Modification and mechanism of polymer in high-performance concrete with full aeolian sand: An integrated macro-to-micro perspective

Producing high-performance concrete with full aeolian sand (FA-HPC) can achieve efficient utilization of desert resources to combat the shortage issue of aggregates. However, low water-cement ratio and high fine content result in a high risk of brittleness and durability in this concrete. Herein, polyacrylamide (PAM) and styrene-butadiene rubber latex (SBR) were incorporated into the FA-HPC to optimize its performance. Effects and mechanisms modifying the FA-HPC with polymers were compared and studied from macro-to-micro perspectives, with respect to workability, mechanical properties, durability, adsorption, and hydration. The results revealed a negative correlation with the PAM content (contrary to the SBR content) in fluidity and the content-dependent extension in setting time. For strength and shrinkage, the best performance was observed in the PAM-modified FA-HPC at 0.05% content presenting the substantial mitigation in brittleness. Moreover, regarding chloride resistance, SBR showed a more positive effect than PAM, with a 40.9% improvement at 10% content. From the micro-perspective observation, the retarding effect at early stages and acceleration during the late hydration process were verified by phase analysis. The polymer film and polymer bridge as well as the refined pore structure were the primary contributing factors to the performance improvement. Overall, compared to SBR modification, PAM modification with stronger adsorption capacity balances the comprehensive performance improvement of FA-HPC better at 0.05% content. Additionally, the specificity of the FA-HPC and the difference in modification behavior were discussed. This research allows the material-composition optimization of FA-HPC and further promotes the wide application of aeolian sand-based cementitious materials.