复合外加剂对充填浆体固化前后性能的影响规律

Influence law of compound admixture on the mechanical properties of filling slurry before and after curing

为了提高煤矿充填浆体固化前后的性能,利用硫酸钠和聚羧酸减水剂复掺制备成复合外加剂,通过宏观实验探究其对充填浆体固化前后工作性能和力学性能的影响,并结合微观实验分析其影响机制。实验表明,0.5wt%硫酸钠与0.2wt%聚羧酸减水剂复掺的充填浆体,其水泥用量可减少2%,塌落度可增加4.1 cm,初凝时间和终凝时间可缩短20 min,减水率可提高7.7%,3天和28天单轴抗压强度最高可增加22%和42%。分析表明,硫酸钠的早强机制、聚羧酸减水剂的静电斥力作用和空间位阻作用及二者的互促作用是影响充填浆体固化前工作性能的主要原因,而针状性产物钙矾石和白色纤维状物质水化硅酸钙是影响充填浆体固化后力学性能的主要物质,二者的生成提高了充填膏体的单轴抗压强度。

In order to improve the performance of coal mine filling slurry before and after solidification,sodium sulfate and polycarboxylic acid water reducing agent were used to prepare a composite admixture,and the effect on the working performance and mechanical properties of the filling slurry before and after solidification was explored through indoor macroscopic experiments.Its influence mechanism was analyzed in combination with indoor microscopic experiments.Experiments show that the cement consumption of 0.5wt%sodium sulfate and 0.2wt%polycarboxylic acid water-reducing agent mixed filling slurry can be reduced by 2%,the slump can be increased by 4.1 cm,the initial and final setting time can be shortened by 20 min,and the water reduction rate can be increased by 7.7%,the 3rd day and 28th day uniaxial compressive strength can increase up to 22%and 42%.The analysis shows that the early strength mechanism of sodium sulfate,the electrostatic repulsion and steric hindrance of polycarboxylic acid water-reducing agent,and the mutual promotion of the two are the main reasons that affect the working performance of the filling slurry before curing.The needle-like product ettringite and the white fibrous substance calcium silicate hydrate are the main substances that affect the mechanical properties of the filling paste after solidification,and the formation of the two improves the uniaxial compressive strength of the filling paste.