Preparation process and performance study of desert sand autoclaved bricks

Abstract

Desert Sand Autoclaved Brick(DSAB) represents a novel type of building wall material. To investigate the performance of this wall material in the high-intensity cold regions of Xinjiang, this study, based on the(GB/T 11945–2019) ''Autoclaved sand-lime solid brick and solid block'' standard, explores the impact of varying lime content, forming pressure, autoclaving time, and autoclaving temperature on compressive strength. The aim was to determine an appropriate preparation process for DSAB that meets meets MU15-grade requirements. Additionally, experimental research was conducted on the micro-pore structure, freeze-thaw durability, and carbonation performance of the manufactured MU15-grade DSAB. Furthermore, microscopic analysis methods were employed to analyze the mechanisms behind the changes in the strength of the DSAB throughout the various experiments. The research findings are as follows: The optimal preparation parameters for producing MU15-grade DSAB are a forming pressure of 20 MPa, an autoclaving time of 8 h, and an autoclaving temperature of 180 ℃. Mercury intrusion porosimetry(MIP) revealed that DSAB has a total porosity of 38.19%, an average pore diameter of 55.86 nm, total pore volume of 0.175 mL/g, and total pore area of 12.56 m2/g. The majority of pore spaces consist of harmful and more harmful pores. DSAB exhibits favorable freeze-thaw durability. After 30 freeze-thaw cycles, the strength loss rate is only 7.0%, and the mass loss remains within 1%. After carbonation, the newly formed CaCO3 and SiO2 fill the brick's pores, transforming pre-existing harmful large pores into harmless tiny pores. After complete carbonation, the carbonation coefficient reaches 1.17.

Keywords

• Desert sand
• Autoclaved bricks
• Strength
• Durability