聚合铝对锂渣-水泥复合胶凝材料水化硬化特性的影响

Effect of polymeric aluminum on hydration hardening characteristics of lithium slag-cement composite cementitious materials

锂渣具有火山灰活性,可作为辅助性胶凝材料应用于水泥基材料中,但其较低的水化活性导致材料的力学性能和耐久性能下降。针对锂渣在复合胶凝材料中的低水化程度,本文采用一种无机高分子聚合铝作为激发剂来提升锂渣的水化反应活性,通过测定材料的胶砂强度、化学结合水量等宏观性能,并结合水化放热特性、水化产物矿物组成及背散射显微形貌等微观表征,分析了聚合铝对锂渣-水泥复合胶凝材料水化特性的影响及作用机理。结果表明:聚合铝的掺入显著提高锂渣-水泥复合胶凝材料28 d龄期的抗压强度和化学结合水含量,分别增长了26. 8%和5%;早期水化反应中,聚合铝的掺入加速了锂渣-水泥复合胶凝体系的矿物相溶解和晶体的生长,增加了水化产物的成核总量,水化产物中出现了大量的钙矾石、水化铝酸钙、氢氧化钙及非晶态水化凝胶;聚合铝的掺入促进了锂渣-水泥复合胶凝体系的水化和锂渣颗粒的溶解与侵蚀。

Lithium slag is used as a supplementary cementitious material in cement-based materials due to its pozzolanic activity,but its lower hydration activity leads to a decline in the mechanical properties and durability of the cement-based material.In this paper,for the low degree of hydration of lithium slag in composite cementitious materials,an inorganic polymer aluminum was used as an activator to improve the hydration activity of lithium slag.The effects and mechanism of polymeric aluminum on hydration hardening of lithium slag-cement composite cementitious materials were investigated through macro properties of compressive strength and non-evaporable water content,and micro characteristics of hydration heat,mineral composition of hydration products and BSE microscopic morphology.The results indicate that the addition of polymeric aluminum significantly improves the compressive strength and non-e-vaporable water content in the lithium slag-cement composite cementitious material,which increases26.8%and 5%respectively in the 28 d period.In the early hydration,polymeric aluminum accelerates the mineral phase dissolution and crystal growth in the lithium slag-cement composite cementitious material,and increases the total nucleation of hydration products.A large number of ettringite,hydration calcium aluminates,calcium hydroxide and amorphous hydration gels appeare in the hydration products,which promote hydration of lithium slag-cement composite cementitious system,the dissolution and erosion of lithium slag particles.