This paper aims to enhance the effective utilization of construction solid waste renewable brick powder (RBP) and circulating fluidized bed fly ash (CFBFA), addressing the issues of resource consumption and environmental pollution associated with these two types of solid waste. It employs CFBFA to synergistically activate RBP for the preparation of solid waste-based earthwork subgrade backfill. This research examines the impact of RBP and CFBFA content on the performance of earthwork subgrade backfill (ESB), while the microstructure of the paste test block was investigated using XRD, SEM, FTIR, and TG-dTG techniques. The synergistic mechanism of multisolid waste was examined at the micro level, and the appropriate ratio of solid waste-derived lowcarbon ESB was thoroughly assessed. The findings indicate that an increase in the CFBFA content generally enhances the mechanical strength of the paste. At the experimental ratio of RBP: CFBFA: coarse-grained soil = 8: 32: 60, the 28-day unconfined compressive strength (UCS), California Bearing Ratio (CBR) value, rebound modulus value, shear strength value, and compression modulus value of the sample attain their maximums, measuring 5.3 MPa, 41.9 %, 71.9 MPa, 10.5 KPa, and 15.76 MPa, respectively, all exceeding the standard values. The hydration products of cementitious materials based on RBP and CFBFA mostly consist of C-S-H gel, ettringite (AFt), and calcite. The robust honeycomb gel structure, created by the staggered interconnection of C-S-H gel and ettringite, is the primary contributor to mechanical strength. The modified cementitious material, composed of RBP-CFBFA, exhibits effective cementation and solidification properties for heavy metals, achieving leaching concentrations that comply with Class III water standards as outlined in the Chinese standard GB/T 14848-2017.

Reclaimed brick masonry makes up a noteworthy portion of construction and demolition waste (CDW), totaling approximately 31%, even exceeding concrete waste. This study proposes using reclaimed brick masonry to enhance the micro- and macro-properties of clayey soil. Extensive laboratory testing was conducted to evaluate the performance of reclaimed brick powder (BP) along with 5% cement content. The cement was used to generate chemical bonds with BP and soil grains. Micro-testing like XRF, XRD, EDAX, and SEM analyses confirmed the formation of CSH and CAH compounds which strengthened soil structure and enhanced its brittleness. However, after 10% BP, the addition of coarser grains converted the soil structure from dense to porous. Macro-properties assessment confirmed that 10% BP with 5% cement content is an optimum combination for selected soil. The addition of BP reduces the required amount of cement for soil stabilization, making it an eco-friendlier solution. The addition of the optimum combination decreased the wL, IP, FSI, wopt, and Cc and increased the gamma dmax, qu, CBR value, and sigma y significantly. It is also confirmed by the specimen's failure morphology analysis that BP with cement in clayey soil curtailed cement generated brittleness and enhanced ductility.

This study explores the feasibility and benefits of utilizing plastic waste in the production of construction materials, specifically composite bricks. The escalating accumulation of plastic waste poses significant environmental challenges, which necessitates innovative approaches for recycling and re-utilization to mitigate pollution and reduce landfill use. Our research focuses on the synthesis of bricks by incorporating high-density polyethylene (HDPE) and polystyrene (PS) with sand brick powder, utilizing a compatibilizer (SBS-g-MA) to enhance interfacial adhesion and mechanical integrity. The experimental methodology involved the preparation of composite materials through melt mixing, followed by molding to form brick specimens. These were analyzed for their mechanical properties, including tensile strength, Young's modulus, and elongation at break, as well as thermal properties such as degradation temperature and crystallization behavior. Results showed that the inclusion of sand brick powder significantly enhances the thermal stability of the composites, as evidenced by the higher degradation temperatures observed. Specifically, the degradation temperature increased from 300.59 degrees C in pure HDPE/PS blends to 420.39 degrees C in composites with 7% brick powder, suggesting the formation of a protective barrier against thermal decomposition. Moreover, mechanical testing revealed that composites with up to 7% brick powder exhibited improved tensile strength and Young's modulus compared to pure polymer blends.

Dispersive soil is susceptible to water erosion and could cause damage in geotechnical engineering or hydraulic engineering projects. Recycled clay brick powder (RCBP) was used as a modifier to improve the dispersivity and water stability of dispersive soil in this study. Pinhole tests, crumb tests, disintegration tests, particle analysis tests, exchangeable sodium percentage (ESP) tests, pH tests, conductivity tests, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were conducted to explore the modification effects and corresponding mechanisms of RCBP on dispersive soil. The results revealed that the dispersivity of the soil significantly weakened as the RCBP content increased and curing time extended. Specifically, adding 4% RCBP to the soil and curing for 7 days effectively transformed dispersive soil into nondispersive soil. Furthermore, the final disintegration time of the soil sample with 10% RCBP cured for 28 days was 273% longer than that of the soil sample without curing. Moreover, the treatment led to decreased fines content, ESP value, and pH value in the soil samples. The decrease in ESP value indicated the replacement of sodium ions adsorbed on the soil particle surfaces with calcium ions, resulting in a reduction in the thickness of the diffuse electric double layer of soil particles, and subsequently reduced soil dispersivity. Additionally, the decrease in pH also contributed to the reduction of the diffuse electric double-layer thickness. XRD and SEM analyses confirmed the formation of cementing materials between soil particles due to the modification, which filled gaps and cemented particles to create a waterproof barrier between soil particles. In conclusion, the utilization of RCBP as a modifier for dispersive soil could be a win-win measure with promising outcomes. It is recommended that more than 4% RCBP should be added in engineering applications.