Vegetation Concrete Research Articles

Ecological Protection Technology of Spraying Vegetation Concrete on Carbonaceous Rock Slope Experimental Research and Application

To solve the environmental protection issue of carbonaceous rock slope, the failure mechanism of carbonaceous rock slope and the protection mechanism of vegetation concrete are analyzed based on the engineering characteristics of carbonaceous rock and vegetation concrete. Therefore, the field test of vegetation concrete was carried out to obtain the optimal dosage of vegetation concrete greening additive. The application of environmental protection technology of vegetation concrete on carbonaceous rock slope is applied in slope engineering of Hebai highway, and the change law of soil fertility was analyzed to verify the effect of ecological protection. The results show that the protection mechanism of vegetation concrete slope protection technology is mainly categorized into two groups, namely, the surface sealing effect of vegetation concrete substrate in the early stage and the plant ecological protection effect in the later stage. The experiment results show that the optimum dosage of green additive for vegetation concrete is ranging from 30 kg/m3 to 40 kg/m3. According to the field application, within one year after the construction of vegetation concrete, the contents of available phosphorus, potassium, and organic matter increased by 70.2%, 24.9%, and 76.8%, respectively. Moreover, the content of alkali hydrolyzed nitrogen decreased by 44.8% and bulk density by 17.4%; the content of total phosphorus changed little. After 60 days of construction, the vegetation coverage rate of the slope can reach more than 95% and there is no obvious soil erosion phenomenon after three times of heavy rainfall.

Vapothermal curing of hemp shives: Influence on some chemical and physical properties

In a perspective of a sustainable development, a new generation of construction materials based on renewable plant resources has emerged to face environmental issues. However, the formulation of structural vegetal concretes (based on plant aggregates, a mineral binder and water) requires to enhance the compatibility of plant aggregates and binder.This paper presents an experimental study that evaluates the influence of vapothermal treatment, a promising method of cure under saturated water vapour pressure, on chemical composition and physical properties (loss of mass, absorption, and specific gravity) of hemp shives, entering in the composition of vegetal concrete. Indeed, developing bio-based concrete by vapothermal curing requires identifying the appropriate curing conditions both from the point of view of the hemp aggregates and the binder. In particular, these curing conditions must respect a compromise between the preservation of the physical and chemical properties of hemp shives and an efficient curing of the binder.Several levels of curing temperatures were defined between 150 and 230 °C (carbonization) and results of Treated Hemp Shives (THS) were compared with those of Raw Hemp Shives (RHS). The experimental results showed physical modifications explained by chemical transformations that affects the hemicellulose, cellulose and lignin composition of TSH and modifies the structure of hemp shives. The effect of vapothermal curing on hemp shives was determined through X-Ray Diffraction XRD and thermogravimetry TG. The loss of mass of THS increases as the curing temperature increases and specific gravity decreases. As for water absorption, which relates to the hydrophilic character of the treated hemp shives, it decreases slightly. This experimental study made it possible to assess the interest of a vapothermal curing in a prospect of using hemp shives in binder interaction in order to perform structural vegetal concrete.

An investigation into the long-term carbonation of vegetal concretes containing a viscosity modifying agent

In modern times issues such as sustainability and carbon footprint have become subjects of significant interest on a global scale. A leading industry in greenhouse emissions is the construction industry, and the industry’s carbon footprint needs to be reduced in order to meet emissions targets. Hemp concrete and rapeseed concrete are two alternative sustainable building materials that can help the construction sector improve and meet those targets. Because of their relatively recent introduction, limited studies are available on the durability of these materials. This paper investigates the effect of long-term accelerated carbonation on hemp and rapeseed concretes manufactured with a natural cement and, in some cases, a polyacrylic acid viscosity modifying agent (VMA). Natural carbonation in an outdoor environment was also studied. It was found that the mixes carbonated quickly under accelerated conditions, however no impact on mass or specimen dimensions were observed. In the case of the VMA mixes, it was found that the compressive strength of the samples was improved compared to the equivalently aged control samples. However, it was found that compressive strength was actually inhibited in the untreated mixes when compared with the control samples.

Resource Allocation Strategy and Soil Driving Factors of Vegetation Concrete Restoration System Under Co-Operating Environment

Resource Allocation Strategy and Soil Driving Factors of Vegetation Concrete Restoration System Under Co-Operating Environment

Seismic Performance of Substrate for Vegetation Concrete from Large-Scale Shaking Table Test

The substrate for vegetation concrete is a new type of plant substrate used for slope protection. While it has demonstrated good performance in slope protection and a greening effect, the sustainability of ecological restoration projects is difficult and there are significant construction risks in areas with frequent earthquakes. In this study, a new type of substrate for vegetation concrete was developed for areas with frequent earthquakes, and a shaking table test was performed to evaluate the seismic performance. The test results indicated that the proposed substrate of the vegetation concrete displayed good stability under seismic excitation at earthquake intensities of V, VI, VII, and VIII. A comparison of several different reinforcement methods under seismic conditions indicated that wavy laying of a flexible net was the best reinforcement method. Through observation of the displacement time history curve and macroscopic phenomenon, the failure process of the substrate layer was obtained and consisted of the following three stages: cracking between substrate layer and bedrock, internal cracking of the substrate layer, and vibration crushing. Ultimately, the research results have significant reference value for ecological restoration projects using substrates for vegetation concrete in areas with frequent earthquakes.

Effects of two types of activated carbon on the properties of vegetation concrete and Cynodon dactylon growth

Vegetation concrete is one of the most widely used substrates for slope ecological protection in China. However, there are still some imperfections that are disadvantageous for plant growth, such as high density, low porosity, insufficient nutrient retention ability and so on. In this paper, the effect of wood activated carbon and mineral activated carbon on the physicochemical properties of vegetation concrete is studied. The experimental results show that the activated carbon proportion in vegetation concrete is positively related to the porosity, permeability coefficient, water holding capacity, and nutrient content and retention ability, while it is negatively related to the dry density, water retention ability, cohesive force and internal friction angle. However, it should be noticed that when the proportion exceeds 2%, the average height, aboveground biomass and underground biomass of Cynodon dactylon decrease with increasing proportion of activated carbon. The effect of wood activated carbon is generally more remarkable than that of mineral activated carbon. In addition, according to the research results, the effect of activated carbon on vegetation concrete can last for at least half a year, although it does slowly deteriorate with increasing time. By comprehensive consideration of the current industry standard, previous research results and economical reasoning, the recommended type of activated carbon is wood, with a corresponding suitable proportion ranging between 1 and 2%.

Study on Vegetation Concrete Technology for Slope Protection and Greening Engineering

Study on Vegetation Concrete Technology for Slope Protection and Greening Engineering

RETRACTED: The evolution of structure properties of vegetation concrete under freeze–thaw cycles

Vegetation concrete is a typical artificial composite soil commonly used for ecological restoration on slopes. The strength and stability of vegetation concrete would be reduced when it is used in areas where freeze–thaw cycles occur frequently. For exploring the changes of structural properties of vegetation concrete under freeze–thaw cycles, an indoor simulation experiment of vegetation concrete samples containing 25 and 30% water content was carried out, so as to test the changes of specimen surface, volume, ultrasonic wave velocity, shearing strength, and microscopic structure. The microstructural parameters were analyzed quantitatively with Image-Pro Plus software. The experimental results indicated that as cycles of freeze–thaw grow, the macroscopic changes of samples included steadily rising surface crack rate, increasing first and then decreasing volume, greatly reducing ultrasonic wave velocity and gradually decreasing shear strength. The inner structure of samples slowly deteriorated from overall dense to dispersed with decreasing cement hydration crystals, pores resulting from dispersion and destruction of bulky grains, higher surface porosity, and smoother particles in microscopic aspect. When compared with samples containing 25% water content, the microstructure of the 30% water content sample was more affected by the freeze–thaw cycle, and its structural weakening effect was more obvious. Reduced cement hydration crystals, lower inter-particle bonding force, and increase in the number of large pores were the main causes of degradation of vegetation concrete structure. Electrical engineering students can refer to the analysis methods in this paper to evaluate the structural performance of any electrical engineering material.

Multiproperty characterization of cleaner and energy-efficient vegetal concrete based on one-part geopolymer binder

The growing concerns of increase in carbon emission have obliged engineers and scientists to avert global warming and catastrophic changes in climate, which has brought up the necessity of utilizing waste materials from different industries and producing vegetal concrete using biomass. In this research, a new type of energy-efficient and sustainable concrete based on industrial waste materials and vegetal aggregate was produced for the hygrothermal and low load-bearing application. The performance of vegetal concrete was evaluated by studying the mechanical, microstructural, thermal, heat loss and hygroscopic properties. Compressive and flexural strength for all vegetal concrete mixtures varied from 1.13 to 5.72 MPa and 1.65–3.27 MPa respectively. Results of mechanical properties were in consistence with the microstructure analysis of vegetal concretes. Coefficients of thermal conductivity, volumetric specific heat capacity, and thermal diffusivity were in the range of 0.114–0.192 Wm−1K−1, 0.81–1.321 MJm−3K−1, and 0.109–0.145 mm2 s-1 respectively. Coefficients of thermal properties of vegetal concrete increased with the rise of the temperature from 20°C to 50°C. Heat loss analysis showed that use of vegetal concrete as an insulation material can reduce the energy losses through the wall by 46–58% as compared to reference wall. Vegetal concrete mixtures containing red mud exhibited higher capillary and water absorption as compared to other mixtures. Moreover, all concrete mixtures were classified as good to excellent moisture buffer materials. Finally, vegetal concrete mixtures were classified into class-II and class-III according to functional classification of lightweight concrete.

Impact of Bio-Aggregates Properties on the Chemical Interactions with Mineral Binder, Application to Vegetal Concrete

Plant concretes were developed and are currently used as filling material in a timber frame. Their properties are strongly related to the bio-aggregates characteristics. In addition, since hemp shiv, the reference bio-based aggregate, has a limited availability, it is necessary to consider alternative bio-aggregates largely and locally available. Thus, this paper focused on identifying and understanding mechanisms of interaction between different bio-aggregates and mineral binders. To address this issue, the first objective was to determine the properties of five hemp shives and two alternative bioaggregates for vegetal lightweight concrete: corn and sunflower bark particles. The study of the chemical interactions between bio-aggregates and a pozzolanic binder was conducted on model pastes mixed with filtered solutions containing bio-aggregates extractives. The mechanical properties of the paste, as well as their hydration and their mineralogical evolution were studied. In the last part, the mechanical behavior of vegetal concretes was assessed. The results highlight a strong relation between the mechanical behavior of pastes and concretes and the extractive content of the different tested bio-aggregates. Finally, pastes appeared as a relatively good model to predict the behavior of concretes by following their early age performances: setting delay and 3-day mechanical strength.

A Review of Research Progress of Vegetation Concrete on Coastal Highway Slope

Li, C.; Zhao S.-Y.; Zhou H.-Q., Liu C., and Zhang, Y.-T., 2019. A review of research progress of vegetation concrete on coastal highway slope. In: Gong, D.; Zhu, H., and Liu, R. (eds.), Selected Topics in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 94, pp. 367–371. Coconut Creek (Florida), ISSN 0749-0208.As a main road connecting the city and a landscape road, the coastal road is particularly important to the greening of the exposed slope in order to avoid the formation of a large number of exposed rock slopes in the construction process and affect the landscape. In view of the difficulty in greening the rock slope, the development of new materials such as vegetation concrete (VC) can effectively control the greening problem of rock slope. For this, this paper briefly introduces the development process of slope greening, discusses the research progress of VC from the aspects of substrate ratio, mechanical property, root-soil combination effect and fertility level, and then studies the problems existing on the current research. Finally, it proposes several prospects for the greening construction of rock slope.

A review of the properties of hemp concrete for green building applications

Abstract The growing concerns surrounding the rising carbon emissions have impelled the leaders around the world to make efforts to prevent catastrophic manifestations of climate change and global warming. This has led to the resurrection of vegetal concrete building materials using biomass, which have the added benefits of carbon sequestration apart from low embodied energy and renewability. Vegetal concretes are made up of an organic or inorganic binder, and biomass originating from agro-forestry industries such as rice husk, straw bale, hemp, kenaf, cork, and so on. Hemp concrete, a variety of vegetal concrete has been widely researched and is arguably one of the most researched building materials in current times. This paper presents a review of the state-of-the-art of hemp concrete research, with a view to identifying research gaps that shall guide future research for its implementation in the fast-growing green buildings industry. The reviewed aspects of hemp concrete include properties of hemp relevant to construction, binder characteristics, mechanical properties, durability, hygric and thermal properties, environmental credentials, manufacturing processes, and current applications. Several research gaps with regards to the hydraulicity of the binder, strength and durability, and fire resistance of hemp concrete were identified. It was also established that hemp concrete has very low embodied carbon and embodied energy, making it ideal for green building applications. The paper ends with a discussion outlining the need and direction for future research on improving the manufacturing processes and mechanical performance of hemp concrete for wider adoption by the construction industry.

Influence of types of binder and plant aggregates on hygrothermal and mechanical properties of vegetal concretes

Bio-aggregate based building materials offer promising perspectives thanks to their low environmental impact and interesting hygrothermal behaviour. In this paper, different formulations of bio-aggregate concrete are proposed and analysed. We focus on two types of locally available bio-aggregates, namely maize and sunflower bark chips, and two types of binder matrices, based on respectively metakaolin and lime. The study specifically focuses on the pore structure of the composite material, as this quantity has a decisive impact on the insulating properties (thermal conductivity), the hygric behaviour (sorption isotherms, water vapour permeability and moisture buffer value) as well as on the mechanical performance (compressive strength). The results underline the impact of the constituents’ porosity on the complex porous structure of the bio-concrete and the influence of porosity on its performance. The findings demonstrate that metakaolin and sunflower are high-potential raw materials for the design of a bio-aggregate based concrete.

Experimental Study on the Vegetation Growing Recycled Concrete and Synergistic Effect with Plant Roots.

Vegetation growing recycled concrete (VGRC) is a relatively new building material that has both biocompatibility and engineering function. The basic performance of VGRC was investigated by experimental analysis, and the hydration products and pore structure of different VGRC mix proportions were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and industrial computed tomography (CT). The results show that ultrafine slag can reduce Ca(OH)2 content in cementing material and has a filling effect on micropores. VGRC has the best performance; the internal pore distribution is uniform when porosity is 20–25%, and the ultrafine slag content is 40%. The compressive strength of VGRC is greatly damaged by the quick-freezing method, while the degree of damage from natural freeze–thaw cycles is relatively small. Soaking in acid solution can effectively reduce the internal pore alkalinity of VGRC. Most plants can grow normally in vegetation concrete, and plant roots can penetrate 6-cm thick concrete blocks after being planted for 60 days. The compressive strength of VGRC decreased after turf planting of 30 days and then increased slowly. The permeability coefficient of VGRC increases with the increase in porosity and aggregate size and decreases after planting and covering. The frost resistance of VGRC is enhanced, and the influence of aggregate size and porosity is small after turf planting.

Experimental study on the vegetation characteristics of biochar-modified vegetation concrete

Vegetation concrete is an effective material to beautify the landscape, reduce pollution and protect the environment. To further improve the plant compatibility of vegetation concrete, this paper recommends an improved method of adding biochar particles to vegetation concrete. In this research, different masses of biochar were mixed into concrete to study the trend in porosity, permeability and plant compatibility. According to the growth status of three types of common grass species, ryegrass was selected as the best grass species in this study. As the content of biochar increased, the porosity and permeability coefficient of vegetation concrete continued to decrease, while the effect of biochar on plant growth promotion at first showed an increase to the maximum and then a gradual decrease. When the biochar content was 5 kg/m3, ryegrass showed the best growth. Compared with the experimental group of vegetation concrete without biochar, the plant height, root length and germination rate increased by 22.2%, 21.1% and 12%, respectively, on day 25, and the compressive strength also increased slightly. Therefore, adding a suitable amount of biochar can improve the characteristics of vegetation concrete. Furthermore, the optimum mix proportion of biochar-modified vegetation concrete was recommended.

Impact of bio-aggregates properties on the chemical interactions with mineral binder, application to vegetal concrete

Impact of bio-aggregates properties on the chemical interactions with mineral binder, application to vegetal concrete

Aging of hemp shiv used for concrete

Functional properties of vegetal concretes, such as hygrothermal and acoustical properties, are brought by the microstructure of the vegetal particles. However, data are necessary to develop biobased insulation materials by providing results on their long-term behaviour, and only few studies focus on this topic. A first step is to characterise the behaviour of vegetal aggregates in bulk.In this study, hemp shiv is stored for two years in three different conditions: a static environment used as reference, accelerated aging conditions based on humidification and drying cycles, and an exterior aging. The potential evolution of functional properties of particles is monitored with time and depending on the aging conditions. These evolutions are understood thanks to a study at a microscopic scale, where the microstructure of the particles is investigated.This study shows that no variation is observed for the reference conditions, whereas four phenomena linked to aging can be identified for accelerated and exterior aging conditions: a mass loss, volume variations of the particles and an opening of the aggregates porosity for both storing conditions. The last one, only observed for exterior aging, is a modification of the pore size distributions.

마그네시아 인산염 복합체의 강도 및 pH에 대한 인산염 종류의 영향

본 연구는 식생 콘크리트 개발에 대한 기초적인 연구로 낮은 pH특성을 갖는 마그네시아-인산염 복합체(MPC)의 압축강도 및 pH 특성을 평가하였다. 주요 변수는 인산염 종류이며, 8종의 인산염(암모늄계, 나트륨계, 칼륨계, 칼슘계)을 사용하여 모르타르 및 페이스트를 제작하였다. 실험결과, 제 2 인산나트륨, 제 2 인산칼륨 및 제 2 인산칼슘의 경우 MPC 모르타르의 압축강도 발현에 대한 영향은 없었다. 제 1 인산암모늄, 제 1 인산칼륨을 적용한 MPC모르타르의 경우 34MPa 이상의 압축강도가 발현되었으며, pH는 9.8이었다. 따라서 식생용 콘크리트의 결합재로 제 1 인산암모늄 및 제 1 인산칼륨인산염이 적용된 MPC가 가장 효과적일 것으로 기대된다. As an elementary investigation to develop vegetation concrete with a relatively low pH value, magnesia-phosphate composites (MPC) were examined according to the phosphate types including Monoammonium, Monosodium, Monopotassium, Monocalcium, Diammonium, Disodium, Dipotassium, and Diacalcium phosphates. All of the MPC binders, the ratio of magnesia to phosphate was fixed to be 7:3. MPC mortars activated with Disodium, Dipotassium, and Diacalcium phosphates showed no compressive strength gain, even at age of 28 days. Meanwhile, MPC mortars with Monoammonium and Monosodium phosphates developed 28-day compressive strength of more than 34MPa, and showed a relatively low pH value below 9.8. Hence, Monoammonium and Monosodium phosphates have potentials as an activator for producing MPC-based vegetation concrete.

Carbon Dioxide Emission Evaluation of Porous Vegetation Concrete Blocks for Ecological Restoration Projects

The purpose of this study is to determine the mix proportions that can minimize CO2 emissions while satisfying the target performance of porous vegetation concrete. The target performance of porous vegetation concrete was selected as compressive strength (>15 MPa) and void ratio (>25%). This study considered the use of reinforcing fiber and styrene butadiene (SB) latex to improve the strength of porous vegetation concrete, as well as the use of blast furnace slag aggregate to improve the CO2 emissions-reducing effect, and analyzed and evaluated the influence of fiber reinforcing, SB latex, and blast furnace slag aggregate on the compressive strength and CO2 emissions of porous vegetation concrete. The CO2 emissions of the raw materials were highest for cement, followed by aggregate, SB latex, and fiber. Blast furnace slag aggregate showed a 30% or more CO2 emissions-reducing effect versus crushed aggregate, and blast furnace slag cement showed a 78% CO2 emissions-reducing effect versus Portland cement. The CO2 emissions analyses for each raw material showed that the CO2 emissions during transportation were highest for the aggregate. Regarding CO2 emissions in each production stage, the materials stage produced the highest CO2 emissions, while the proportion of CO2 emissions in the transportation stage for each raw material, excluding fiber, were below 3% of total emissions. Use of blast furnace slag aggregate in porous vegetation concrete produced CO2 emissions-reducing effects, but decreased its compressive strength. Use of latex in porous vegetation concrete improved its compressive strength, but also increased CO2 emissions. Thus, it is appropriate to use latex in porous vegetation concrete to improve its strength and void ratio, and to use a blast furnace slag aggregate replacement ratio of 40% or less.

Influence of accelerated aging on the properties of hemp concretes

The use of vegetal concretes, such as hemp concrete, is growing for building insulation. They are constituted by vegetal aggregates embedded in a mineral binder. Hemp concretes are multifunctional materials: they have interesting thermal and acoustical performances and their hygrothermal behavior enables a natural moisture regulation. Currently, their use is limited by their lack of guarantees in terms of durability. This paper focuses on the influence of 75days of wetting and drying cycles on hemp concrete properties. It is shown that this aging induces modifications of the porosity of the materials and of their skeleton density. However, these evolutions of microstructure are not sufficient to lead to modifications of thermal and acoustical performances. This work has also shown that mold growth occurs when the relative humidity is high (98% RH) and when the pH of the binder has decreased due to its carbonation reaction.