Strength And Micro-mechanism Of Red Mud-mswi Fly Ash-carbide Slag-fly Ash Composite

Red mud and carbide slag are solid wastes discharged from industrial production,which have strong alkalinity and can easily affect the surrounding ecological environment if accumulated for a long time.Fly ash is dust particles collected during waste incineration power generation.The content of heavy metals in waste incineration fly ash is high,and long-term accumulation can cause pollution to the surrounding soil.How to scale and quantify the consumption of solid waste has become the focus of scholars at home and abroad.In this paper,on the basis of the original red mud carbide slag fly ash ternary cementitious system,adding waste incineration fly ash to form a red mud carbide slag fly ash quaternary cementitious system,molding the test piece by pressing.Based on the macroscopic strength of the pressed specimens made of quaternary cementitious materials,the optimal amount of fly ash was selected and the optimal ratio was determined.By changing the high temperature curing temperature and curing time of pressing molding,the effects of different curing methods on the macroscopic mechanical properties of the quaternary cementitious system were investigated.The results show that when the mass ratio of red mud to fly ash to calcium carbide slag to fly ash is 3:2:2:3,the water cement ratio is 0.3,and the sand cement ratio is 3,and the curing temperature is 60 °C for 8 h,the compressive strength of the pressed specimens of the quaternary cementitious material at 7d and 28 d can reach 13.4 MPa and 17.6 MPa.The 28 d heavy metal leaching test was carried out on the optimal proportion of test pieces,and the test results showed that the pressed test pieces had a good solidification effect on heavy metals,and all heavy metal leaching concentration indicators met the standard requirements.XRD and SEM-EDS tests were carried out on 28 d old slurry samples.The microscopic test results showed that the main crystal components in the system were Ca CO3,Na Cl,3Ca O · Al2O3 · Ca Cl2 · 10H2 O and Fe2O3.The microscopic morphology of the 28 d quaternary gelling system was observed.There were a large number of square sheet shaped crystals and amorphous gelling products in the system.Needle shaped,crystalline substances and amorphous hydration products were filled and overlapped with each other to form a unified whole,providing strength for the system.The development and research of a four component solid waste cementitious system can provide a theoretical reference for the metrological and large-scale utilization of red mud,fly ash,carbide slag,and fly ash,with certain social and environmental benefits.