Dry Compressive Strength Research Articles

Foamed concrete produced from CO2/N2 foam stabilized by CaCO3 nanoparticles and CTAB

Foamed concrete (FC) has garnered popularity, especially with the growing demand for energy-efficient and sustainable construction materials. The stability of the FC slurry as it sets is crucial to the uniformity of the pore structure and, subsequently, FC performance. This study investigates the stability of a novel FC produced using aqueous CaCO3 nanoparticle (NP)/hexadecyltrimethylammonium bromide (CTAB) foam. The effect of NPs and gas type (pure N2, pure CO2, and a 2:1 gas mixture of CO2/N2) on the FC dry density, compressive strength, water absorption, macro- and microstructure, hydration products, and thermal insulation is explored. The results show that the dry density of FC increases with the inclusion of CO2 owing to gas liberation during mixing with the paste leading to less voids. Using the gas mixture, CaCO3/CTAB foam increases the compressive strength of the FC by 38% compared with CTAB alone owing to enhanced uniformity of the pore structure and a denser hydrated paste skeleton. Such structure leads to less connected pores, which reduces atmospheric carbonation, and improves thermal insulation performance. A 2-fold decrease in the largest pore size and a 25% decrease in surface temperature when exposed to an open flame are also achieved in the presence of CaCO3 NPs.

Mechanical properties of on-site manufactured stabilised compressed earth blocks: an experimental investigation and proposed models

ABSTRACT The interest in earth construction is growing increasingly as society becomes more aware of the importance of sustainable building. A considerable number of investigations have been devoted to studying the mechanical properties of compressed earth blocks (CEBs). However, most of these studies were conducted in laboratory settings. Little focus has been directed at studying the performance of CEBs that use on-site soil and other local materials to construct small-scale housing at the same location. A total of 120 CEBs were manufactured on-site from four block mixes: coarse soil with and without Phragmites Australis (Phragmites) and fine soil with and without Phragmites. By comparing the results achieved with minimum strength requirements from different building codes, the dry compressive strengths of all four block mixes were deemed adequate for single-storey structures. The addition of Phragmites caused a slight increase in the compressive strength and a slight decrease in the flexural strength of the CEBs. A formula to estimate the flexural strength of the blocks given the compressive strength is proposed based on a database of test results from the literature and this investigation’s results. CEBs can create a sustainable building solution, especially in remote areas and Indigenous communities with limited access to conventional building materials.

Valorisation of municipal solid waste incinerator bottom ash for the production of compressed stabilised earth blocks

This research centres its attention on the valorisation of incinerator bottom ash derived from municipal solid waste with the aim of producing compressed stabilised earth blocks. Compressed stabilised earth blocks is prepared with 6–12% cement and 10–40% MSWIBA, whose performance is assessed in terms of strength and durability. This includes several properties of compressed stabilised earth blocks, including dry compressive strength, flexural strength, tensile strength, water absorption, wetting-drying cycle, ultrasonic pulse velocity and acid attack. The findings indicate that the inclusion of municipal solid waste incinerator bottom ash as a 20% replacement of soil enhances the compressive strength and ultrasonic pulse velocity of the blocks. Nevertheless, the excessive use of municipal solid waste incinerator bottom ash (beyond 20%) results in an augment of void content and a reduction in compressive strength. The results of the study suggest that the usage of municipal solid waste incinerator bottom ash in the blocks leads to the enhancement of their aesthetic qualities. The study employing scanning electron microscopy indicates an excessive quantity of ettringite crystals in the samples derived from ash of quantity beyond 20%. This is because these samples have higher porosity, which enables the acidic medium to penetrate samples easily and react with the cement hydration products. Hence, though showing less discolouration on the surface, these samples show a significant reduction of compressive strength at the end of the testing regime. Similar results were obtained for the wetting and drying test as well. Therefore, this study recommends a maximum usage of 20% municipal solid waste incinerator bottom ash as a replacement for soil.

INFLUENCE DU PLASTIQUE RECYCLE DE TYPE POLYPROPYLENE SUR LES CARACTERISTIQUES DU BITUME ET DE LENROBE BITUMINEUX

Asphalt is the most widely used product in the construction of flexible pavements. The purpose of this study is to evaluate the feasibility of incorporating recycled polypropylene plastic into bitumen to obtain modified asphalt to manufacture modified asphalt mixes that offer better properties than conventional asphalt mixes. A type of asphalt mix has been studied, a semi-grained asphalt concrete (SGAC14). Conventional asphalt mixes as well as asphalt mixes containing 2% and 4% of the polypropylene dosages were manufactured. For all the tests carried out, the performance was evaluated according to five criteria: 1) improvement of the rheological properties of the bitumen (ring balls, penetrability, softening point, ductility) 2) suitability for compaction with the gyratory shear press (GCP) 3) Water resistance 4) rutting resistance and 5) the Marshall Trial. The experimental results showed, among other things: an improvement in the rheological properties of the modified bitumen for the respective polypropylene assays of 1%, 2%, 3%, 4% and 5%. For these assays, respectively, penetrability decreased by 29%, 37%, 42%, 74%, and 90% the temperature of beads and rings increased by 0.73%, 2.94%, 5.5%, 6.24% and 9.17% the springback increased by 13.82%, 21.40%, 5.69% and 4.07%. . The modified asphalt mixes with 2% and 4% polypropylene compact better than the reference asphalt at 80 gyrations with respectively 5.5% and 5.1% voids we have 6.1% voids for the reference asphalt. An increase in water resistance for polypropylene dosages at 2% and 4% respectively the latter offer a variation in simple dry compressive strength of 4.84%, 22% and a variation in compressive strength after 7 days of immersion in water of 8.53%, 19.5%. Improved rutting performance of modified asphalt mixes: The SGAC14 class 0 reference asphalt mixes are upgraded to a class 1 and class 2 SGAC0/14 for 2% and 4% polypropylene dosages respectively. Modified asphalt mixes give the best Marshall stability. Overall, the possibility of incorporating polypropylene into SGAC14 type asphalt has been proven.

Experimental Study on MgO-Na2CO3 Combined Excitation Recycled Fine-Powder-Slag Cementitious System and Modification

The hydration mechanism and strength development of alkaline salt-activated cementitious materials primarily rely on the alkaline activators and mineral admixtures employed. However, the impact of increased Mg2+, Al3+, and Si4+ resulting from the addition of MgO and steel slag (SS) on the hydration mechanism of these systems remains undetermined. This study delves into the hydration mechanism and mechanical properties of a Na2CO3-MgO-activated regenerated micropowder-slag-based cementitious material system. Mechanical properties were assessed by measuring dry shrinkage and compressive strength at various ages, up to 28 days. The reaction mechanism was scrutinized using X-ray diffraction and a thermogravimetric analysis. The main reaction products contributing to the strength development are C-S-H, C-(A)-S-H gel, and hydrotalcite. Other carbonate-containing phases make smaller contributions. The findings reveal that when SS usage is at 10%, it yields higher early strength compared to ordinary samples. Samples incorporating MgO and SS achieved strengths similar to or surpassing those of the control samples. A noteworthy observation is the synergistic excitation effect between sodium carbonate (NC) and MgO, leading to the generation of a significant amount of gelling substances. These substances fill the pores of the structure, resulting in the formation of a dense microstructure. Consequently, the enhanced interaction between NC and MgO contributes to the overall strength development of the cementitious material.

Developing Low Cost Eco-friendly Restoration Mortars for Historic Lime-based Stucco and Building Materials

In this work, three formulations based on hydrated lime and eco-friendly additives of powdered brick, fly ash and silica fume were designed to improve repair mortars for historic lime-based stucco and building materials. The microscopic features, physical-mechanical behavior and the microstructure of the prepared mortars were evaluated before and after artificial ageing (by humidity/drying cycles and salt weathering). However, a significant mechanical enhancement was reported for the studied mixes, but the silica fume mix showed a notable failure after salt ageing. The fly ash mix revealed the highest bulk density ratio (1.172 g/cm3) compared to the lime and silica fume mixes. The silica fume mix recorded the lowest percentage of water absorption (35.56%) and apparent porosity (28.11%). Further, the silica fume mix yielded the highest dry compressive strength value (22.19 kg/cm2), with an increase reached 31% when compared to the standard lime mix. The results demonstrated that the fly ash mortar is more compatible for sustainable restoration procedures of historic lime-based structures in respect of the physical-mechanical properties.

Study on the properties of autoclaved aerated concrete with high content concrete slurry waste

Concrete slurry waste is solid waste produced in the ready-mixed concrete industry, which will cause serious pollution to the environment. This paper mainly studies the physical and mechanical properties and microscopic products of autoclaved aerated concrete with high content concrete waste slurry. Attempts are made to improve the mechanical properties of the product by using nano-silica and silica fume. The flowability and gas foaming characteristics of the slurry, the dry density, the compressive strength, and the reaction product of the product were analyzed. The experimental results show that with the content of concrete slurry waste reaching 60%, the dry density and compressive strength of AAC are 470.5 kg/m3 and 2.16 MPa, respectively. On this basis, the dry density and compressive strength of AAC with the addition of 1% nano-silica and 7% silica fume are 512.8 kg/m3, 3.05 MPa, and 462.52 kg/m3,2.86 MPa, respectively.

The Effect of Incorporating Juncus Fibers on the Properties of Compressed Earth Blocks Stabilized with Portland Cement

This study investigates the impact of incorporating Juncus fibers (JF) into compressed earth blocks (CEBs) stabilized with varying Portland cement contents, aiming to enhance local construction materials’ performance and reduce housing costs. CEB composites were produced with soil stabilized using different cement contents (4%, 8%, and 12% by weight) and JF reinforcement (0 to 0.2% by weight), compressed at 10 MPa with a hydraulic press. After 28 days of drying, the CEBs underwent diverse experimental characterizations to assess their physical, mechanical, thermal, and durability properties. The results revealed that incorporating JF led to a reduction in unit weight, ultrasonic pulse velocity (up to 36%), and dry compressive strength (approximately 17%). Higher fiber content correlated with increased water absorption and an increased capillarity coefficient. Thermal conductivity analysis indicated improved thermal performance, decreasing from 0.4350 W/m·K (12% cement without fibers) to 0.2465 W/m·K (4% cement with 0.2% JF). Despite the decrease in mechanical strength, CEBs with lower cement (4%) and higher fiber content (0.2%) demonstrated satisfactory durability (abrasion and erosion) and thermal insulation properties. This research suggests the potential of this material as a promising composite for the building materials industry. The findings contribute valuable insights into sustainable construction materials and have implications for cost-effective housing solutions.

Sustainable utilization of fly ash for phase-change geopolymer mortar reinforced by fibers

The utilization of geopolymer mortar (GPM) made from fly ash (FA) as a sustainable construction material with minimal carbon footprint is a viable option. Incorporating microencapsulated phase change materials (mPCM) into GPM presents a promising solution to reduce the energy consumption of buildings. In this study, phase-change GPM (PC-GPM) was manufactured using FA as the main raw material. The thermal conductivity and latent heat of PC-GPM were improved through addition of mPCM, and the mechanical properties were enhanced through inclusion of basalt fiber (BF) and polypropylene fiber (PF). The mineral components and microstructural characteristics of PC-GPM reinforced by fibers were also investigated. The results indicate that an increase in the mPCM content led to a reduction in the dry density and compressive strength of PC-GPM. The addition of mPCM contributed to an increase in water absorption and a reduction in thermal conductivity. The physical-mechanical properties of PC-GPM were dependent on the content, length and type of fibers. The latent heat of PC-GPM was observed to be approximately 7.7kJ/kg. The formation of sodium-alumina-silicate-hydrate (N-A-S-H) and calcium-alumina-silicate-hydrate (C-A-S-H) gels was found to enhance the mechanical properties of PC-GPM. The PC-GPM sample achieved a maximum compressive strength of 36.86MPa, associated with a thermal conductivity of 1.198W/(m·K) when the mPCM and BF contents were 25% and 0.75%, respectively. The experimental findings can offer valuable contributions to the advancement of environmentally friendly and sustainable phase-change building materials.

Effects of Recycled Expanded Polystyrene Beads on the Mechanical and Physical Properties of Cement-Stabilized Compressed Earth Bricks

Nowadays, research on environmentally friendly materials has become a significant challenge in the field of civil engineering. In this study, stabilized compressed earth bricks (CEBs) incorporating recycled expanded polystyrene (EPS) beads were studied with the aim of enhancing the development of green constructions. The mass contents of recycled EPS in CEB formulated at a compaction pressure of 5 MPa are 0%, 0.25%, 0.5%, 0.75%, and 1% relative to the mass of the soil, while cement type CEM I 32.5, as a stabilizer, constituted 8% by mass. Characterization was carried out by determining densities, dry and wet compressive strength, flexural strength, total water absorption, and capillarity. Sample properties were found to be strongly influenced by the percentage of recycled EPS. Increasing the EPS aggregate content led to a reduction in compressive strength in both wet and dry conditions. Samples with 0.5% EPS and 8% cement offered better physical and mechanical performance. Samples containing EPS had relatively low water absorption, which would contribute to good durability. These CEBs comply with the wall construction requirements for two-story dwellings. This study also demonstrates the potential use of this recycled material in the construction industry.

Whole solid waste inorganic lightweight material: Preparation and effects of various parameters on its properties

Flammable conventional organic foam materials imply fire hazards to constructions and buildings. Given that the accumulated alkaline solid wastes, such as red mud (RM) and carbide slag (CS), seriously damage the ecology, their safe utilization in developing nonflammable inorganic foam building materials is very lucrative. This study produced whole solid waste inorganic foam materials through chemical foaming, with aluminum powder used as a foaming agent. This preparation process was optimized by studying the effects of aluminum powder content, water-binder ratio, and stirring water temperature(Water temperature used in the experiment) on the absolute dry density, compressive strength, porosity, pore morphology, and pore size distribution of the specimens. The increase in aluminum powder content and water-binder ratio lead to a decrease in density and compressive strength, while the rising stirring water temperature resulted in opposite trends in porosity and compressive strength. The optimal experimental parameters (aluminum powder content of 1 %, water-binder ratio of 0.7 wt%, and stirring water temperature of 40℃) provide the foam specimen’s porosity of 33.2 %, compressive strength of 0.41 MPa after 28 days, and a dry density below 0.5 g/cm3.

The influence of water-saturation on the strength of volcanic rocks and the stability of lava domes

The rocks forming a volcanic edifice or dome are typically saturated or partially-saturated with water. However, most experiments aimed at better understanding the mechanical behaviour of volcanic rocks have been performed on dry samples, and therefore most large-scale models designed to explore volcano stability have used parameters representative for dry rock. Here, we present a combined laboratory and modelling study in which we (1) quantified the influence of water-saturation on the mechanical behaviour of variably altered dome rocks from La Soufrière de Guadeloupe (Eastern Caribbean) and (2) used these new data to investigate the influence of water on dome stability. Our laboratory data show that the ratio of wet to dry uniaxial compressive strength (UCS) and Young's modulus are ∼0.30–0.95 and ∼0.10–1.00, respectively. In other words, the dome rocks were all mechanically weaker when water-saturated. Further, the ratio of wet to dry UCS decreased with increasing alteration (the wt% of secondary minerals in the rocks). Micromechanical modelling suggests that the observed water-weakening is the result of a decrease in fracture toughness (KIC) in the presence of water. The ratio of wet to dry KIC also decreases with increasing alteration, explaining why water-weakening increased as a function of alteration. To explore the influence of water-saturation on lava dome stability, we numerically generated lava domes in Particle Flow Code using the experimental data corresponding to unaltered and altered rock under dry conditions. The strength of the dome-forming rocks was then reduced to values corresponding to wet conditions. Our modelling shows that, although the stability of the unaltered dome was not influenced by water-saturation, larger displacements were observed for the wet altered dome. Additional simulations in which we modelled a buried alteration zone within an otherwise unaltered dome showed that higher displacements were observed when the dome was water-saturated. We conclude that (1) the water-saturation reduces the UCS and Young's modulus of volcanic rock, (2) larger decreases in UCS in the presence of water are observed for altered rocks, and (3) the stability of a dome can be compromised by the presence of water if the dome is altered, or contains an altered zone. These conclusions highlight that the degree of alteration and water-saturation should be mapped and monitored at active volcanoes worldwide, and that large-scale models should use values for water-saturated rocks when appropriate.

Effectiveness of waste concrete powder in fabricating compressed stabilized earth blocks: Strength, durability and thermal assessment

The construction industry's rapid expansion has led to the accumulation of substantial quantities of waste concrete powder (WCP), which constitutes a significant portion of construction and demolition waste. This study seeks to explore the potential of utilizing WCP in conjunction with cement to manufacture compressed stabilized earth blocks (CSEB) with enhanced mechanical properties. CSEB has long been recognized as an environment-friendly and viable alternative to traditional building blocks that harm the environment. By incorporating WCP into the production process, we can achieve recyclability and sustainability in our construction practices. In order to identify the optimal amount of stabilizers, 15 different combinations of cement and WCP were considered. These included three cement contents (4%, 6%, and 8% by weight of dry soil) and five waste concrete powder (WCP) contents (0%, 5%, 10%, 15%, and 20% by weight of dry soil). Compressed stabilized earth blocks (CSEB) performance was evaluated in terms of strength, durability, and thermal properties. Strength characteristics were determined through unconfined compression and flexure tests, while durability characteristics were evaluated using water absorption, wet compressive strength, submersion, and efflorescence tests. CSEBs without WCP displayed a maximum dry compressive strength of 6.67 MPa, while those with optimal WCP replacement reached a higher strength of 10.68 MPa using the same cement amount. Comparable outcomes were seen in the flexure test, with optimal WCP replacement resulting in a peak strength of 1.92 MPa compared to 1.12 MPa without WCP. In terms of durability, WCP-absent samples showed 13% water absorption, reduced to 10.5% with higher WCP content. Wet compressive strength was relatively lower for all samples, but those with optimal WCP performed best at 4.83 MPa. These fabricated samples also exhibited no efflorescence or damage from submersion. Thermal conductivity, determined using the simplified Lee's method, demonstrated a gradual increase in conductivity as WCP content was increased. However, the obtained values remained within comparable range of fired clay bricks. Furthermore, to investigate the supplementary cementitious behavior of WCP in CSEB, microstructural and thermal analyses were conducted. Scanning electron microscope images revealed a higher concentration of C–S–H gels in the 20% WCP-8% cement combination. The findings suggest that CSEB blocks stabilized with WCP could help to reduce construction and demolition waste while also providing a more stable and sustainable alternative to traditional building blocks.

Preparation of foam concrete from solid wastes: Physical properties and foam stability

The method for preparation of foam concrete from solid wastes were proposed in this study, where soda residue (SR), calcium carbide slag (CS), grand granulated blast-furnace slag (GGBS) and fly ash (FA) were used as raw materials for the binder and Al powder was used as the foam agent. The effects of Al powder, stabilisers and FA content on the dry density as well as compressive strength were assessed to determine the optimal mix proportions. Moreover, to understand the foaming process, the influence of stabilisers on the zeta potential and surface tension of the fresh mixes were measured and Low-Field Nuclear Magnetic Resonance (LF-NMR) was employed to qualitatively characterize the pore size distribution. Finally, the hydration products were analyzed by X-Ray Diffraction (XRD), Fourier transform infrared spectrometer (FTIR), Thermogravimetric Analysis-Differential scanning calorimetry (TGA-DSC), Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDS). The results suggested that the optimal content of Al powder was 1–2%, and the combination of S and P (SP) stabilisers showed better stabilization effect than the single use of S or P, leading to well distributed foam with smaller size. The stabilization effect was attributed to the dissolved negative complex that absorbed on the foam film to increase the repulsion between foams as well as to reduce the surface tension of the fresh mixture. The substitution of GGBS by FA generally resulted in reduced dry density and compressive strength, while the extent varied with the addition of stabilizers, and thus the optimal amount of FA depended on the selection of stabilisers. Overall, our study highlighted the potential of using industrial waste materials for producing sustainable light weight concrete with satisfactory dry density and compressive strength.

Investigation of mechanical properties of phosphorus building gypsum modified by multi-walled carbon nanotubes

This study delves into the multifaceted effects of multi-walled carbon nanotubes (MWCNT) incorporation on phosphogypsum's properties. We investigated the phase composition and morphology of phosphogypsum and observed the influence of MWCNT on the setting time, flexural strength, compressive strength, water resistance, and hydration process. The results demonstrated that MWCNT significantly abbreviates the setting time of phosphogypsum, enhances its absolute dry flexural strength and compressive strength, and improves water resistance, with optimal effects occurring at a MWCNT content of around 1.00%. Nonetheless, these benefits diminish and can even be counterproductive if MWCNT content is excessively high. The enhanced properties of phosphogypsum upon MWCNT addition can be ascribed to the filling effect and mechanical interlocking facilitated by MWCNT. Additionally, MWCNT promoted the hydration of phosphogypsum, as evidenced by calorimetric measurements.

Some properties of thermal insulating cement mortar using Ponza aggregate

Abstract Lightweight aggregate (LWA) mortar is made using lightweight or low-density aggregate, which improves properties such as thermal insulation, durability for freezing and thawing, fire and temperature resistance, and sound insulation. This research aims to use lightweight fine aggregate obtained from crushing natural rocks that are locally called “Ponza” to produce LWA mortar with different mix proportions to study the possibility of using it to produce blocks that can be erected on the outer side of the walls of old buildings to provide good thermal insulation. It also presents a study about the internal curing property of the produced cement mortar, which comes from the absorbed water by the used surface-saturated dry Ponza aggregate. The process includes using three mix proportions (1:1, 1:0.7, and 1:0.5) by weight of cement: fine aggregate. The samples were cured by dividing them into five groups, including moist curing for 1, 3, 7, and 28 days and the fifth group was moist cured for 1 day and then covered by a thin layer of flan coat. Dry density, compressive strength, flexural strength, and thermal conductivity for ages (7, 28, and 56 days) have been tested. The findings indicate that it is possible to produce thermal insulating lightweight cement mortar with mixtures of 1:0.7 or 1:0.5 cement to LWA, using Ponza aggregate, since the results showed an acceptable range of compressive and flexural strengths reaching about 14.75 and 2.91 MPa, respectively, a bulk density of less than 1,600 kg/mm3, and a lower thermal conductivity than many building materials.

Strategy for the Mix Design of Building Earthen Materials Made of Quarry By-Products

The use of quarry by-products can enable the commercialization of a clay building material (reconstituted earth) thanks to minimal valorized and perennial stocks of materials. This study shows that quarry by-products can be used to mix design a clay-based building material for the manufacture of CEB. These soils are composed of quarry tailing and clayey muds. Proctor and dry compressive strength tests have shown that the proportion of mud that achieves the highest possible compressive strength is a balance between increasing density through the aggregate arrangement, increasing clay activity, and decreasing density through the increase in water content. These tests resulted in the formulation of materials with compressive strengths of 5.8 MPa and 8.4 MPa at densities of 2135 kg/m3 and 2178 kg/m3. The influence of mud incorporation on the material granulometry and on its characteristics was also studied. Moreover, a model allowing us to link the compressive strength, the clay activity, and the dry density is proposed for the materials composed of quarry by-products. This model enables us to facilitate the mix design and the standardization of the earth material.

Degradation of physico-mechanical properties and damage mechanisms of sandstone under the combined action of freeze–thaw cycles, chemical solution, and compressive stress

Rocks in cold regions subjected to freeze–thaw cycles are often affected by the surrounding hydro-chemical solutions and external load. In this study, the evolution of physical and mechanical characteristics and the damage mechanism of sandstone under the combined action of freeze–thaw cycles, chemical solution, and compressive stress were investigated. A series of quick cyclic freeze–thaw tests in different chemical solutions and stress levels were conducted. The dry mass, wave velocity, and compressive strength decrease as the number of freeze–thaw cycles increases. The variations in dry mass, wave velocity, and rock appearance indicate that lower stress levels (<0.5σ0, σ0 is the saturated uniaxial compressive strength of the original specimen) can limit the effect of repeated freeze–thaw cycles and chemical corrosion, whereas higher stress levels (>0.5σ0) can exacerbate the combined effect on rock damage. In addition, a modified decay model is proposed that incorporates the initial properties and residual integrity of the rock to describe the evolution of rock strength and wave velocity. Both the residual strength and wave velocity of sandstone are constants that are independent of stress level and chemical solution. The degradation rate of compressive strength increases abruptly at higher stress, whereas that of wave velocity generally decreases with increasing stress level. The continuous action of the cyclic frost-heaving force, hydrolysis and chemical corrosion, and external compressive stress promote generation and propagation of pores and microcracks, causing deterioration of the mass, wave velocity, and compressive strength.

Optimizing the mechanical behavior of clay using cement and PVC aggregates with the application of a mixture design method

The present research work aims to use the mix design approach to develop some models that can predict the mechanical properties of clayey soil. For that, the proctor compaction test, direct shear test, and uniaxial compression test were performed on bentonite (B) and other mixtures incorporating different proportions of polyvinyl chloride (PVC) aggregates stabilized with cement (C). The experimental and modeling results indicated that a good correlation existed between the three factors (B, C, and PVC) and the values of the maximum dry density, cohesion, and compressive strength responses. It was also found that the majority of models gave relatively good correlation coefficients (R2 ≥ 0.90) for all the responses under study. The results obtained indicated that this bentonite had a compressive strength 180.24 kPa, with a cohesion 64.71 kPa, and a maximum dry density equal a 1.571 gr/cm3. In addition, the experimental and modeling findings showed that the mixture including C (55% ± 10%), PVC (35% ± 10%), and B (10% ± 10%) exhibited a quite high cohesion of 103 kPa (more than one and half times that of unreinforced samples), while the highest compressive strength of 445 kPa (two and half times more than that of unreinforced samples) was obtained for the mixture comprising of C (50% ± 10%), PVC (25% ± 10%) and B (25% ± 10%). In addition, it turned out that these results are very encouraging in terms of environmental protection because this technique allows recycling and valorizing huge quantities of PVC waste produced throughout the world. It has been revealed that PVC wastes can be utilized in the geotechnical field to improve the mechanical behavior for clay soils, and to assess the values of maximum dry density, cohesion, and compressive strength of mixtures not made in the laboratory using the derived statistical models.

Evaluation of the lightweight foamed concrete characteristics

The purpose of this paper is to assess the properties of light weight foamed concrete. In this research, two phases are investigated. The first stage explored the characteristics of fresh and hardened foamed concrete using a foaming agent. The following parameters were employed in this study: foaming agent used as a volume of concrete mix by 10, 20, and 40%, fly ash used as a replacement of cement content by 10, 25, and 50%, and polypropylene fiber used with varied volume fractions of 0.5, 0.75, and 1.0%. Slump values are applied to evaluate the fresh properties. To evaluate the hardened concrete, the dry density and compressive strength at 7 and 28 days are computed. Furthermore, the 28-day tensile splitting strength and flexural strength are studied. The effect of a high temperature was evaluated. The second stage investigated the effects of polypropylene fiber on both fresh and hardened concrete. It was observed that foaming agents improve fresh characteristics while decreasing compressive strengths and dry density. Furthermore, utilizing fly ash improves the characteristics of both fresh and hardened foamed concrete. The fiber reduces the fresh characteristics while enhancing the toughened properties. Because of its low density, foamed concrete is being used for structural applications because of this study. Such as those utilized for thermal insulation, acoustic impedance, and fire breaks. Also used to create road foundations for roads built on soft soil.