10 research outputs found
Physical and Mechanical Effects of Silica Sand in Cement Mortars: Experimental and Statistical Modeling
No full textThe environmental impacts of cement manufacturing are becoming a real-time issue that requires attention. This paper investigates the mechanical and physical properties of mortars with finely ground sand as a substitute for cement. The experimental program consisted of three silica sands with a Blaine Specific Surface (BSS) area of 459 m2/kg, 497 m2/kg, and 543 m2/kg and four substitution ratios of 10%, 20%, 30%, and 40%. A total of 12 mixtures have been prepared and tested for comparison to the reference mortar. The pozzolanic effect of the sand was evaluated using thermogravimetric analysis (TGA). The results revealed that the fineness variation from 459 m2/kg to 543 m2/kg resulted in an increase of 20% and 30% in water absorption and compressive strength, respectively. However, increasing the substitution ratio from 10% to 40% led to a 40% decrease in mechanical strength and a 25% increase in water absorption. The statistical analysis of the results demonstrated that both factors under study influenced compressive strength and water absorption. The ANalysis of VAriance (ANOVA) confirmed that the proposed regression equations predict the experimental results. Further studies will investigate both the technical and environmental performances of cement mortars with finely ground silica sand
Contribution à la reconnaissance du sol par tomographie électrique
No full textLes méthodes électriques par courant continu en géophysique, ont pour objectif de déterminer les propriétés électriques du sol par la mesure de sa résistivité. La technique de tomographie électrique est la reconnaissance multi-dimensionnelle des propriétés électriques intrinsèques du milieu étudié. En géophysique, cette technique permet de traduire les données acquises en surface ou en sub-surface en une image interprétable en termes géologique. La tomographie électrique est fréquemment employée dans différents domaines (géologie, hydrogéologie, génie civil et environnement, etc.).
Notre travail est basé sur l'utilisation de la méthode dite: la résistivité de tomographie électrique selon l’acquisition 2D. D’une part, pour tester la capacité de la méthode de tomographie électrique, afin de localiser et de déterminer les cavités souterraines dans le proche sous-sol et la caractérisation du sol par des mesures in situ, et d’autre part pour faire des comparaisons par simulation numérique. En utilisant les logiciels Res2Dmod et Res2Dinv, pour différents dispositifs d’électrodes de mesure utilisés en tomographie électrique (Wenner, Dipôle-dipôle, Pôle-dipôle, Pôle-pôle, Schlumberger et Gradient). Les cavités modélisées ont des sections circulaires et rectangulaires avec différentes résistivités du milieu encaissant, ainsi que d’évaluer le comportement de ces dispositifs d’électrodes et déduire leurs avantages et leurs inconvénients.
L'étude a conclu que cette technique de tomographie électrique est efficace et a montré son efficacité pour la reconnaissance du sol. Les résultats de la modélisation numérique, ont montré que le dispositif d’électrode dipôle-dipôle a donné de bons résultats pour la détection des cavités souterraines dans le proche sous-sol, en l'absence de bruit. Mais, en présence de bruit, les dispositifs d’électrodes: gradient, pôle-pôle et pôle dipôle ont donné de bons résultats
External Confined Concrete Cylinders Behavior under Axial Compression Using CFRP Wrapping
No full textCarbon-fiber-reinforced polymer (CFRP) is a composite material used to mend and strengthen concrete structural elements in civil engineering. The prime aim of this experimental study is to investigate the comportment of confined concrete cylinders (CCC) under uniaxial loads by altering the concrete strength, the CFRP angle orientation, and the volumetric ratio, following the externally bonded reinforcement technique (EBR). We present the results of the confinement effect and failure mechanisms issue of more than 150 specimens of CFRP confined concrete cylinders that have been undertaken and in which several parameters were altered. Totally and partially confined concrete cylinders were tested for failure under axial compressive loads and indirect tensile tests. Four different ratios of water/cement (0.33, 0.36, 0.401, and 0.522) were investigated. In addition, three sand–resin ratios were prepared to improve the mechanical properties and the adhesion of the CFRP and the concrete. The obtained results revealed a clear improvement in the compressive strength of the specimens made with low strength concrete (from 38% to 66%) compared to those made of high strength concrete (from 11% to 31%), where the improvements are relatively low. Furthermore, the transversally confined concrete cylinders presented significant gains in strength over those confined longitudinally. Lastly, adding sand to the resin increases the compressive strength of confined concrete cylinders (1.19% to 54.62%) and reduces the cost of the resin used for fixing CFRP materials
Synergistic effects and optimization of cement kiln dust and glass powder incorporation in self compacting mortar using central composite design
No full textAbstract This study investigates the optimization of self-compacting mortar (SCM) properties incorporating cement kiln dust (CKD) and glass powder (GP) as partial replacements for ordinary Portland cement (OPC). Slump, flow, compressive strength, flexural strength, and porosity were studied by central composite design (CDD) to investigate the impact of CKD and GP (0–25% each). Material variability was understood using statistical models developed from SCM property prediction (R2 = 0.92–0.95). In the case of CKD, the workability generally increased, whereas the workability decreased in the case of GP, especially at the higher levels. Both materials reduced compressive and flexural strengths, with CKD being the most significant contributor. Higher CKD and GP contents increased porosity, proportional to strength losses. The optimum formulation of 7.22% CKD and 5.26% GP, which showed the highest desirability of 0.97, was identified as the optimum formulation with a balance between fresh and hardened properties through the desirability approach. The optimized mixture resulted in a slump (22.98 cm), flow time (11.55 secs), compressive strength (54.33 MPa), flexural strength (8.4 MPa), and porosity (14.49%). The optimized formulation demonstrates significant environmental and economic benefits, reducing CO₂ emissions by 68.15 kgCO₂/t (12.39%) and decreasing material costs by $5/ton (12.4%) compared to the control SCM. This study demonstrates the possibility of integrating CKD and GP in SCM, offering a sustainable alternative to traditional cement-based mortars without significant performance loss
Exploring the Effect of Lime and Cement Ratios on the Mechanical Properties of Clay Bricks Made from Different Types of Soils
No full textThe clay brick industry is facing significant challenges related to improving its physico-mechanical properties and durability performance of sustainable products. The current study aimed to investigate the effect of stabilizers (lime and cement) on the clay brick properties of three soils. The investigated soils were taken from different regions of Algeria. A series of laboratory experiments were carried out to examine the effect of lime and cement addition with different ratios of 2%, 4%, 6%, 8%, and 10%, on the mechanical properties. The assessment was based on compressive strength, flexural strength, total and capillary water absorption tests. The test results showed that the lime addition to soils A and B led to a significant increase in compressive strength (CS) by 47% and 101%, respectively. The highest values obtained were for the 8% ratio. The obtained gain in compressive strength soil C reached its maximum CS at 6% ratio, and the obtained gain was 44%. However, for cement addition, the highest CS values were obtained at the 10% ratio for all studied soils. The observed gains in compressive strength for soils A, B, and C were 24%, 15%, and 33%, respectively. Flexural strength (FS) followed a similar trend, with lime addition improving (FS) by up to 400% for soil A at an 8% ratio. Cement addition also enhanced (FS), with the highest improvement of 103%, which was observed for soil A at a 10% ratio. It was also observed that lime addition significantly decreased the total absorption by up to 36% at an 8% ratio for soils A and B, and at 6% for soil C. In contrast, the total absorption decreased uniformly with the cement addition up to the 10% ratio. The lowest absorption observed at a 10% ratio was 11.95%. Lime addition also decreased the capillary absorption of clay bricks, and the lowest value was observed at an 8% ratio for both soils (A and B) and 6% for soil C. The CA values decreased by approximately 24% for soils A and B and 14% for soil C. In the case of cement addition, it was noted that the capillary absorption had the same pattern as the total absorption. The percentage decreases in CA were 41%, 40%, and 38% for soils A, B, and C, respectively. These results indicate that the enhancement of clay brick was observed for lime addition ranging from 2% to 8%. Therefore, good mechanical strengths were obtained at a 10% cement ratio
Utilizing Residual Industrial Waste as Sustainable Adsorbents for the Removal of Indigo Carmine from Contaminated Water
No full textThe recovery of green waste and biomass presents a significant challenge in the 21st century. In this context, this study aims to valorize waste generated by the fruit juice processing industry at the N’Gaous unit (composed of the orange peel, fibers, pulp, and seeds) as an adsorbent to eliminate an anionic dye and to enhance its adsorption capacity through thermal activation at 200 °C and 400 °C. The aim is also to determine the parameters for the adsorption process including contact time (0–120 min), solution pH (2–10), initial dye concentration (50–700 mg/L), and adsorbent dosage (0.5–10 g/L). The adsorption tests showed that waste activated at 400 °C (AR400) demonstrated a higher efficiency for removing indigo carmine (IC) from an aqueous solution than waste activated at 200 °C (AR200) and unactivated waste (R). The experimental maximum adsorption capacities for IC were 70 mg/g for unactivated waste, 500 mg/g for waste activated at 200 °C, and 680 mg/g for waste activated at 400 °C. These tests were conducted under conditions of pH 2, an equilibrium time of 50 min, and an adsorbent concentration of 1 g/L. The analysis of the kinetic data revealed that the pseudo-second-order model provides the best fit for the experimental results, indicating that this mechanism predominates in the sorption of the pollutant onto the three adsorbents. In terms of adsorption isotherms, the Freundlich model was found to be the most appropriate for describing the adsorption of dye molecules on the R, AR200, and AR400 supports, owing to its high correlation coefficient. Before adsorption tests, the powder R, AR200 and AR400 were characterized by various analyses, including Fourier transform infrared (FTIR), pH zero charge points and laser granularity for structural evaluation. According to the results of these analyses, the specific surface area (SSA) of the prepared material increases with the increase in the activation temperature, which expresses the increase in the adsorption of material activated at 400 °C, compared with materials activated at 200 °C and the raw material
Physical, Mechanical, and Durability Performance of Olive Pomace Ash in Eco-Friendly Mortars
No full textThe cement industry is a major contributor to global CO2 emissions, driving the research for sustainable alternatives. Olive biomass ash (OBA), a byproduct from burning all types of biomass from the olive tree, has emerged as a potential supplementary cementitious material (SCM). This study investigates the effects of incorporating olive pomace ash (OPA) as a partial cement substitute (0% to 50% by weight) on mortar properties over extended curing periods. Workability, compressive and flexural strengths, water absorption, and freeze–thaw resistance were evaluated. Up to 20% OPA replacement improved workability while maintaining acceptable strength and durability. Beyond this level, mechanical properties and frost resistance decreased significantly. Correlation analyses revealed strong relationships between flow time and wet bulk density (R2 = 0.93), an exponential relationship between 28-day compressive strength and water absorption (R2 = 0.87), and linear correlations between pre- and post-freeze–thaw mechanical properties (R2 ≥ 0.99 for both compressive and flexural strengths). The results demonstrate that optimal OPA incorporation enhances mortar performance without compromising structural integrity and provides a viable strategy for valorizing agricultural waste
Impact of Silica Sand on Mechanical Properties of Epoxy Resin Composites and Their Application in CFRP–Concrete Bonding
No full textPremature debonding between carbon fiber-reinforced polymer (CFRP) and concrete is a critical issue in structural reinforcement applications, often leading to a significant reduction in the load-carrying capacity of the system. This failure mode is typically initiated by inadequate adhesion at the interface, compromising the effectiveness of CFRP in enhancing the structural performance of concrete elements. To address these issues, this study explores the impact of silica sand on the mechanical and adhesion properties of epoxy resin composites. Initially, this paper investigates the physical and mechanical properties of epoxy resin composites by varying the ratios of silica sand from 0% to 15% by volume. Subsequently, it examines the effectiveness of these composites as sealing materials to enhance the bond strength between CFRP and concrete. Incorporating a 10% silica content improves the mechanical properties of the epoxy resin, with the tensile strength increasing from 29.47 MPa to 35.52 MPa and an elastic modulus from 4.38 GPa to 5.83 GPa. Furthermore, silica sand enhances the adhesion strength between CFRP and concrete, as confirmed by the increase in the pull-out force from 14.21 kN to 18.79 kN. Silica particles improve surface roughness and interlocking, contributing to a better load distribution and stress transfer at the interface. Therefore, silica-filled epoxy resin is an efficient material for CFRP–concrete bonding applications
Carbon Fiber-Reinforced Polymer (CFRP) Confinement Strategies for Concrete Columns: Evaluating the Efficacy of Full and Partial Wrapping Methods
No full textThis study evaluates the effectiveness of full and partial fiber-reinforced polymer (FRP) confinement techniques on concrete columns, with a focus on carbon fiber-reinforced polymers (CFRP). Experimental results revealed that full CFRP confinement markedly improves both compressive strength and ductility. Specifically, columns fully confined with CFRP exhibited a maximum increase in compressive strength of 89.36% compared to unconfined specimens. In contrast, partial confinement using horizontal strips with a 30 mm spacing resulted in a 49.53% increase in compressive strength, though this was 21.03% less than that achieved with full confinement. Spiral confinement, with spacings of 45 mm and 65 mm, achieved strength increases of 3.03% and 6.58%, respectively, with a maximum enhancement of 21.90% compared to unconfined concrete. Deformation results showed that horizontal strips enhanced ultimate axial deformation by up to 610.78%, whereas spiral confinement improved deformation by 591.42% at 30 mm spacing. The study concludes that horizontal CFRP strips provide superior performance and efficiency for strength enhancement compared to spiral confinement. These findings indicate that partial CFRP confinement is a viable alternative to full confinement, offering substantial improvements in concrete strength and deformation while optimizing material use and installation complexity
Integrated Techno-Environmental Analysis of Finely Ground Silica Sand in Sustainable Mortar Production
No full textThe environmental impacts of cement production are becoming more urgent concerns. This study examined the mechanical characteristics of cement when it is partially replaced with finely crushed sand. The experimental program consisted of three different levels of sand fineness of 459 m2/kg, 497 m2/kg, and 543 m2/kg, as well as four substitution ratios of 10%, 20%, 30%, and 40%. A total of thirteen combinations were formulated and then evaluated. The results demonstrated that increasing sand fineness from 459 m2/kg to 543 m2/kg substantially impacted the compressive strength (CS), increasing it by up to 30%, and increasing the substitution ratio from 10% to 40% reduced the mechanical strength by roughly 40%. An extensive techno-environmental evaluation showed that replacing cement with finely crushed sand is technically feasible and environmentally advantageous. This technique can decrease carbon dioxide (CO2) emissions by around 40%, emphasizing its ecological benefits and coinciding with worldwide initiatives to decrease the environmental impact of construction materials. In summary, this study demonstrates the advantages of improving the mechanical characteristics of cement while minimizing its ecological footprint. It suggests that finely crushed sand can be used as a sustainable alternative in cement manufacturing, promoting the use of more environmentally friendly construction methods
