Key Engineering Materials Vol. 1018

Abstract: In response to the urgent need for more sustainable and environment friendly construction materials, this work explores the viability of partially or fully substituting the traditional glass fibers with date palm leaf fibers in bulk molding compounds (BMC) for infrastructure applications, specifically pedestrian network elements. To achieve this, assessment of mechanical properties across three composite groups was carried out: pure date palm fiber, hybrid (date palm and glass fiber), and pure glass fiber. The compression and flexural strengths of each composite were quantitatively assessed and compared. Results demonstrated that composites solely comprising glass fibers exhibited superior compressive and flexural. Conversely, pure date palm fiber composites showed the lowest strength values. So as expected, significant improvements were observed with glass fiber hybridization, up to 88.59% in compression and 349.21% in flexural strength in comparison to the pure date palm fiber composites. These findings underline the potential of date palm fiber hybrid composites which offers a balance between performance and environmental sustainability. The research also supports Sustainable Development Goals by encouraging low-carbon industrial materials, responsible production, and sustainable resource management.

Abstract: Concrete, a fundamental material in modern construction, is prone to water penetration, which can lead to structural degradation. Conventional waterproofing methods often rely on materials with significant environmental impacts. This study explores the use of wood tar (WT), derived from Eucalyptus wood pyrolysis, as a sustainable waterproofing agent for concrete. The WT was characterized using pH and thermogravimetric analysis (TGA), as well as gas chromatography-mass spectrometry (GC/MS). With a small modification, the WT waterproofing efficacy was tested through contact angle measurements and water absorption by capillary rise within concrete. Results indicated that WT-coated concrete exhibited significantly lower water absorption and demonstrated potential as an eco-friendly alternative to traditional waterproofing methods. Although preliminary results, this research contributes to the development of sustainable building materials, driving innovation to construction practices.

Abstract: The growing issue of light expanded clay aggregate (LECA) disposal has become a pressing environmental concern globally, underscoring the need for swift and effective solutions. To mitigate this issue, the construction industry is increasingly adopting sustainable alternatives to traditional concrete. One such innovative approach involves incorporating these waste materials into construction materials, primarily concrete. This study aimed to create a novel, eco-friendly concrete material utilizing recycled LECA, engineered to float on water. The investigation employed a range of polyvinyl alcohol (PVA) fiber volume fractions (0, 0.15, 0.25, 0.35, and 0.45%) to assess their impact on the strength properties of lightweight foamed concrete (LWFC). The combination of LECA and polyvinyl alcohol (PVA) fibers resulted in compressive strengths ranging from 3.51 to 4.15 MPa, accompanied by densities between 600 and 750 kg/m³. Furthermore, ultra-lightweight foam floating concrete (ULWFFC)-P5 demonstrated enhanced load capacity, with a buoyancy force of 26.5 N. This innovation presents a groundbreaking opportunity for the construction sector, offering a sustainable and effective solution for complex projects in building and offshore marine environments.

Abstract: Experimental techniques like X-ray diffraction (XRD) and pore size distribution determination (MIP), in conjunction with thermodynamic simulation (GEMS) and kinetic modeling of cement hydration (PK), were used to analyze the microstructures and phase compositions of cementitious materials under the coupling effect. This allowed researchers to study the evolution of formation products and pore structure of cementitious materials under the coupling of long-term wet and dry cycling and sulphate erosion. The findings demonstrate that the cement pastes with varying w/b ratios formed the expansion products calcium alumina and gypsum after 180 days of dry and wet cycling by 5% sodium sulphate solution; however, the specimens with lower water-ash ratios had denser structures, fewer erosion products, and better resistance to sulphate erosion. The following illustrates how sulphate erosion products affect the pore structure: during the early stages of erosion, the pore structure becomes more refined and has an increase in the number of transition pores between 10-100 nm due to the erosion products such calcium alumina and sodium sulphate crystals filling the pores. The degree of sulphate erosion is exacerbated by the formation of new cracks and larger macropores, which result in an increase in the number of erosion products, an increase in the average pore size, and a looser pore structure. However, the calcite growing in the transition pores is more destructive, and the crystallisation pressure keeps building up, leading to the destruction of some of the transition pores.