Study On Early Deformation Of Iron Ore Tailings Ceramsite Lightweight Concrete And Its Effect On Physical And Mechanical Properties

With the rapid development of prefabricated buildings,the realization of lightweight buildings has become an important aspect of the innovative development of prefabricated buildings.The use of iron tailings ceramsite to prepare lightweight concrete can not only effectively reduce the self-weight of the structure,but also meet the requirements of tailings resource recycling and circular economy,which is of great significance to promoting the development of building assembly and building energy conservation and environmental protection.This paper mainly studied the early shrinkage deformation of ceramsite lightweight concrete and its physical and mechanical properties.Through different methods of ceramsite pretreatment,the early capillary negative pressure and shrinkage deformation of ceramsite concrete and ordinary concrete were compared,and the microstructure and pores of the concrete were studied.On this basis,ceramsite foam concrete was prepared,and its early shrinkage performance and physical and mechanical properties were analyzed and studied.After systematic testing and analysis,the following results have been obtained:The floating of ceramsite in the slurry can be reduced by selecting smaller size ceramsite,reducing the density of the slurry or increasing the yield shear stress and viscosity of the slurry.When using 700 grade iron tailings ceramsite,the proportion of fly ash in the concrete mix is 20%,and when the water-cement ratio is set at 0.35,the ceramsite will not float easily,and the ceramsite concrete matrix will be more uniform.The ceramsite in the 400-grade iron tailings ceramsite foamed concrete is not easy to float,but it needs better maintenance in the early stage.Compared with ordinary concrete,the early reaction of ceramsite concrete is smoother,the capillary negative pressure curve is smoother,the shrinkage is similar to that of ordinary concrete,and the matrix is not easy to crack.The elastic modulus of iron tailings ceramsite concrete is less than that of ordinary concrete,and the lower the compressive strength of iron tailings ceramsite concrete,the greater the difference in elastic modulus from ordinary concrete.Ordinary concrete has a weak interface area with significantly lower hardness,but ceramsite concrete has an interface enhancement area about 60-80μm wide.The ceramsite concrete itself has no obvious interface transition zone.The interface is mainly connected by the friction between the ceramsite and the paste and the occlusal action of the ceramsite surface and the paste.Among the different ceramsite pre-treatment methods,the pre-wet 1h treatment of ceramsite can significantly reduce the possibility of early concrete cracking,and can significantly improve the work performance without significantly increasing the early shrinkage;the saturated ceramsite will increase the possibility of cracking.Early shrinkage and deformation increase the risk of cracking.After adding 50% of the volume of iron tailings ceramsite to the foamed concrete,it can reduce the early shrinkage and deformation and reduce the risk of concrete cracking.Among the foamed concrete with different ceramsite pretreatment methods,the flooded ceramsite group has the lowest risk of early cracking,the matrix exhibits early expansion and deformation,the lowest porosity,and its compressive strength and softening coefficient are the largest,thermal conductivity and water absorption are the lowest.