Preparation Of Solid Waste Based Ceramsite And Its Application In Concrete

Coal gangue,fly ash and steel slag as typical solid wastes have caused serious harm to the natural environment.In this paper,using the different chemical properties of gangue,fly ash and steel slag,a more simple and environmentally friendly method is used to prepare solid waste-based lightweight high-strength ceramsite granules with high reuse value and apply them to concrete,which effectively reduces the self-weight of concrete and meets the structural requirements.Through a combination of experimental and theoretical analyses,the raw material ratios as well as the sintering system were determined,and the sintering mechanism of solid waste-based ceramsite pellets was revealed.The physical properties such as crushing strength,water absorption,pore characteristics and density were analyzed,and the evolution of physicochemical properties of ceramsite pellets under different preparation conditions were studied by using XRD and scanning electron microscopy and other testing methods.On the basis of the ceramic pellets produced under the conditions,ceramsite concrete was formulated as aggregates to investigate the effects of different ceramic pellet admixtures on the mechanical properties of concrete,and the microscopic morphology of the interfacial transition zone of ceramsite concrete was analyzed by SEM.Further,the damage mechanism and crack development law of ceramsite concrete were revealed from the fine level by Abaqus finite element simulation software,and the main conclusions are as follows.(1)The reasonable conditions for the preparation of lightweight and high-strength ceramsite pellets using coal gangue,fly ash and steel slag were proposed.When the gangue: fly ash: steel slag for 6:2:2,sintering temperature at 1200 ℃ to prepare the best performance of ceramsite pellets.The test shows that the required sintering temperature of ceramsite pellets and gangue content is positively correlated,in the same sintering temperature,with the increase of gangue content,the water absorption,porosity and crushing strength of ceramsite pellets decreased,the density increased.(2)Revealed the variation of physicochemical properties of solid waste-based ceramsite pellets with the sintering temperature.At the same ratio,as the sintering temperature increases,the crushing strength of ceramic pellets increases and then decreases,the porosity and macropore ratio increases,and the water absorption rate decreases.The mass transfer of ceramsite pellets is more complete,and the internal pores of ceramsite pellets are filled with the generated glass phase,and the generated gas and raw material particles are wrapped,making the ceramsite pellets more dense.(3)Through reasonable proportional design of vitrified concrete,the vitrified concrete with 50% and 100% vitrified grains replacing crushed stone by equal volume can meet the strength grade of LC35 and meet the density requirements of the specification for light aggregate concrete.(4)By simulating the two-dimensional 150mm*150mm members of vitrified concrete,it was found that the compressive damage of vitrified concrete starts with cracks at the interface transition zone,and then the cracks penetrate the vitrified concrete and extend further until the vitrified concrete reaches the ultimate load strength;by numerically simulating the splitting tensile strength of vitrified concrete,the end cracks of vitrified concrete partly penetrate the aggregate and partly develop along the interface region between the aggregate and the mortar.