Experimental Study On Mechanical Properties Of Concrete With Iron Tailings After High Temperature

Iron tailing sand is the by-product of iron ore mining and one of the most important industrial wastes in China.Due to the lack of effective utilization,there are tens of billions of tons of tailings in the tailings pond.The massive discharge of tailings sand not only causes serious pollution to the natural environment,but also poses a serious threat to the safety of people's life and property.In recent years,many scholars and institutions have conducted a series of researches on the performance of concrete made from iron tailings.At present,remarkable achievements have been made in SCC,ECC,UHPC and other directions,but we have neglected that there are still some defects in the actual large-scale application of iron tailing caused by its complex composition,it may even cause security risks.Therefore,this topic starts with the characteristics of instability at high temperature of iron tailings sands,focusing on the mechanical properties of iron tailings sands after high temperature and the calculation method of concrete residual carrying capacity after high temperature.The main research contents are as follows:1.Firstly,the main components of iron tailings were analyzed by SEM-EDS,XRD,XRF,TGA-DSC technology,and the engineering properties of iron tailings sand were evaluated according to the requirements of Construction Sand.Then,through the experiments of six groups of concrete prismatic body axial compression,this paper compares the influence of iron tailings sand,mixed sand(50%),and river sand on the compressive strength,elastic modulus,peak strain and stress-strain curve of high-strength concrete and ordinary concrete.2.Based on the axial compression test at room temperature,36 groups of prismatic specimens were tested under six high-temperature conditions(100 ? 600 ?).Through obtaining the stress-strain relationship of concrete after high temperature,this paper analyzes the influence of iron tailings sand,mixed sand and river sand on the mechanical properties of high-strength concrete and ordinary concrete after high temperatures,such as compressive strength,elastic modulus,peak strain,and stress-strain curve,and fitting the functional relationship of mechanical properties of concrete with temperature according to the experimental data.3.Based on Abaqus software,three key problems in the nonlinear calculation of concrete structures after the fire are solved:(1)how to select the concrete thermal model and boundary conditions,(2)how to extract the maximum node temperature field of concrete structure in the process of heating or cooling,and(3)how to calculate constitutive parameters of concrete after high temperature.Based on the numerical simulation results of a group of river sand concrete beams before and after the fire,this paper predicts the bearing capacity of iron tailing concrete beams after firing for 1h,2h,and 3h,and compares the mechanical properties of iron tailing concrete beam members and river sand concrete beams after the fire.