金尾矿砂制备水泥注浆料的流变性能及力学性能研究

Study on Rheological Properties and Mechanical Properties of Cement Grouting Material Prepared by Gold Tailing Sand

针对地下空间堵漏注浆料成本高、体积不稳定等问题,以细度模数低于0.7的金尾矿砂制备流变性能优异的水泥注浆料,提升注浆料性能的同时实现固废资源化利用。对金尾矿砂的颗粒分布、化学成分、矿物组成以及颗粒形貌进行了测定,通过单因素试验系统研究了外加剂掺量及水胶比对金尾矿砂水泥注浆料流变性能以及力学性能的影响,结合SEM分析方法揭示了水胶比对力学性能的影响规律。结果表明:以石英为主要矿物的微细金尾矿砂颗粒细、棱角多,通过外加剂进行表面改性,固定胶砂比为1∶1.5,控制水胶比为0.35,注浆料流动度最高可达335 mm;控制水胶比为0.31,注浆料抗折强度达到最高,3、7、28 d抗折强度分别为6.87、8.87以及10.5 MPa;控制水胶比为0.32,注浆料抗压强度达到最大,3、7、28 d抗压强度分别为43.1、59.0以及69.0 MPa;金尾矿砂水泥注浆料脆性系数随水胶比增高而降低,试样28 d脆性系数最低为5.58。通过SEM分析发现随着水胶比增加,钙矾石(Aft)相增多,脆性系数减小,韧性提高,但Aft相过多导致结构松散,强度降低。

The cement grouting material with excellent rheological properties was prepared by gold tailing sand with a fineness modulus lower than 0.7 to improve the performance of the grouting material and to realize the resource utilization of solid waste in response to the problems of high cost and unstable volume of underground space plugging grout.The particle distribution,chemical composition,mineral composition and particle morphology of gold tailing sand were determined,and the effects of additive admixture and water-binder ratio on the rheological properties and mechanical properties of gold tailing sand cement grouting material were investigated systematically by single-factor test,and the influence of water-binder ratio on mechanical properties was revealed by SEM analysis.The results showed that the fine-grained and angular gold tailing sand with quartz as the main mineral,and the flow degree of cement grouting material can reach up to 335 mm when the surface of the tailing sand is modified by admixture,the fixed cement sand ratio is 1∶1.5 and the control water-binder ratio is 0.35.The maximum flexural strength of the cement grouting material was reached at a controlled water-binder ratio of 0.31,with flexural strengths of 6.87,8.87 and 10.5 MPa at 3,7 and 28 d,respectively,and the compressive strength of the cement grouting material reached the maximum at a water-binder ratio of 0.32,with compressive strengths of 43.1,59.0,and 69.0 MPa at 3,7 and 28 d,respectively;The brittleness coefficient of gold tailing sand cement grouting material decreases with the increase of waterbinder ratio,and the lowest 28 d brittleness coefficient is 5.58.The SEM analysis showed that with the increase of water-binder ratio,the calcium alumina(Aft)phase increases,the brittleness coefficient decreases and the toughness increases,but too much Aft phase led to the loosening of the structure and the decrease of strength.