角闪岩弃碴机制砂和石粉掺量对混凝土性能的影响机理

Influence Mechanism of Hornblende Ballast Machanical Sand and Stone Powder Content on Properties of Concrete

为探明角闪岩弃碴制砂过程中石粉对混凝土性能的影响,以冀环京津6个地区的角闪岩弃碴为对象,通过开展力学测试、坍落度试验和Zeta电位分析,并结合SEM、FTIR等测试探讨了角闪岩弃碴机制砂和石粉掺量对混凝土工作性能、力学性能及微观结构的影响机理。研究表明:除鑫鑫地区外,其他地区的角闪岩弃碴机制砂均可提升混凝土的抗压强度,其中承德和小石匣地区的角闪岩弃碴机制砂对混凝土增强效果较优,与天然砂制备的混凝土相比,这两种弃碴机制砂制备的C30混凝土7 d抗压强度分别提升了20.51%和11.11%,28 d抗压强度分别提升了10.79%和6.58%;C50混凝土7 d抗压强度分别提升了15.14%和12.57%,28 d抗压强度分别提升了14.55%和16.55%。承德、鑫鑫、冀恒和小石匣地区石粉最佳掺量一般可达胶凝材料质量的8%~15%,而平山地区最佳掺量仅为5%。其中承德和小石匣地区石粉取代胶凝材料用量最高,原因在于这两个地区石粉的颗粒粒度较小,SEM表明在碱性条件下石粉呈明显侵蚀破坏形貌,在骨料界面处形成较多胶凝产物,提升了骨料颗粒之间的胶结程度。此外,适量石粉的加入对丰宁地区较粗机制砂混凝土有一定填充作用,能提升混凝土力学性能。FTIR和Zeta电位测试结果表明,角闪岩弃碴石粉能吸附聚羧酸减水剂并发生反应生成离子化合物,聚羧酸减水剂提升了石粉、水泥和聚羧酸溶液体系稳定性。本研究可为角闪岩弃碴机制砂在普通混凝土中应用及石粉在混凝土中取代不同胶凝材料用量配比设计提供参考。

In order to clarify the influence of stone powder on the performance of concrete in the process of sand making by hornblenede ballast waste slag,the hornblende ballast waste slags from six areas in Hebei province surrounding Beijing and Tianjin Region were taken as experimental materials.The influence mechanism of hornblende ballast mechanical sand and stone powder content on the workability,mechanical properties and microstructure of concrete were investigated by mechanical tests,slump test,zata potential test,SEM and FTIR.The results indicate that except for Xinxin in the six regions,hornblende ballast mechanical sand can enhance compressive strength in all other regions.Wherein,Chengde and Xiaoshixia regions have the superior strengthening effect on concrete.Compared with concrete prepared by natural sand,after curing of 7 d,the compressive strength of C30 concrete prepared by Chengde and Xiaoshixia aggregate increases by 20.51%and 11.11%,and after curing of 28 d,the compressive strength increases by 10.79% and 6.58%,respectively.For C50 concrete,the compressive strength increases by 15.14% and 12.57% after curing 7 d,and increases by 14.55% and 16.55%after curing of 28 d,respectively.The optimal stone powder content of Chengde,Xinxin,Jiheng and Xiaoshixia is 8%~15% of cementitious material,but only about 5%for stone powder of Pingshan.Among,the stone powder content replacing cementitious materials in Chengde and Xiaoshixia regions is the highest.The reason is that the particle size of stone powder in these two areas is small.SEM shows that the stone powder shows obvious erosion and damage morphology under alkaline conditions,and more cementitious products are formed at the aggregate interface,which improves the degree of cementation between aggregate particles.In addition,the appropriate of stone powder content has a certain filling effect on the coarser manufactured sand concrete in Fengning area,which can improve the mechanical properties of concrete.The results of FTIR and Zeta potential tests show that the hornblende ballast waste slag rock powder can adsorb the polycarboxylate superplasticizer and react to form ionic compounds.The polycarboxylate superplasticizer improves the stability of the stone powder,cement and polycarboxylate solution system.This study can provide a reference for the application of hornblende ballast mechanical sand in ordinary concrete and the proportion design of stone powder replacing different cementitious materials in concrete.