Search Results (11)

In order to improve the durability of loess-based composite coal gangue porous planting concrete (LCPC), the effects of fly ash and slag powder content on the durability and microstructure of LCPC were studied. In this paper, fly ash and slag powder were mixed into LCPC, and freeze-thaw cycle and dry-wet cycle tests were carried out. The compressive strength, dynamic elastic modulus, and mass change were used as evaluation indices to determine the optimal mix ratio for LCPC durability. Scanning electron microscopy (SEM) was performed, and the experimental design was carried out with the water–cement ratio, fly ash, and slag powder content as variables. The microstructure characteristics of LCPC were analyzed. The results show that the maximum number of freeze-thaw cycles can reach 35 times and the maximum number of dry-wet cycles can reach 50 when 5% fly ash and 20% slag powder are used. With an increase in the water-cement ratio, the skeleton of the loess gradually became complete, and its structure became more compact. In the micro-morphology diagram, the mixed fly ash and slag powder particles are not obvious, but with an increase in dosage, the size of the cracks and pores gradually decreases. The incorporation of fly ash and slag powder can play a positive role in the durability of LCPC and improvement of its microstructure. The results of this study are crucial for improving the application performance of ecological restoration, soil improvement, and long-term stability of structures, and can provide a scientific basis for the sustainable development of environmentally friendly building materials. Full article

Vegetation concrete is one of the most widely used substrates in ecological slope protection, but its practical application often limits the growth and nutrient uptake of plant roots due to consolidation problems, which affects the effectiveness of slope protection. This paper proposed the use of a plant protein foaming agent as a porous modifier to create a porous, lightweight treatment for vegetation concrete. Physical performance tests, direct shear tests, plant growth tests, and scanning electron microscopy experiments were conducted to compare and analyze the physical, mechanical, microscopic characteristics, and phyto-capabilities of differently treated vegetation concrete. The results showed that the higher the foam content, the more significant the porous and lightweight properties of the vegetation concrete. When the foam volume was 50%, the porosity increased by 106.05% compared to the untreated sample, while the volume weight decreased by 20.53%. The shear strength, cohesion, and internal friction angle of vegetation concrete all showed a decreasing trend with increasing foaming agent content. Festuca arundinacea grew best under the 30% foaming agent treatment, with germinative energy, germinative percentage, plant height, root length, and underground biomass increasing by 6.31%, 13.22%, 8.57%, 18.71%, and 34.62%, respectively, compared to the untreated sample. The scanning electron microscope observation showed that the pore structure of vegetation concrete was optimized after foam incorporation. Adding plant protein foaming agents to modify the pore structure of vegetation concrete is appropriate, with an optimal foam volume ratio of 20–30%. This study provides new insights and references for slope ecological restoration engineering. Full article

The objective of this study is to formulate vegetated light porous concrete (VLPC) through the utilization of various cementing materials, the design of porosity, and the incorporation of mineral additives. Subsequently, the study aims to assess and analyze key properties, including the bulk density, permeability coefficient, mechanical characteristics, and alkalinity. The findings indicate a linear decrease in the volume weight of VLPC as the designed porosity increases. While higher design porosity elevates the permeability coefficient, the measured effective porosity closely aligns with the design values. The examined VLPC exhibits a peak compressive strength of 17.7 MPa and a maximum bending strength of 2.1 MPa after 28 days. Notably, an escalation in porosity corresponds to a decrease in both the compressive and the bending strength of VLPC. Introducing mineral additives, particularly silicon powder, is shown to be effective in enhancing the strength of VLPC. Furthermore, substituting slag sulfonate cement for ordinary cement significantly diminishes the alkalinity of VLPC, resulting in a pH below 8.5 at 28 days. Mineral additives also contribute to a reduction in the pH of concrete. Among them, silica fume, fly ash, fly ash + slag powder, and slag powder exhibit a progressively enhanced alkaline reduction effect. Full article

Vegetation porous concrete is a novel material that integrates concrete technology with plant growth, offering excellent engineering applicability and environmental friendliness. This material is mainly utilized in eco-engineering projects such as riverbank protection, architectural greening, and slope protection along roads. This paper systematically reviews the current research progress of vegetation porous concrete by collecting and analyzing the relevant literature from both domestic and international sources. It covers several aspects including the material components of vegetation porous concrete, such as aggregates, cementitious materials, chemical admixtures, and plant species, as well as aspects like mix design, workability, porosity, pH value, mechanical strength, and vegetative performance. Furthermore, the application of vegetation porous concrete in riverbank protection, slope protection along highways, and urban architecture is discussed, along with a prospective outlook on future research directions for vegetation porous concrete. Full article

The ongoing climate change is manifesting itself through the increasing expansion of Urban Heat Island (UHI) effects. This paper evaluates the microclimate benefits due to cool road pavements, greenery, and photovoltaic canopies in a parking lot in Fondi (Italy), identifying the best strategy to counteract the negative effects of UHIs. The ENVI-met software allowed a microclimatic analysis of the examined area in July 2022 through the comparison of the thermal performances between the current asphalt pavement and ten alternative scenarios. The proposed layouts were investigated in terms of air temperature (AT), surface temperature (ST), mean radiant temperature (MRT), and predicted mean vote (PMV). The results showed that the existing asphalt pavement is the worst one, while the cool pavement integrated with vegetation provides appreciable benefits. Compared to the current layout, a new scenario characterized by light porous concrete for carriageable pavements and sidewalks, concrete grass grid pavers for parking stalls, a 2-m-high border hedge, and 15-m-high trees implies reductions of AT above 3 °C, ST above 30 °C, MRT above 20 °C, and a maximum PMV value equal to 2.2. Full article

Living walls are becoming a widely used water-sensitive urban design technology that can deliver various economic, social and environmental benefits. One such benefit is to cool the surrounding environment through the process of evapotranspiration. This study measured the evapotranspiration from an instrumented prototype-scale living wall and calculated the resulting evaporative cooling effect. The range of the measured evapotranspiration rates from the living wall was from 41 to 90 mL/mm per plant pot. This equated to latent heat of vaporisation values from 171 to 383 MJ/month/m². This was then compared with the performance of a non-vegetated water-sensitive urban design technology, namely, a porous concrete pavement. For a typical summer month in a warm temperate climate, it was found that a porous concrete pavement system only had between 4 and 15% of the cooling effect of an equivalent living wall. Full article

The feasibility of substitute building materials (SBMs) in engineering applications was investigated within the project. A geogrid-reinforced soil structure (GRSS) was built using SBM as the fill material as well as vegetated soil for facing and on top of the construction. Four different SBMs were used as fill material, namely blast furnace slag (BFS), electric furnace slag (EFS), track ballast (TB), and recycled concrete (RC). For the vegetated soil facing, a mixture of either recycled brick (RB) material or crushed lightweight concrete (LC) mixed with organic soil was used. The soil mechanical and chemical parameters for all materials were determined and assessed. In the next step, a GRSS was built as a pilot application consisting of three geogrid layers with a total height of 1.5 m and a slope angle of 60°. The results of the soil mechanical tests indicate that the used fill materials are similar or even better than primary materials, such as gravel. The results of the chemical tests show that some materials are qualified to be used in engineering constructions without or with minor restrictions. Other materials need a special sealing layer to prevent the material from leakage. The vegetation on the mixed SBM material grew successfully. Several ruderal and pioneer plants could be found even in the first year of the construction. The porous material (RB and LC) provide additional water storage capacity for plants especially during summer and/or heat periods. With regard to the results of the chemical analyses of the greening layers, they are usable under restricted conditions. Here special treatment is necessary. Finally, it can be stated that SBMs are feasible in GRSS, particularly as fill material but also as a mixture for the greenable soil. Full article

To improve aquatic environmental quality and maintain channel stability against soil erosion, ecological bank slope revetments for surface water bodies were developed using a combination of prefabricated porous concrete spheres and vegetation methods, and a model set-up consisting of two equal-sized ditches with different types of bank slope revetments was constructed to evaluate the purification effects of ecological and hard revetments on water quality. The slope of one ditch was embanked with ecological revetments as an experimental treatment, while the other was embanked with hard revetments as a control. Pollutant removal from the ecological bank revetment ditch was significantly better in terms of the overall removal efficiencies of the chemical oxygen demand of manganese (COD_Mn), ammonia, total nitrogen (TN), and total phosphorus (TP), with two- to four-fold greater removal compared with that from hard slope revetments under the same operational conditions. Nutrient pollutants, including ammonia, TN, and TP had higher removal efficiencies than that for COD_Mn in both experimental ditches. The dependence of the first-order rate constant (k₂₀) and temperature coefficient () obtained from the Arrhenius equation indicated that the removal efficiencies for ammonia, TN, and TP were higher with greater rate constants (k₂₀) in the experimental ditch. In the ecological revetment ditch, the k₂₀ values for COD_Mn, ammonia, TN, and TP were 0.054, 0.378, 0.222, and 0.266 respectively, around three-fold the values observed in the hard revetment ditch, but there was no obvious difference in values between the two ditches. The k₂₀ values of TN and TP in both ditches showed significant positive correlations with seasonal shifts, as the removal of nutrient pollutants is highly sensitive to water temperatures. Full article

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. Full article

The purpose of this study is to investigate porous vegetation concrete formed using the industrial by-products blast furnace slag powder and blast furnace slag aggregates. We investigated the void ratio, compressive strength, freeze–thaw resistance, plant growth and water purification properties using concretes containing these by-products, natural jute fiber and latex. The target performance was a compressive strength of ≥12 MPa, a void ratio of ≥25% and a residual compressive strength of ≥80% following 100 freeze–thaw cycles. Using these target performance metrics and test results for plant growth and water purification, an optimal mixing ratio was identified. The study characterized the physical and mechanical properties of the optimal mix, and found that the compressive strength decreased compared with the default mix, but that the void ratio and the freeze–thaw resistance increased. When latex was used, the compressive strength, void ratio and freeze–thaw resistance all improved, satisfying the target performance metrics. Vegetation growth tests showed that plant growth was more active when the blast furnace slag aggregate was used. Furthermore, the use of latex was also found to promote vegetation growth, which is attributed to the latex forming a film coating that suppresses leaching of toxic components from the cement. Water purification tests showed no so significant differences between different mixing ratios; however, a comparison of mixes with and without vegetation indicated improved water purification in terms of the total phosphorus content when vegetation had been allowed to grow. Full article

The purpose of this study was to evaluate the performance of porous vegetation concrete block made from blast furnace slag cement containing industrial by-products such as blast furnace slag aggregate and powder. The blocks were tested for void ratio, compressive strength and freeze-thaw resistance to determine the optimal mixing ratio for the porous vegetation block. An economic analysis of the mixing ratio showed that the economic efficiency increased when blast furnace slag aggregate and cement were used. Porous vegetation concrete blocks for river applications were designed and produced. Hydraulic safety, heavy metal elution and vegetation tests were completed after the blocks were applied in the field. The measured tractive force ranged between 7.0 kg/m² for fascine revetment (vegetation revetment) and 16.0 kg/m² for stone pitching (hard revetment), which ensured sufficient hydraulic stability in the field. Plant growth was measured after the porous vegetation concrete block was placed in the field. Seeds began to sprout one week after seeding; after six weeks, the plant length exceeded 300 mm. The average coverage ratio reached as high as 90% after six weeks of vegetation. These results clearly indicated that the porous vegetation concrete block was suitable for environmental restoration projects. Full article