °C.Indeed,in the normal conditions of use of hemp concrete,unlike wood,hemp shiv should never be exposed to direct UV light or to liquid water.This temperature favours the development of microorganisms,which has been identified as a significant degradation factor.Finally,a harsher,outdoor aging process is used.The objective of this article is to identify the mechanism by which hemp shiv ages in the presence of moisture.The potential evolution of the functional properties of the material  is characterised and linked to the micro-structural changes  occurring in the different environments.The acoustic properties are measured using a Kundt tube.Two types of properties are obtained: the acoustic absorption co-efficient α and the transmission loss TL.The acoustic absorption co-efficient is the proportion of sound energy absorbed by a material.It is expressed for values ranging between 1  and 0.The transmission loss  represents the sound insulation provided by a material.3 measurements are taken for each batch of bulk shiv over a frequency range [250–2000 Hz].At A0,the batches contain 40.7 g of hemp shiv,to obtain a controlled density of 130 kg·m−3 in the volume of the sample chamber.The different batches are aged and reused for the acoustic measurements.The hydric behaviour is determined on the basis of the water vapour sorption isotherms using a DVS machine.A few granules representing a few tens of mg are suspended in a microbalance within a sealed thermostatically controlled chamber at 25 °C.The schedule for the DVS is set to start at 0% RH up to 95%.A given relative humidity is applied until the weight change of the sample is less than 0.0005%.min−1 or during 12 h if the weight is not stabilised.Sorption isotherms are produced by plotting mass change against relative humidity  and illustrate the water vapour sorption capacity as a function of the relative humidity.The overall sorption behaviour across the whole range of relative humidity values is simulated using the GAB model,as described in an earlier study.

Depending on the kind of porosity,it may be open and accessible for measurement,open but not accessible to measurement,or closed.With a pore size in the millimetre range,the interparticle porosity,represented in grey in Fig.3,is always open and accessible.On the other hand,the intraparticle porosity may contain closed pores and pores not accessible to the measurement.For simplicity’s sake,no distinction is drawn between intraparticle porosity which is closed or open but not accessible; both are denoted by Φintra_closed.This category is randomly represented in dark green in the diagram.The open and accessible intraparticle porosity is called Φintra_opened.By combining different techniques,it is possible to quantify the different volume fractions corresponding to the vegetal part or to each type of porosity.In all cases,these volume fractions are expressed as a function of a volume of bulk shiv.The bulk density ρ of the hemp shiv is the ratio of the mass of a batch of bulk hemp shiv to the volume it occupies in unstressed conditions.The density of the plant cell wall ρcell wall is an intrinsic value of the material,which depends on its chemical composition.In this case,the vegetal cell wall is expected not to contain any porosity.The volume corresponding to the vegetal cell walls of the material is measured by introducing a fluid into the pores in the material.Knowing the mass of the sample introduced,the density of the vegetal part can then be calculated.To measure this density,the hemp shiv is ground to a powder of grain size less than 500 μm in order to eliminate the porosities of the vegetal cell walls.The volume of the powder is then measured using a helium pycnometer.New energy storage systems have been continuously developed for replacement of fossil fuel to meet global energy requirements in the last decades.Multifunctional materials with an integration of structural and non-structural functions create new areas in the advanced energy storage system,such as structural super capacitor,which can maintain its capacitive function under a mechanical loading.At least two components of structural super capacitor are required to satisfy structural function such as structural electrode and structural electrolyte or separator.Maybe the structural electrolyte is more challenging,because that it must combine high ionic conductivity with good mechanical strength.However,it is generally known thationic conductivity and mechanical performance have an inverse relationship,because ionic conductivity requires pore structure for ion migration but strength needs compact structure.

A bicontinuous structure of electrolyte is designed to keep a good balance of performance,where one phase provides ionic conduction and the other phase is responsible for mechanical properties.The earliest structural electrolyte is polymer resin as structural component and ionic liquid based electrolyte as ionic conductive phase because polymer-based electrolyte has good mechanical properties,long lifetime,short charging time and wide potential window.Generally,polymer resin may contain of epoxy resin with more than two oxirane groups,polyethylene oxide or polyethylene glycon,while ionic liquid phase can combine several types of cations and anions.Shirshova et al.prepared ionic liquid-epoxy resin composites to obtain a structural electrolyte with ionic conductivity of 0.8 mS·cm−1 and a Young’s modulus of 0.2 GPa.Cole et al. reported polymer electrolyte-based stretchable super capacitors with a specific capacitance of 5–10 F·g−1 and mechanical stress of 0–3 MPa in suit microtensile characterization.Greenhalgh et al.fabricated structural super capacitors with epoxy which exhibited a compressive strength of 19.44 MPa and a specific capacitance of 4.5 m F·g−1.A novel structural super capacitor based on ionic liquid-polyester resin had a specific capacitance of 2.48 F·g−1,an equivalent series resistance Rs of 370 Ω and an in-plane shear strength of 102.4 MPa.However,the polymer electrolytes tend to have a low specific capacitance,and as the electrochemical property improves,the mechanical performance typically decreases,vice versa.Thus such polymer electrolyte may not well solve the challenge of balancing the electrochemical and mechanical properties of structural super capacitor.Recently,another kind of structural electrolytes were reported for building applications,cement as structural component and aqueous electrolyte as second phase.Normally cement as gel materials has high mechanical strength as well as prosperous pore structure.The pore size of pore structure can be divided into b20 nm,20–100 nm,100–200 nm and N200 nm,vertical grow rack and the amount of macropores in cement is N90% of total pores.As hydrated radius of aqueous electrolyte is generally smaller than 0.5 nm,such pore structure in cement is large enough to be filled with aqueous electrolyte to form structural electrolyte as well as to provide channels for ions passing,which is similar to the effect of pore size on the performance of electrodes.Zhang et al.reported a cement-based structural electrolyte with a specific capacitance of 10 F·g−1 and a compressive strength of 9.85 MPa.

Subsequently,Xu et al.fabricated a structural electrolyte based on geopolymer with a compressive strength of 33.85 MPa and a specific capacitance of 33.4 F·g−1.Ma et al.also reported a combining magnesium phosphate electrolyte with a compressive strength of 24.5 MPa and a specific capacitance of 40.9 F·g−1.Therefore,combining cement with aqueous electrolyte is a promising approach to develop structural electrolyte due to its low cost,structural integrity,chemical stability and good compatibility with structural component.Thus pore structure has an important role in the performance of cement-based structural electrolyte.The porosity and pore inter connectivity are likely to play critical roles in characterizing the pore structure of the structural electrolyte.Hemp fiber has been chosen to alter pore structure of cement based structural electrolyte in this work.There are two reasons for choosing the hemp fiber as pore forming agent.The first reason is that unique interconnected partially graphitic carbon nanosheets with significant volume fraction of mesoporosity has been created from hemp fiber,which exhibits excellent electrochemical performance in super capacitor and sodium ion battery.The other reason is that a large content of hemp fiber often leads to considerable number of macropores,which can result in forming interconnected pore structure in cement.Thus the effect of pore structure of structural electrolyte on the performance of structural super capacitor was investigated by adding various volume fractions of hemp fiber in this work.Typical SEM image of the structural electrolyte containing 15 vol% of hemp fiber is shown in Fig.3a and the corresponding EDX analysis result is listed in Fig.3d.It is clearly seen that hemp fiber is nonuniformly distributed in the matrix due to the large fiber content and non-homogeneous mix.Due to the presence of hemp fiber seriously interfering with image processing,careful selections of parts of SEM images without hemp fiber were used to measure the two parameters of pore structure,including porosity and pore connectivity,like Fig.3b.Image analysis technique is employed to process the SEM images to quantitatively characterize pore structure of the structural electrolyte with hemp fiber,like Fig.3c.

The wett ability of the surface is controlled by the surface chemical composition as well as by the morphology of the mic-structure.Surfaces with a similar chemical composition may have different wett ability behaviour due to the surface topology.In this study,the surface of hemp shiv underwent micro-structural changes via deposition of an organo-functionalised silica coating.Ethanol diluted sol series enhanced the surface roughness of the hemp shiv.At higher HDTMS loading,undiluted coatings  lowered the surface roughness of the shiv which could explain the reason for lower contact angles compared to diluted coatings.Sol A-1 and sol A-5 have HDTMS molecules that are not fully hydrolysed and being deposited onto the membrane as a flat thick film as seen in Fig.6b.The reduced surface roughness can be attributed to the extra HDTMS molecules on the coated surface.Since an organic-inorganic hybrid coating was used,the ratio of TEOS: HDTMS was critical to control the roughness of the coatings resulting in variable water repellent properties of the coated hemp shiv.Most of the coatings enhanced the surface roughness except sol A-1 and sol A-5.These coatings had smooth surfaces with cracks which could explain the lower contact angles even though it had the highest loading of hydrophobic agent.It was observed that the TEOS: HDTMS molar ratio in the coating formulations affected the hydrophobicity of the coated hemp shiv.From Fig.3 it can be seen that varying the concentration of HDTMS in the formulations affects the water contact angle.When TEOS: HDTMS was 1: 0.01 corresponding to 0.5 wt% HDTMS,the contact angle was below 100◦ which suggests the concentration of the hydrophobic agent was too low to provide sufficient level of hydrophobicity.

The best results were obtained with TEOS: HDTMS ratio 1: 0.02  with contact angles up to 118◦.However,when the TEOS: HDTMS ratio was increased to 1: 0.06,the hydrophobicity was decreased for the undiluted sol coatings.These results can be explained by the combined effect of surface roughness and energy.TEOS is hydrophilic whereas HDTMS is hydrophobic and changing their molar ratio can affect the surface roughness and energy ofthe coated material.Increasing the HDTMS concentration would reduce the surface energy.However,best trimming trays the surface roughness can be reduced if the HDTMS concentration is high enough as the extra silane fills the inter-particle gap.Similar results have been reported in different coating systems.Although sol B-7 coating enhanced the surface roughness,it had developed cracks which lowered the water contact angle to 98◦.The presence of surface cracks arising as a result of shrinkage after drying the coated shiv is a significant factor to be considered when hydrophobic properties are concerned.The hydrophobicity of modified hemp shiv can be compromised as the water molecules can penetrate through the cracked coating wetting the bulk of the material over time.Therefore,sol-gel coatings chemically modified the surface of hemp shiv which overall improved the hydrophobicity of the material.The high water repellence can be attributed to the long alkyl chains of HDTMS that provide high hydrophobicity.The chemical composition of hemp shiv is mainly composed of cellulose,hemicellulose and lignin,which altogether contain a large percentage of oxidized carbon in their structure.Hydroxyl groups are known to contribute towards majority of the carbon-oxygen bonds in bio-based materials.The XPS data confirmed that the sol-gel deposition on hemp shiv significantly altered the surface chemistry.The surface carbon content of the coated hemp shiv decreased by 41.28%.On the other hand,the oxygen content increased by 26.51%.

This change in C/O ratio and increase in surface oxygen concentration can be attributed to O CH3 bonds present in the polysiloxane coating on the surface of the sol-gel coated hemp shiv.Moreover,the decrease in the surface carbon concentration of the sol-gel coated shiv can be attributed to the masking effect of the polysiloxane coating which reduces the detectability of surface cellulose and hemicellulose.The C1s high resolution XPS spectra indicate that the surface has been modified by the silica based coating that led to disappearance of C3 and C4 components of the C1s peaks.A shift in the binding energy of C2 component  was observed along with the decrease in the intensity ofthe C2 componentfor the sol-gel coated sample.This shift indicates the presence of a carbon atom linked to an oxygen and silicon atom.It has also been shown that curing above room temperature drives the dehydration reaction at the adsorption sites between hydroxyl groups of the cellulose and the silanols forming Si O C bonds.These bonds are formed by the linkage between polysilanol network with the cellulose hydroxyl groups via polycondensation as illustrated in Fig.9.The increase in the intensity of C1 component for sol-gel coated sample from 48.01% to 91.09% indicates the presence of C H and C C bonds from the HDTMS hydrocarbon chain.Hemp concretes are the most widely used biobased concretes in France.As an example,VICAT,one of the European leaders in the production of building materials,has developed a construction system composed of hemp shiv and Natural Prompt Cement.Although construction rules exist for these materials,their growth is still limited by the lack of knowledge and high variability of the performances of biobased concretes,especially for their mechanical properties.In addition,even if it is not the main performance expected,they still require sufficient mechanical resistance to be unmolded,transported onsite,and handled.Several parameters,such as setting delays of the binder or potential degradation of plant particles have been identified to explain their mechanical weakness.

Moreover,on existing buildings,problems of powdering of the materials in the core have been observed even when using binder/vegetal couples validated by the construction rules.Currently,while cementitious binders are well characterized,the physico-chemical mechanisms that affect the setting of the binder in biobased concretes have not yet been well understood so far.The modification of the hydration of the binder is related to the extraction of compounds from the plant aggregates which are not chemically inert,contrary to the mineral aggregates of conventional concretes.As a consequence,empirical testing is currently used to assess the compatibility of specific biomass particles and binders couples.These tests validate the performance of a biomass batch and binder couple at a given time,but do not consider the important variability of plant chemical composition and micro-structure.The latter depends for example on plant species,genetic material  and environment of its growth,but also on their transformation process.This lack of knowledge about the robustness and performance of plant-based concretes is the main obstacle to their development.Hemp crete offers a means of achieving the rules set by the French national environmental regulations,which applies since 2022,but also of improving technical aspects of the concrete used in construction today.When dry,hemp has a very low bulk density of around 110 kg.m− 3,meaning that hemp-based concrete is lightweight.It is an effective insulation material with good hygrothermal and acoustic properties.It has low thermal conductivity  due to its porosity and low density.That porosity and the hydrophilicity of hemp create a buffering effect that regulates the humidity within the concrete.Hemp crete is also interesting from an ecological point of view,as it requires no pesticides and cleans the soil,leaving it in a better state than before.Furthermore,it reduces the distance and time of transport from the source to the building site since it uses materials cultivated locally.Finally,the plant particles in the hemp concrete act as a CO2 trap during the lifetime of a building.

Existing studies on bio-based concretes formulated with mineral binders and vegetal aggregates from different origins and chemical compositions showed that the properties of materials are disparate.As an example,for identical formulations,the use of nine types of hemp shiv from different sources leads to differences in compression strength by a factor of 5,while the impact on thermal conductivity is smaller.These results are attributed to the particle size distribution of the bio-resources,their water absorption and chemical composition and to the lixiviation of vegetal compounds.About impact of vegetal components on the hydration of binders,some studies highlight the modification of the mechanisms and kinetics of hydration of mineral binders by vegetal components.Indeed,during the processing of plant-based concretes,vegetal compounds,such as polysaccharides and polyphenols extracted in the fresh concrete mixture,interact with the mineral phases.Some of these extracted compounds can slow down or even completely inhibit the setting of the binders.These results,observed with various vegetal concrete formulations containing wood,hemp,miscanthus,corn or sunflower,depend on the selected plant-mineral binder couple.A correlation can be drawn between the biochemical nature of raw plant materials,including the plant cell wall quality,the composition of the leachates,and the mechanical properties of bio-based concretes.On a different scale of analysis,an interfacial transition zone  is observed around the vegetal particles.The ITZ is a gradual transition region where the composition and micro-structure of the binder matrix are affected by the presence of the aggregate particles.This impacts on the physical properties,mechanical properties,functional properties  and durability  of vegetal concretes.In this study,a newly implemented protocol is set up using a hemp pellet put into a cement paste.The halo of less hydrated material created around this pellet is monitored using image analysis.Different analysis methods  have been used to characterize the hemp crushed for the pellet and to analyze the ITZ and the hydrated matrix.The cement used to make up the cement paste is a Portland cement CEM I 52.2 R,trimming tray kept at a temperature of 20 ◦C in a sealed plastic bag.To reduce bleeding in the cement paste,KELCO-CRETE DG-F from BASF  was used.This is a water-soluble biopolymer used in hydraulic cementious systems as a viscosity modifying agent.The characterizations of hemp were performed on sample dried at 50 ◦C for at least 2 days,in accordance with the RILEM recommendations.The hemp used for the experiments has a bulk density of 116 kg.m− 3.Its particle size distribution is extremely heterogeneous and the initial rate of absorption  is 135 %.

A ThermoFisher Scientific iS50 device with Attenuated Total Reflection  mode was used for Fourier transform infrared spectroscopy measurements.The spectra were acquired from 500 to 4000 cm− 1,with a digital step of 0.5 cm− 1  and on average,with 32 successive scans.Spectra were corrected between 1900 and 2400 cm− 1 to remove CO2 contribution,with an automatic baseline.The data were processed using OMNIC® software.It was decided to differentiate the internal face  from the external face  of the shiv to see its influence.X-ray diffraction  analysis was performed on a Brüker D8 Advance device directly on a pellet of constant size,which was made of 0.1 g of hemp ground and compressed at a pressure of 10 tons.After drying at 50 ◦C,the pellet was removed from the oven and tested as soon as possible  to reduce the impact of water absorption due to air exposure,which can affect the results.The data were analyzed using Specta Software.In order to study the ITZ between the hemp and the binder,the experiments were conducted on hemp pellets in contact with cement paste.The protocol was adapted and improved to tackle the issues encountered in previous studies like robustness,repeatability and accuracy,to monitor the formation of the ITZ from the moment the binder is finished being poured.The compositions of the cement pastes used in this study are presented in Table 1.The overnight data acquisition showed the formation of the ITZ.First,the pellet absorbs the water in the cement paste.Then it begins to dry,and the ITZ forms from its outer edges after approximately 5 h.The cement paste slowly becomes lighter in the vicinity of the pellet.The extracts of hemp seem to be released as soon as the pellet is placed into the cement paste,and percolate around the pellet over a distance of few millimeters.Then,the paste begins to set from the edges of the mold to the pellet,and the halo appears due to the presence of chemical components which delay or interfere with the setting.FTIR spectra of cement  show that while similarities can be found between the ITZ and the hydrated matrix in terms of the micro-structural composition,like the presence of portlandite and O–H bending in cement hydrates,certain components are also in common with the anhydrous cement,like the presence of gypsum,alite,belite,and anhydrite.FTIR mapping shows the evolution of the area under the band relative to portlandite at 3640 cm− 1,with a base line from 3660 to 3600 cm− 1.Portlandite is chosen because it partially reflects the hydration of the cement.The color scale of the mapping ranges from blue,showing a very small vibration band area,through green,to red,highlighting a larger vibration band area.The lower part of the map corresponds to the area near the hemp pellet,as evidenced by the observation.

In order to monitor the effects of reformulation and heating treatment on the lipid oxidation of beef burgers, lipid oxidation was measured in all samples, before and after cooking.Significant differences  were obtained with the addition of GEs, in both raw and cooked samples.In raw samples, burgers reformulated with chia oil  registered higher TBARS values  than the control sample, being burgers with the highest replacement level  which showed the highest  TBARs values.In fact, BCh50 samples showed 3.5 times more oxidation than the control sample.Burgers reformulated with GE with hemp oil  showed similar TBARs values   than control.This fact was in concordance with several authors who reported that the use of GE elaborated with vegetable oils as animal fat replacement in meat products might be complex due to the high oxidation susceptibility of these unsaturated oils.The differences in the lipid profile of the oils, the content of polyunsaturated fatty acids, and the temperature used to generate oleogels or gelled emulsions could affect the MDA levels.It must be noticed that TBARS values in burgers reformulated with GE elaborated with amaranth flour and hemp oil  as well as the burgers reformulated  with GE elaborated chia oil  were below the malonaldehyde limit for acceptability reported by Trindade, Mancini-Filho, and Villavicencio   for loss of sensory attributes and perception of oxidation by consumers.However, it is important to highlight that cooked burgers reformulated with GE elaborated with amaranth flour and chia oil showed values above the threshold limit for consumer acceptability.The influence of the addition of GEs on sensory attributes of raw beef burgers is shown in Table 8.Relevant parameters affecting consumer purchase were measured, such as “color”, “rancid aroma” and “product appearance”.

Panelists did not detect differences between control and reformulated burgers  for any of the three evaluated parameters.This result agreed with the instrumental color parameters,hydroponic grow tent where L*, b* and h* values had no differences  between samples and the rest of color parameters  showed small differences which were statistically significant but without practical significance.In the case of cooked samples, juiciness, chewiness, fat sensation, graininess and general acceptability were evaluated.The only attribute that showed differences  between samples was graininess: BCh25 and BH25 showed the highest  score  without statistical differences between them , while control sample had the lowest.These results agreed with the instrumental analysis since textural analysis revealed only differences in cohesiveness between some samples.For the preference test, control sample  and BH50  were the most chosen.It has to be mentioned that the information about the nutritional improvement  achieved in reformulated burgers was not communicated to panellists and that could be relevant and affect their sensory attractiveness.Hemp  is a widespread herbaceous plant native from Central Asia that belongs to the Cannabaceae family.This plant could be considered as one of the first crops because it is thought that it was cultivated in China 8500 years ago.Hemp has been traditionally cultivated with industrial, medicinal and food purposes.Its fibre was obtained from stems, specifically from the phloem, and it has been widely used, especially in the shipbuilding industry.Female flowers were useful because of their pharmacological properties, and seeds were used mainly as food.Hemp phytochemistry is quite complex and cannabinoids are its most distinctive compounds.They are produced almost entirely in glandular trichomes, which are commonly located in the bracts of female flowers.Nevertheless, other parts of the plant, such as seeds, could contain a small quantity of cannabinoids , which is subject of regulation in different countries of the world.

The most important one is Δ9 -tetrahydrocannabinol , due to its psychoactive properties, and only varieties with low Δ9 -THC content can be cultivated.Nowadays, the consumption of hemp seeds and derivative products is increasing.Whole hemp seeds are used as a raw material, but could be consumed as food as well, and hulled hemp seeds are commonly marketed as functional food.Hemp seeds contain large amounts of fibre, fat, and protein, at 27–40, 25–35, and 18–28 g/100 g, respectively.They contain significant amounts of linoleic acid, which represents 50% of total fatty acids, 16–19% of α-linolenic acid, 12–17% of oleic acid, and other minor fatty acids, being remarkable the presence of γ-linolenic acid.In addition to nutrients, hemp seeds contain bio-active compounds which confer a biological potential, such as antioxidant, antimicrobial and cytotoxic properties.Chen et al. attribute some of these bio-active properties to phenolic compounds, the main being lignanamides, such as cannabisins.The studies about mineral elements in hemp seeds are scarce, but Callaway  and Mihoc et al. reported an interesting content of some of them, such as phosphorus, potassium, magnesium, calcium, iron, zinc, manganese, and copper, which are essential dietary elements for mammals and are involved in many physiological processes.Mineral element bioavailability could be compromised by different anti-nutrient components in foods, such as phytates and oxalates, which are present in hemp seeds.Phytic acid is the main storage form of phosphorus in seeds and it can form insoluble complexes with some cations, such as calcium, magnesium, iron, and zinc.The chelating capacity of phytates is especially damaging in the case of iron and zinc, and their deficiencies constitute a significant public health problem.The absorption of calcium of plant origin is impaired by the presence of oxalic acid, which promotes the formation of insoluble calcium oxalates.The objectives of this study were to determine the mineral element content of different varieties of whole hemp seeds and commercial hulled hemp seeds, as well as the phytate content, which is closely related to the mineral element bio-accessibility.Phytates were determined by an indirect iron  complexometry with sulfosalicylic acid like an indicator of the titration endpoint, according to Romero–Aguilera et al..The extraction was carried out under magnetic agitation for 90 min from 2 g of sample with 40 ml of HCl 0.4 M, which contained Na2SO4 5%.

The resulting suspension was centrifuged at 1890g during 8 min, and the supernatant was filtered and made up to 50 ml with the extraction solution.After that, 20 ml of the extraction solution, 20 ml of FeCl3 0.02 M , and 20 ml of sulfosalicylic acid 20%  were added to 25 ml of the extract, and the mixture was made up to 100 ml with distilled water.Blank was prepared in the same way, but 25 ml of the extraction solution were used instead of the extract.The solutions were heated for 15 min in a boiling water bath and then they were cooled in an ice bath.One aliquot of 20 ml was pipetted together with 200 ml of distilled water and 1.5 g of glycine were added.This solution was heated at 70 ◦C and titrated with EDTA 10 mM while still warm until the solution turned yellow.All the volumes obtained from the titration of the samples and standards were subtracted from the blank value, obtaining the amount of EDTA equivalent to the complexing activity of.the phytates in the sample.For quantification purposes, a calibration curve was built using a commercial phytic acid standard.The analyses were performed in triplicate and the results were expressed as g of phytic acid equivalents /100 g.The results of mineral element analysis of both whole and hulled hemp seeds are shown in Table 2.Regarding macroelements, sodium was the least abundant, with an average value of 2.75 and 1.41 mg/100 g in whole and hulled hemp seeds, respectively.All the samples contained less than 5 mg/100 g.On the other hand, phosphorus was most abundant one, with an average value of 871.2 and 1099.5 mg/100 g in whole and hulled hemp seeds, respectively.Phosphorus content was lower in whole hemp seeds, being the maximum value 928.1 mg/100 g, which corresponded to ‘Tiborszallasi’ variety.Potassium content was also high in hemp seeds, especially in hulled seeds, which contained on average 919.5 mg/100 g, while the average content in whole hemp seeds was 569.6 mg/100 g.Potassium ranges were wide, from 311.5 to 713.6 mg/100 g in whole hemp seeds and from 778.8 to 1067.7 mg/100 g in hulled hemp seeds.Magnesium content was also higher in hulled hemp seeds, in which ranged from 482.3 to 934.2 mg/100 g, with an average value of 696.9 mg/100 g.However, cheap grow tents the range in whole hemp seeds was very narrow and there were not statistically significant differences between the eight analysed varieties.The average magnesium content in whole hemp seeds was 383.4 mg/100 g.Calcium content, on the contrary, was higher in whole seeds, with an average value of 175.6 mg/100 g, being half in hulled hemp seeds.

In respect to microelements, most of them were more abundant in whole seeds.Iron was the major microelement in whole hemp seeds, with an average content of 8.04 mg/100 g, closely followed by zinc and manganese, whose average contents were 7.94 and 7.48 mg/100 g, respectively.Zinc was the most abundant microelement in hulled hemp seeds, with an average content of 9.81 mg/100 g.Iron content in hulled hemp seeds were slightly lower than in whole seeds, 7.83 mg/100 g, while manganese content was much lower, 5.18 mg/100 g.Copper content was lower than the other microelements, on average, 2.30 and 1.48 mg/100 g in whole and hulled hemp seeds, respectively.Among the analysed varieties, ‘Carmagnola’ variety stood out because it had the maximum values of sodium, calcium, manganese, iron, and zinc, and the minimum values of magnesium and phosphorus, and the ‘Kompolti’ variety stood out because it had the maximum values of potassium and copper, and the minimum values of calcium, manganese, and iron.Regarding hulled hemp seeds, there were a wide variation among the different brands.As it has been said previously, few studies on mineral elements in whole hemp seeds are available, so it is difficult to compare these results with previous studies.Callaway  reported the contents of mineral elements of the ‘Finola’ variety, which was not analysed in this study, and Mihoc et al. studied five different Romanian varieties that were not analysed in this work either.The sodium content reported by Callaway  was slightly higher, 12 mg/100 g, while all the varieties analysed in this work had sodium content lower than 5 mg/100 g , but its content was much lower than the other macroelements in both cases.That study also reported higher potassium content , closer to hulled hemp seeds than to whole seeds.Mihoc et al. obtained a wide range for this mineral element, from 569.3 to 1889.7 mg/100 g, on average.Two of those varieties had potassiumcontents within the range of this study , but the other three had much higher content.Calcium values reported by Mihoc et al. were close to those of this work , except one of the varieties, which had a content three times higher than the maximum value.The magnesium content range reported by Mihoc et al. included all the values obtained in this work, and Callaway  indicated a higher value, 483 mg/100 g, but close to the maximum obtained in this work.According to Callaway , phosphorus was the most abundant mineral element, but the value was higher, 1160 mg/100 g, closer to phosphorus content in hulled hemp seeds, which were higher than 1000 mg/100 g in every sample.Iron content reported by Callaway  was slightly higher than those of this work, 14 mg/100 g, but the values reported by Mihoc et al. were higher than 160 mg/100 g, 20 times the average value in whole hemp seeds.Manganese, copper, and zinc content data were consistent to those reported by Callaway  and Mihoc et al..

The only literature source of mineral element content data in hulled hemp seeds is the FoodData Central.Sodium, magnesium, calcium, iron, manganese, copper, and zinc values included in the database were close to those of this work, while potassium and phosphorus values, 1200 and 1650 mg/100 g, respectively, were higher than the maximum values obtained in this work.Considering the nutrient reference values  of mineral elements established by the European Union , Fig.1a represents the percentage that 100 g of whole and hulled hemp seeds contribute to those NRVs, while Fig.1b represents the contribution percentages of 30 g, which is the serving size.As it can be seen in Fig.1a, and according to European Union regulation on nutritional claims made in foods, both whole and hulled hemp seeds could be considered high in magnesium, phosphorus, manganese, copper, and zinc because their contributions were higher than 30% of NRVs.The contribution of whole hemp seeds to potassium NRV was slightly lower than 30%, so they could be considered as a source of potassium , while hulled hemp seeds could be considered, high in potassium.Whole, but not hulled hemp seeds, could be considered a source of calcium.