掺早强剂改性赤泥-水泥膏体复合材料性能研究

Study on properties of red mud-cement paste composites modified with early strength agent

为实现赤泥等大宗固废的资源化利用,解决某金矿充填料浆凝结时间长、充填体质量差、早期强度低的应用瓶颈,以甲酸钙作为外加剂改良赤泥胶凝材料凝结硬化性能。首先,开展原材料基本物理化学性质研究;然后,设计不同掺量甲酸钙影响料浆塌落度、扩展度、稠度、分层度、凝结时间和抗压强度的试验;最后,通过扫描电镜探讨复合材料水化产物的类型及水化机理。研究结果表明:随着甲酸钙掺量的增加,料浆凝结性能表现为“增稠促凝”,且掺量越大,增益效果越显著,但仍能保证料浆管道正常输送;甲酸钙掺量从0%增加至3%的过程中,充填体抗压强度均呈先上升后降低的趋势,当甲酸钙掺量为1.5%时,7 d和28 d抗压强度最大,当甲酸钙掺量为2%时,3 d抗压强度最大。在甲酸钙的调控作用下,HCOO^(-)渗透至硅酸三钙和硅酸二钙的水化膜层,缩短水泥水化诱导期,提高水化反应速率,生成更多发育良好的短棒状钙矾石和团聚状C-S-H凝胶,充填体结构致密度和结晶度更高,宏观强度随之增大。

In order to realize the resource utilization of bulk solid waste such as red mud and address the application bottleneck of long setting time,poor quality of filling body and low early strength of a gold mine filling slurry,calcium formate was used as an admixture to improve the setting and hardening performance of red mud cementing material.Firstly,the basic physicochemical properties of raw materials were studied;then,tests were designed to investigate the effects of different doses of calcium formate on the collapse,expansion,consistency,delamination,setting time and compressive strength of the filling slurry;finally,the types of hydration products and the hydration mechanism of the composite filling materials were investigated by scanning electron microscopy.The research results show that with the increase of calcium formate dosing,the coagulation performance of the filling slurry is"thickening and promoting coagulation",and the greater the dosing,the more significant the gain effect,but the normal transportation of the slurry pipeline can still be ensured;the compressive strength of the filling body shows a trend of rising first and then decreasing during the increase of calcium formate dosing from 0%to 3%,and the compressive strength at 7 d and 28 d was the highest when calcium formate was mixed with 1.5%,and the compressive strength at 3 d was the highest when calcium formate was mixed with 2%.Under the control of calcium formate,HCOO^(-)penetrated into the hydration film layer of tricalcium silicate and dicalcium silicate,which shortened the hydration induction period of cement,increased the hydration reaction rate,produced more well-developed short rod-like calcium alumina and agglomerated C-S-H gel,and increased the density and crystallinity of the filling body structure,and then increased the macroscopic strength.