双掺陶瓷抛光粉-矿粉对混凝土抗冻性的影响
Effects on frost resistance of concrete mixed with ceramic polishing powder and mineral powder
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摘要: 为研究陶瓷抛光粉与矿粉复合掺合料对混凝土性能的影响,等量替代25%,30%,35%的水泥,其中矿粉掺量为20%,陶瓷抛光粉掺量分别为5%,10%,15%.对混凝土的试验研究分为宏观和微观试验,宏观试验包括抗压强度试验和冻融循环试验,微观试验包括核磁共振(NMR)测试和扫描电镜(SEM)分析.结果表明:养护龄期达到28 d时陶瓷抛光粉-矿粉混凝土的抗压强度优于单掺矿粉混凝土,其中双掺20%矿粉与10%陶瓷抛光粉时,混凝土的抗压强度最高.核磁共振(NMR)测试显示陶瓷抛光粉和矿粉的加入,使得混凝土孔隙半径减小,内部大孔隙向小孔演变,孔隙度降低;在冻融循环后,有害孔数量减少,孔结构得以细化,从而改善了混凝土的孔隙结构,提高了混凝土的抗冻性.SEM图像显示陶瓷抛光粉-矿粉火山灰效应生成C-S-H凝胶,填充在水泥石孔隙中,提高了内部结构致密性,二次水化反应消耗Ca(OH)2,降低了CH晶体的取向性,改善了微观界面黏结强度,提升了混凝土宏观性能.Abstract: In order to study the influence of the compound admixture of ceramic polishing powder and mineral powder on the performance of concrete, the equivalent amount of cement was substituted for 25%, 30% and 35%, in which the mineral powder content was 20%, and the ceramic polishing powder content is 5%, 10% and 15% respectively. The research of concrete was mainly divided into macroscopic tests and microscopic tests.Compression tests and freezing and thawing tests were set up in macroscopic tests. Nuclear magnetic resonance(NMR) and scanning electron microscope(SEM) images analysis were set in microscopic tests. The results shows that the compressive strength of ceramic polishing powder-mineral powder concrete is higher than that of mineral powder concrete when the curing age reaches 28 days. The compressive strength of concrete with 20% mineral powder and 10% ceramic polishing powder is the highest. The NMR shows that the addition of ceramic powder and mineral powder reduces the pore size and porosity of concrete, meanwhile the internal large pores evolve into small pores. After the freeze-thaw cycles, the number of harmful holes reduces and the pore structure is refined, thus ceramic polishing powder improves the pore structure and freeze-thaw resistance of concrete. The SEM images indicate that the ash effect of ceramic powder and mineral powder increases C-S-H gel, fills pores to improve the compactness of concrete internal structure. Meanwhile the se-condary hydration reaction reduces Ca(OH)2(poor orientation crystal)content to enhance the micro-interface bond strength and macroscopic properties of concrete.