新型早强高性能喷射混凝土胶材的力学性能及微观分析

Experimental Study on the Mechanical Properties and Microstructure Analysis of a Novel Early-Strength High-Performance Shotcrete Colloid

针对目前喷射混凝土普遍存在强度低、耐久性差等问题,通过正交试验确定矿物掺合料用量,在此基础上,进一步研究了粉煤灰、硅灰、复掺硫铝酸盐水泥、无碱速凝剂对胶凝材料力学性能、孔结构和水化产物的影响规律,并揭示了新型混凝土早强高性能的作用机理。结果表明:采用内掺8%硅灰、10%粉煤灰和5%硫铝酸盐水泥,外掺4%无碱速凝剂的配比能够有效降低多害孔的占比,提高无害孔的占比,减少了胶凝体系的总孔隙率,可有效提高胶凝体系抗压强度。硫铝酸盐水泥和无碱速凝剂促进AFt微观骨架的快速形成,硅灰和粉煤灰促进C-S-H凝胶生成,对骨架孔隙进行填充,提高胶材的密实度,优化胶材的孔隙结构,进而提高胶材的力学性能。研究为制备具有早期强度增长速度快和高密实度的新型早强高性能喷射混凝土提供支持。

Currently,shotcrete often encounters challenges such as low strength and poor durability.To address these issues,the optimal amounts of mineral admixtures were determined through orthogonal experiments.Building upon this,the combined effects of fly ash,silica fume,sulfoaluminate cement and the alkali-free accelerator on the mechanical properties,pore structure,and hydration products of the cementitious materials were further examined,revealing the mechanisms driving early high performance.The results indicate that incorporating 8%silica fume,10%fly ash,and 5%sulfoaluminate cement,along with 4%alkali-free accelerator,this system reduces the proportion of harmful pores,increases the proportion of harmless pores,and decreases the total porosity,effectively enhances the compressive strength of the cementitious system.The sulfoaluminate cement and alkali-free accelerator promote the rapid formation of an AFt microstructure,while silica fume and fly ash facilitate the formation of C-S-H gel,filling skeletal pores and enhancing the compactness of the cementitious material.This optimization of pore structure leads to improve mechanical properties,supporting the development of a new type of shotcrete with rapid early strength gain and high density.