Lightweight Expanded Clay Aggregate Research Articles

Biogeochemical Permeable Barrier Based on Zeolite and Expanded Clay for Immobilization of Metals in Groundwater

Groundwater samples contaminated with potentially toxic elements (PTE), including metals and nitrate ions, were collected at a depth of 8–10 m from the Siberian Chemical Plant multicomponent waste storage. The possibility of developing a permeable biogeochemical barrier with zeolite and lightweight expanded clay aggregate (LECA) was investigated. The mass fraction and properties of several metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg and Pb) were determined to investigate their fixation on the chosen materials at the given experimental conditions. It was established that metals in sulfide or phosphate forms can be effectively immobilized via biomineralization on LECA, whereas metals from the non-chalcogen group are primarily retained in the form of phosphates. The formation of biogenic deposits of iron sulfide, which serve as a sorption–precipitation phase during the immobilization of the majority of metals, is an important aspect of the LECA loading process. The use of LECA and zeolite in the form of a two-component barrier is feasible based on the data obtained. It is assumed that metal immobilization processes occur due to sorption mechanisms in the zone of zeolite loading. Microbial nitrate removal and the formation of iron sulfide phases under reducing conditions, which form a geochemical barrier for metals, are expected in the LECA zone.

The effect of biochar and acid activated biochar on ammonia emissions during manure storage

Animal manure contains valuable plant nutrients which need to be stored until field application. A significant proportion of slurry nitrogen is volatilized in the form of ammonia (NH3) during storage. This impacts human health, biodiversity, air and water quality and thus urgent action is needed to reduce NH3 emissions. In this experiment, we evaluated the NH3 emission mitigation potential of biochars derived from miscanthus (MB) and solid separated anaerobic digestate (DB), and orthophosphoric acid activated MB (AMB) and DB (ADB) as well as lightweight expanded clay aggregate (LECA) during four months of liquid manure storage. A slurry without amendment was included as a control (Ctrl). Acid activated and non-activated biochars were applied on top of the slurry maintaining a 7 mm thick surface layer, while LECA was applied in a 2 cm thick layer. NH3 emissions were measured by photoacoustic analyzer. In comparison to Ctrl, acid activated biochar decreased (p < 0.05) NH3 emissions during the slurry storage. Activated biochar reduced the emissions by 37–51% within the first month of slurry storage and achieved a 25–28% emissions reduction efficiency throughout the four month period due to the reduction in emission mitigation efficiency as the storage period progressed. LECA reduced NH3 emissions by 21% during storage. Losses of NH3 as a percentage of total ammoniacal N were 29–31% for activated biochars, 35–39% for non-activated biochars and 33% for LECA. In conclusion, acid activated biochars and LECA could be good floating-covers to mitigate NH3 emissions during manure storage, but activated biochars may have better mitigation potential than LECA.

Water permeability, water retention capacity, and thermal resistance of green roof layers made with recycled and artificial aggregates

Substituting natural aggregates in the green roof substrate and drainage layers with lightweight artificial and recycled coarse materials is an eco-friendly alternative for applying lower load to the rooftops and preserving natural resources. However, a lack of precise understanding of the thermal resistance, water passing ability, and water holding capacity of green roof materials, including recycled and artificial materials, has raised a demand for measuring their Rc-value, water permeability, and water retention capacity as three main indicators for green roof systems. This study comparatively evaluated the thermal resistance, water permeability, and water retention capacity of green roofs with substrate and drainage layers, including coarse recycled and artificial materials. Different kinds of coarse granular aggregates were separately used for the drainage layer, including Natural Coarse Aggregate (NCA), Recycled Coarse Aggregate (RCA), Incinerated Municipal Solid Waste Aggregate (IMSWA), and Lightweight Expanded Clay Aggregate (LECA). The substrate layers were made with coarse recycled materials (SC) and without coarse recycled materials (SP) in wet and dry states. The outcomes revealed the highest thermal resistance and the lowest weight were obtained for 20-cm green roofs with a 15-cm substrate layer and 5-cm drainage layer of LECA. The water permeability of NCA was obtained 1.5 times more than that of LECA, whereas there was no significant difference between the result of the former, RCA, and IMSWA. The water retention capacity of the LECA was two times higher than that of the NCA. SC and SP satisfied the water passing and retention criteria given for green roofs.

The Use of Lightweight Aggregate in Concrete: A Review

One of the artificial lightweight aggregates with a wide range of applications is Lightweight Expanded Clay Aggregate. Clay is utilized in the production of light aggregates. Using leftover clay from significant infrastructure development projects to manufacture lightweight aggregates has a favorable environmental impact. This research examines the expanded clay aggregate production process and the impact of processing parameters on its physical and mechanical qualities. It also looks at secondary components that can be used to improve the qualities of concrete with expanded clay aggregates. The effect of the quantity of expanded clay aggregate on the fresh, hardened, and durability qualities of concrete is also studied. Expanded clay aggregates improve workability, fire resistance, sound insulation, and thermal insulation in concrete. Its inclusion, on the other hand, diminishes concrete's density, strength, elastic modulus, and resistance to freeze-thaw action.

Assessment of subsurface migration and simultaneous removal of Carbendazim in simulated constructed wetland through physical and numerical modeling

Indiscriminate disposal of hazardous waste into land generates harmful effects in the lithosphere. Carbendazim is widely used to prevent fungal diseases in agricultural fields and industries, such as paper, leather, and paint, in an uncontrolled manner and is reported as a possible human carcinogen when consumed. Therefore, it is urgently needed to find effective methods to remove Carbendazim from wastewater. In this investigation, Lightweight Expanded Clay Aggregate (LECA) and silty sand have been explored as alternating bed materials in a Constructed Wetland with Chrysopogon zizanioides for phytoremediation to attenuate Carbendazim from wastewater. The hydraulic conductivity of the soil and LECA were found as 1.63 × 10−7 m/s and 1.12 × 10−3 m/s, respectively. Batch adsorption test data exhibited that Langmuir and Pseudo second-order were the best fitting isotherm and kinetic models in both cases, with Regression Coefficient (R2) values of 0.99 for all also LECA had a high adsorptive capacity for the depletion of Carbendazim. Constructed Wetland study with LECA and phytoremediation using Chrysopogon zizanioides yielded maximum removal efficiency of Carbendazim in the range of 96–99.6 %, which corroborated closely with the results from the HYDRUS model. Results demonstrate the combined efficacious use of LECA and Chrysopogon zizanioides to abate Carbendazim from wastewater, which can be recommended as a cost-effective solution for its field-scale applications.

An experimental study on mechanical and thermal properties of structural lightweight concrete using carbon nanotubes (CNTs) and LECA aggregates after exposure to elevated temperature

• The effects of high temperature on LWC with carbon nanotubes (CNTs) and structural LECA as coarse aggregates are investigated • The addition of CNTs to LWC brings in an improvement of the tensile properties at high temperature • LWC containing CNTs exhibits a lower thermal conductivity, to the advantage of the insulating power of concrete in fire The effects of elevated temperature on lightweight structural concrete (LWC) containing Carbon Nanotubes (CNTs) and structural Lightweight Expanded Clay Aggregates (LECA) as a substitute for coarse aggregates are investigated. Mechanical properties such as compressive, indirect tensile strength (in splitting and bending) of a 7-day and 28-day structural LWC (with and without CNTs) have been evaluated under different temperature ranges from ambient temperature up to 800 °C. Moreover, in order to capture all aspects, along with characterizing the mechanical response of the concrete, thermal conductivity has also been measured to understand the thermal behavior of structural lightweight concrete. Hereafter, to bring together different results so that the similarities and differences can be seen, each achieved result from present research has been compared to that of literature. Results indicate that all mechanical properties of the structural LWC containing CNTs were improved at different temperatures compared to those without CNTs. The reasons for the improvement were interpreted by Scanning Electron Microscope (SEM). Moreover, thermal test results demonstrate a decrease in thermal conductivity to the advantage of possible high-temperature applications.

Mechanical properties of lightweight expanded clay aggregate (LECA) concrete

The construction activities are based on structural concrete, which is one of the most commonly used materials. The fundamental aim of using lightweight concrete (LWC) was to reduce the concrete self-weight of the structure parts. As a result, LWC has been used successfully in a variety of installations for several years. In this paper, the mechanical properties of concrete made with lightweight expanded clay aggregate (LECA) as a full replacement for coarse aggregate are studied. The experimental program shows that LECA with a 32 MPa cube compressive strength and an 1,823 kg×m–3 dry density can be used to make structural light-weight aggregate concrete (SLWC). The results show that the reduction in the strength of lightweight aggregate concrete (LWAC) was found to be higher in the concrete with an estimated compressive strength of 32 MPa due to the lower strength of the LWA (expanded clay). According to the test results, the mechanical properties of LWC were greatly improved by adding silica fume (SF). Furthermore, LECA concrete has a splitting tensile strength that is 47% higher than the ASTM C330/C330M-17A minimum requirement. The LECA concrete has a splitting tensile strength to compressive strength ratio of approximately 13%. Additionally, the results demonstrate a 27% difference in the modulus of elasticity between the calculated and tested values.

Thermo-mechanical efficiency of fibre-reinforced structural lightweight aggregate concrete

The construction industry must consider not only the mechanical performances of structural materials but also their thermal performances for energy-efficient buildings. There exist conflicting thermal and mechanical properties between normal weight concrete (NWC) and lightweight aggregate concrete (LWAC). NWC with high mechanical strength exhibits poor thermal efficiency but LWAC possesses low mechanical strengths but high thermal efficiency. The inclusion of fibres in the mixture of LWAC could provide a solution to its weaknesses in mechanical properties however its thermal performance was not well fully understood. To produce an energy-efficient building material, this study was conducted to determine thermo-mechanical performances of steel (ST) and polypropylene (PP) fibre-reinforced LWACs that meet the structural code requirements with good thermal properties. Lightweight expanded clay aggregate was used to make a structural LWAC and polypropylene and steel fibres were used as the reinforcement. Test results revealed that structural LWAC reinforced ST fibre with 1.0% dosage has the best mechanical and thermo-mechanical efficiency whilst PP fibre with 0.3% dosage has the best thermal performance.The ST fibre has a positive influence on the compressive and tensile strength than PP fibre. In terms of overall thermal performance and cost, LWAC containing 0.3% PP fibre was the most desirable. The PP fibre has a more positive influence on thermal properties than ST fibre. The equations had been proposed with a good correlation of R2 > 0.7979 to predict the thermal properties against density for ST and PP fibres. The new merit Mo equation provides a novel way to measure the thermo-mechanical efficiency of the building materials for the construction industry. ST fibre is better than PP fibre in enhancing the mechanical efficiency but PP fibre is more efficient than ST in enhancing the thermal efficiency of fibre-reinforced LWAC.

Physical profile and chemical composition of a novel fabricated Kaolina as alternative growing media in aquaponics

The physical profile and chemical composition of growing media are vital in evaluating fish waste filtration efficiency and plant growth performance in aquaponics. The present study reported and compared the physical and chemical evaluation of the novel fabricated Kaolina, gravel, and commercially used lightweight expanded clay aggregate (LECA) as growing medias in aquaponics. Field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX) was utilized to analyze the growing media's chemical composition and structural characterization. The resultant effect of these growing medias on water quality and the growth performance of Clarias gariepinus and Lactuca sativa were also reported. Kaolina exhibited an excellent physical profile (42.95 ± 1.39%) in water absorption capacity as compared to LECA (35.90 ± 1.28%) and gravel (1.97 ± 0.25%), showing a significant difference at p < 0.05. The addition of 25% w/w Musa paradisiaca peel in the fabrication of Kaolina gives an added value of 88.0% of K and 100% of P elements, which show a significant difference (p < 0.05) compared to LECA. The results obtained reveal a better daily growth rate (DGR) and relative growth rate (RGR) of L. sativa at 0.57 ± 0.02 cm day−1 and 0.21 ± 0.00 g day−1, respectively. Results indicated that the porous structure of growing media could contribute to the high-water retention capability and slow the water desorption process. Hence, it could increase the ability of the growing media to hold nutrients for plant intake, resulting in higher removal percentage of nutrients in aquaponics system. Kaolina gives the highest nutrient removal percentage of TAN (96.86 ± 1.50%), NO2− (83.56 ± 1.27%), NO3−(77.55 ± 0.48%), and PO43− (79.46 ± 0.42%). The results also shown growing media has considerable impacts on nutrient removal, which contribute to the aquaponic productions.

Photogrammetry-Based Volume Measurement Framework for the Particle Density Estimation of LECA.

This paper presents a photogrammetry-based volume measurement framework for the particle density estimation of Lightweight expanded clay aggregate (LECA). The results are compared with computed tomography (CT) and Archimedes’ method measurements. All of the steps required in order to apply the proposed approach are explained. Next, we discuss how the interpretation of open pores affects the results of volume measurements. We propose to process the shapes obtained from different methods by applying an Ambient Occlusion algorithm with the same threshold, t = 0.175. The difference between the CT and SfM methods is less than 0.006 g/cm3, proving that the photogrammetry-based approach is accurate enough. The Archimedes’ method significantly overestimates the density of the particles. Nevertheless, its accuracy is acceptable for most engineering purposes. Additionally, we evaluate the accuracy of shape reconstruction (in terms of the Hausdorff distance). For 95% of the grain’s surface, the maximum error is between 0.073 mm and 0.129 mm (depending on the grain shape). The presented approach is helpful for measuring the particle density of porous aggregates. The proposed methodology can be utilized in order to estimate intergranular porosity, which is valuable information for the calibration of DEM models.

Influence of Amount of Light Weight Aggregate on Properties of Self Compacting Concrete

Concrete with low density is termed lightweight concrete. The unit weight of such concretes is about two-thirds of normal concrete. Most structural lightweight concretes weigh between 1600 and 1760 kg/m3. Design strengths between 20 to 35 MPa are common. The lightweight nature of these concretes is usually obtained either by using lightweight cellular aggregates. LWC can be produced by using lightweight materials like Lightweight Expanded Clay Aggregate, Pumice stone, expanded shale, Perlite etc. Structural lightweight aggregate can be produced naturally or from environmental waste. use of these aggregates can reduce the density of concrete, the self-weight of the structure and it helps to construct larger precast unit. Lightweight concrete (LWC) is an exceptional solution in terms of decreasing the dead weight of the structure, while self-compacting concrete (SCC) eases the pouring and eliminates construction difficulties. Investigations are also reported the literature on the performance of micro silica in SCC wall panels. The Self-Compacting Concrete made by partially varying coarse aggregate with the lightweight pumice aggregate is described in the paper. This paper presents the fresh and hardened properties of low strength grade and standard grade, self-compacting concrete partially incorporating pumice as coarse aggregate with different replacements. This experimental study also compares the fresh and hardened concrete properties of conventional self-compacting concrete and Light weight self-compacting concrete. The fresh concrete test properties were examined using the slump flow, T500, and J-ring tests. Hardened concrete test properties incorporate 7-, 28- and 56-days compressive strength tests. From the test results it is found that Lightweight self-compacting concrete exhibits better flow property than conventional self-compacting concrete.

Investigation on optimal lightweight expanded clay aggregate concrete at high temperature based on deep neural network

AbstractThis study explores the effects of mixture design parameters on the residual mechanical properties of lightweight expanded clay aggregate (LECA) concrete exposed to elevated temperatures. A total of 30 lightweight concrete mixtures were cast and exposed to three elevated temperatures, namely 250°C, 500°C, and 700°C. The test variables comprised the LECA percentage used as partial volume substitution for natural sand (0%, 25%, 50%, 75%, and 100%), silica fume partial replacement for cement by weight (5%, 7.5%, 10%, 12.5%, and 15%), cement content (300, 400, 500, 600, and 700 kg/m3), and different water‐to‐cement (W/C) ratios (0.25, 0.313, 0.375, 0.438, and 0.5). The compressive and indirect tensile strengths were measured before and after exposure to elevated temperatures. The results indicate that the lightweight concretes incorporating higher contents of cement and silica fume and made with lower W/C ratio exhibited higher initial mechanical properties yet incurred more significant drop in mechanical properties after exposure to 500°C and 750°C.

Impacts of Lightweight Aggregate Interlayers for Air Convection Embankment on Pavement Thermal Profile and Pavement Performance in Alaskan Permafrost Regions

Crushed-rock air convection embankment (ACE) has been used to mitigate pavement distresses caused by climatic extremes in permafrost regions for more than three decades. This study proposes using lightweight aggregates as cost-effective alternative materials to overcome the shortage of desired crushed rocks needed for ACE in interior Alaska. This paper presents an investigation of the performance of six selected pavement structures: an asphalt pavement typical of the northern region of Alaska and five pavements reinforced with different paving interlayers (i.e., silty sand/gravel, crushed rocks, cellular concrete aggregate, foam glass aggregate, and lightweight expanded clay aggregate). Pavement thermal analyses using Temperature Estimate Model for Pavement Structures (TEMPS) program and ANSYS Fluent software were performed to predict heat transfer patterns and thermal performance for each case. Pavement performance analyses using viscoelastic-based FlexPAVE™ and the elastic-based Alaska Flexible Pavement Design (AKFPD) program were conducted to evaluate the long-term performance and structural stability of subgrade soil with different types of interlayers. The results showed that the lightweight aggregate ACEs improved cooling performance more effectively than the crushed-rock ACE. The lightweight aggregate interlayers could maintain desired thermal insulation in summer and enhance the cooling effect in winter. The modeling results identified the high potential of using lightweight aggregates as alternative ACE materials to improve pavement service life and subgrade stability.

Influence of Different Ambient Temperatures on the Thermal Properties of Fiber-Reinforced Structural Lightweight Aggregate Concrete

This study reports the influence of different climatic ambient temperatures on the thermal properties of fiber-reinforced lightweight aggregate concrete (LWAC). Lightweight expanded clay aggregates (LECA) with steel (ST) and polypropylene fibers were used in the mix proportions. The steady-state thermal test was performed on concrete samples at the oven-dry state with the measurement taken at six different climatic ambient temperatures of 0 °C, 10 °C, 20 °C, 30 °C, 40 °C, and 50 °C. The results show a linear dependence of thermal conductivity, specific heat, thermal diffusivity and thermal effusivity of fiber-reinforced LWACs against the different ambient temperatures. These ambient temperature variations are discussed as a function of the thermal properties of fiber-reinforced LWAC. The thermal conductivity and thermal diffusivity decrease linearly between 0 °C and 50 °C, whilst the specific heat and thermal effusivity increase linearly between 0 °C and 50 °C. Equations with strong correlations to predict thermal properties of fiber-reinforced LWAC were proposed based on the results of this study. The significance of this research is to propose the dynamic ambient temperature-dependent thermal properties equations that can be used in the energy analysis of the buildings.

A Study on the Potential Use of Red Clay and Fly Ash in the Production of Lightweight Expanded Clay Aggregates for Concrete

A Study on the Potential Use of Red Clay and Fly Ash in the Production of Lightweight Expanded Clay Aggregates for Concrete

Mechanical Properties of Light Weight Concrete using Lightweight Expanded Clay Aggregate

Abstract: This research investigates the impact of partially substituting coarse aggregate with light weight coarse material (LECA). In numerous aspects, LECA mirrors the properties of coarse aggregate. Because self-weight accounts for a major amount of the total load applied to the structure, LECA is utilized in concrete to lower the need for coarse aggregate and in the design of concrete buildings. This is crucial in circumstances like poor soils and tall constructions. It also offers significant advantages in terms of lowering concrete density, which improves labour efficiency. Lightweight concrete has a lower density than standard concrete and provides better thermal insulation. The main purpose of this study is to examine the weight and strength characteristics of concrete, such as cube compressive strength, split tensile strength cylinders, and flexural strength of light weight concrete versus conventional concrete by substituting LECA for natural aggregates by 25%, 50%, 75%, and 100%, respectively. For far over two millennia, lightweight aggregate has been used successfully. Keywords: Lightweight Expanded Clay Aggregate (LECA), Light-weight concrete, Flyash, Compressive Strength, Density.

Assessment of the contribution of various constructed wetland components for the removal of pharmaceutically active compounds

Constructed wetland (CW) is being used to attenuate pharmaceutically active compounds (PhACs) from wastewater. In this study, the fate of three PhACs – atenolol (ATL), carbamazepine (CBZ), and diclofenac (DCF) was investigated in each component of the CW. The acclimatized microbes showed effective degradation of PhACs at initial concentrations of 100 µg/L under different redox conditions, with degradation rates in the order of ATL > CBZ > DCF. The hydroponics study with Canna indica removed 19.3–31.2 % without substrate materials (initial PhACs:100 µg/L each). The breakthrough and sorption capacity of unplanted CW followed the order: natural zeolite (1.6–2.15 µg/g) < Light-weight expanded clay aggregate (LECA) (5.37–8.27 µg/g) < waste autoclaved aerated concrete (AAC) block (9.27–10.79 µg/g) < wood charcoal (24.1–26.4 µg/g), according to their surface and textural properties. Eventually, four laboratory-scale CW units with enriched microbes, C. indica, and different supporting materials were monitored for the removal of organics, nutrients, and PhACs. A significant variation (p < 0.05) in the pollutant’s removal was observed with the four supporting materials. The synergistic interaction among AAC blocks, macrophytes, and microbial population in the system exhibited higher removal of COD, TN, TP, and PhACs as 88.6%, 81.6%, 77.6%, and 95.3%, respectively. In addition, the estimated PhACs mass balance corroborated that biodegradation (80.57–93%) dominated over sorption and phytodegradation in the CWs. The abundance of Proteobacteria, Bacteroidetes, Actinobacteria, and Planctomycetes in enriched consortia contributed to the degradation of PhACs. Owing to the highly porous nature of waste AAC blocks, a relatively higher microbial activity was observed in the CW unit with AAC as substrate material.

Evaluation of the optimum value of lightweight expanded clay aggregate incorporation into the roller-compacted concrete pavement through experimental measurement of mechanical and thermal properties

ABSTRACT The mechanical and thermal properties of roller compacted concrete pavement (RCCP) are considerably influenced by its aggregate. This study determined the optimum value of lightweight expanded clay aggregate (LECA) incorporation into the RCCP through the response surface methodology (RSM) with mechanical and thermal properties evaluation. LECA was replaced as coarse aggregate in different percentages of 25, 50, 75, and 100% (by volume) to develop lightweight and high-insulation capacity RCCP, which could be appropriate for cold climatic zones. Two different mixtures of RCCP with normal-weight aggregate comprising 12% and 15% cement were used as control mixtures. The results showed that incorporating LECA at any percentage in RCCP produced more workable concrete. The substitution of LECA in 25–100% decreased the density of RCCPs containing 12% and 15% cement about 8–24% and 7–23%, respectively, while the water absorption increased around 4–77% and 8–72%. The thermal conductivity of RCCPs decreased by increasing the LECA replacement as coarse aggregate. Also, the LECA replacement increment in RCCPs resulted in lower heat capacity values. Overall, it can be concluded that incorporating LECA in RCCP by around 37% as coarse aggregate would satisfy the standards in terms of fresh, mechanical, and thermal properties.

Physical filtration of nutrients utilizing gravel-based and lightweight expanded clay aggregate (LECA) as growing media in aquaponic recirculation system (ARS)

The aquaponic recirculation system (ARS) combined aquaculture and hydroponic systems in a mutually beneficial environment. In this study, African catfish, Clarias gariepinus with Butterhead lettuce, Lactuca sativa were cultivated to evaluate gravel-based media and lightweight extended clay aggregate (LECA) as a physical filtration in the nutrient's removal. The performance of both tested growing media was assessed through the reduction of nutrient concentrations in the circulated water, which were total ammonia nitrogen (TAN), nitrite-nitrogen (NO2--N), nitrate-nitrogen (NO3--N), and phosphorus (PO43--P). Statistically, there were significant differences in the percentage of nutrient removal between gravel-based media and LECA treatment for TAN, NO2--N, NO3--N, and PO43--P. TAN removal efficiency achieved 92.47 ± 1.03% in LECA compared to 61.26 ± 2.69% in gravel-based media. For NO2--N, the removal efficiency was 77.25 ± 1.47% and 22.43 ± 6.84% in LECA and gravel-based media. The removal efficiency of NO3--N on LECA was two times more than gravel-based, 60.03 ± 1.58% and 30.77 ± 1.54%. The removal efficiency of PO43--P was 64.29 ± 1.82% for LECA while 27.43 ± 1.62% for gravel-based media. In addition, L. sativa yield was significantly higher in LECA with 64,961.71 ± 1295.61 g/m² as compared to 31,0582.82 ± 877.07 g/m² in gravel-based media. Significantly higher SGR of C. gariepinus in LECA with 3.94 ± 0.11%/day compared to 3.10 ± 0.12%/day in gravel-based media. LECA is an adsorptive substrate with a high removal capacity for phosphorus and nitrogen in aquaculture wastewater, increase its use as growing media in ARS or hydroponics.

Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures

This research provides an experimental investigation on the properties of fiber reinforced composite materials consisting of lightweight expanded clay aggregates (LECA) and polyvinyl alcohol (PVA) fibers. The influence of temperature (room temperature, 250°C, and 500°C) on the lightweight geopolymer mortar (LWGM) composite materials is also explored. LECA is used as a partial replacement to river sand with 60% and 80%. The base material utilized for LWGM is slag activated by a mixture of sodium silicate and sodium hydroxide solutions. The fresh properties in terms of workability and density were performed. A series of experiments, such as compression, flexural and uniaxial tensile strength tests, were executed to assess the mechanical properties of LWGM composite materials. In addition, the microscopic variations due to the elevated temperature were also evaluated by scanning electron microscopy (SEM) to understand the macro-scale behavior of the samples. The results indicated that increasing the level of LECA replacement caused a reduction in the density and compressive strength of the LWGM. Also, incorporating a 1% PVA fiber volume fraction significantly enhanced the flexural and uniaxial tensile behavior of LWGM composite materials. The compressive strength enhancements were observed at 250°C due to further geopolymerization, while compressive strength reductions were obtained at 500°C due to the vapor impact and difference in thermal expansion. In addition, the load-carrying capacity of all samples increased, and displacement capacity decreased under flexural tests at 250°C. However, the ductile behavior of the PVA incorporating specimens changed to brittle due to the melting of PVA fibers.