Mechanical, thermal and durable performance of wastes sawdust as coarse aggregate replacement in conventional concrete

Wood yields a number of by-products and Sawdust is as useful as others. Sawdust is regarded as a waste material and is effectively utilised as sawdust concrete in the construction of buildings. It is capable to be utilised as light-weight concrete and holds the quality of long duration heat transfer. In this study, three different ratios (1:1, 1:2 and 1:3) volume mix proportions of cement to sawdust were adopted to make sawdust concrete. At varied intervals of 7, 28 and 56 days of air curing, thermal and mechanical properties like workability, density, elastic modulus, strength and heat transfer were probed of mentioned sawdust concrete proportions. The resistance to elevated temperatures was also evaluated after 28 days of age; weight loss, residual compressive strength, surface texture and ultrasonic pulse velocity were considered in evaluation process. The findings showed that increase in sawdust volume affected to decrease the workability, strength and elevated temperatures resistance. However, the concrete having higher proportion of sawdust performed competently and well in terms of thermal conductivity. Moreover, a decrease in the heat transfer of sawdust was also observed. Examining the all-embracing mechanical and physical properties, sawdust can be effectively utilised in the construction of buildings

Flexural behavior of reinforced concrete beams under instantaneous loading: Effects of recycled ceramic as cement and aggregates replacement

The flexural behavior of five reinforced concrete beams containing recycled ceramic as cement and aggregate replacement subjected to a monotonic static load up to failure was studied. A full-scale, four-point load test was conducted on these beams for 28 days. The experimental results were compared with the conventional concrete as a control specimen. The cross-section and effective span of these beams were (160 × 200 mm) and 2200 mm, respectively. The data recorded during the tests were the ultimate load at failure, steel-reinforcement bar strain, the strain of concrete, cracking history, and mode of failure. The beam containing 100% recycled aggregates displayed an ultimate load of up to 99% of the control beam specimen. In addition, the first crack load was almost similar for both specimens (about 14 kN). The deflection of the beam composed of 100% of the recycled aggregates was reduced by 43% compared to the control specimen. Regardless of the recycled ceramic aggregates ratio, quantities such as service, yield, and ultimate load of the proposed beams exhibited a comparable trend. It was asserted that the ceramic wastes might be of potential use in producing high-performance concrete needed by the structural industry. It might be an effective strategy to decrease the pressure on the environment, thus reducing the amount of natural resources usage

Freeze-thaw cycle and abrasion resistance of alkali-activated FA and POFA-based mortars: Role of high volume GBFS incorporation

Alkali-activated binders made from various waste products can appreciably reduce the emission of CO2 and enhance the waste recycling efficiency, thus making them viable substitutes to ordinary Portland cement (OPC)-based binders. Waste materials including fly ash (FA), palm oil fuel ash (POFA), and granulated blast furnace slag (GBFS) reveal favorable effects when applied to alkali-activated mortars (AAMs) that are mainly related to the high contents of silica, alumina, and calcium. Therefore, fifteen AAM mixes enclosing FA, POFA with high volume of GBFS were designed. The obtained GBFS/FA/POFA-based AAMs were subjected wet/dry and freeze/thaw cycles. The impact of various GBFS contents on the microstructures, freeze-thaw cycle, abrasion resistance, mechanical and durability features of the proposed AAMs were evaluated. The results showed that presence of Ca can significantly affect the AAMs durability features and long-term performance. The abrasion resistance of the AAMs was decreased with the decrease of CaO contents. Furthermore, the abrasion depth of 70% AAMs (0.8 mm) was lower in comparison to the mix made by replacing 50 wt% of FA with GBFS (1.4 mm). Generally, increase in the GBFS contents from 50 to 70% could largely impact the AAMs properties under aggressive environmental exposure. The expansion and physical impacts during the freezing-thawing cycles was argued to destroy the bonds in C–S–H and paste-aggregates, causing the formation of large cracks. It is asserted that the AAM mixes made from FA, POFA and high volume of GBFS may offer definitive mechanical, durable, and environmental benefits with their enhanced performance under aggressive environments

Impact Resistance Enhancement of Sustainable Geopolymer Composites Using High Volume Tile Ceramic Wastes

The need for sustainable concrete with low carbon dioxide emissions and exceptional performance has recently increased in the building industry. Many distinct types of industrial byproducts and ecologically safe wastes have shown promise as ingredients for this kind of concrete. Meanwhile, as industrialization and lifestyle modernization continue to rise, ceramic waste becomes an increasingly serious threat to the natural environment. It is well known that free cement binder that incorporates tile ceramic wastes (TCWs) can significantly improve the material’s sustainability. We used this information to create a variety of geopolymer mortars by mixing TCWs with varied proportions of ground blast furnace slag (GBFS) and fly ash (FA). Analytical techniques were used to evaluate the mechanical properties and impact resistance (IR) of each designed mixture. TCWs were substituted for binders at percentages between 50 and 70 percent, and the resultant mixes were strong enough for real-world usage. Evidence suggests that the IR and ductility of the proposed mortars might be greatly improved by the addition of TCWs to a geopolymer matrix. It was found that there is a trend for both initial and failure impact energy to increase with increasing TCWs and FA content in the matrix. The results show that the raising of TCWs from 0% to 50, 60 and 70% significantly led to an increase in the failure impact energy from 397.3 J to 456.8, 496.6 and 595.9 J, respectively

Flexural behavior of reinforced concrete beams under instantaneous loading: effects of recycled ceramic as cement and aggregates replacement

The flexural behavior of five reinforced concrete beams containing recycled ceramic as cement and aggregate replacement subjected to a monotonic static load up to failure was studied. A full-scale, four-point load test was conducted on these beams for 28 days. The experimental results were compared with the conventional concrete as a control specimen. The cross-section and effective span of these beams were (160 × 200 mm) and 2200 mm, respectively. The data recorded during the tests were the ultimate load at failure, steel-reinforcement bar strain, the strain of concrete, cracking history, and mode of failure. The beam containing 100% recycled aggregates displayed an ultimate load of up to 99% of the control beam specimen. In addition, the first crack load was almost similar for both specimens (about 14 kN). The deflection of the beam composed of 100% of the recycled aggregates was reduced by 43% compared to the control specimen. Regardless of the recycled ceramic aggregates ratio, quantities such as service, yield, and ultimate load of the proposed beams exhibited a comparable trend. It was asserted that the ceramic wastes might be of potential use in producing high-performance concrete needed by the structural industry. It might be an effective strategy to decrease the pressure on the environment, thus reducing the amount of natural resources usage