Experimental Study and Analysis of the Effects of Mud on the Compressive Strength of Unburned Brick Using Engineering Residue Soil

Engineering residue soil, a prominent type of construction solid waste, can offer considerable environmental and socioeconomic benefits if efficiently utilized. Unburned brick represents an environmentally friendly and high-value approach to reusing this residue soil. Mud, a primary constituent of residue soil, typically hinders the performance of unburned brick using cement-based materials. This study investigates the effects of mud on the performance of unburned brick made from engineering residue soil based on experimental tests and mechanism analysis. The residue soil is silty clay sourced from the alluvial soil layer in South China. A comprehensive analysis of the physical and chemical properties of the residue soil and mud is conducted to assess the feasibility of using them in unburned brick production. Using ordinary Portland cement as the cementitious material, the unburned residue soil bricks are produced via semi-dry static-press forming and natural curing. The influence of mud type and content on the compressive strength of the unburned brick made with engineering residue soil is investigated and discussed. This experimental study reveals that the influence of mud on unburned brick’s compressive strength is negligible. However, excessively low mud content reduces brick compactness, impairs brick formation, and leads to lower compressive strength. Within the range of solidification, unburned brick’s compressive strength initially increases and then decreases with increasing mud content, with an optimal mud content of approximately 25%. As engineering residue soil often contains a high mud content, reducing it effectively enhances the compressive strength of unburned bricks. Through experiments and mechanism analysis, this research clarifies the impact of mud on the strength and performance of unburned residue soil bricks, providing important theoretical insights and practical guidance for the production of unburned products and promoting the efficient and environmentally friendly resource utilization of engineering residue soil.