Research On Influence Of Different Aggregate Content On Creep Of Recycled Aggregate Thermal Insulation Concrete

Recycled aggregate thermal insulation concrete(RATIC)is a kind of heat preservation and bearing and in the integration of new energy-efficient building materials,but also can realize the secondary utilization of construction waste,it has great market prospect and promotion value.The creep of concrete affects the stress distribution of components and the deformation of reinforced concrete structure,changes the stress state of the structure,and increases the possibility of structural damage,which has a significant impact on Chinese building structure.Therefore,it is necessary to study the influencing factors of creep behavior of the concrete to provide theoretical basis for its further application.In this paper,the recycled coarse aggregate,insulation aggregate(Glazed Hollow Beads)and curing environment as factors affecting research its effect on the properties of RATIC creep rule.The main research contents and conclusions of this paper are as follows:(1)Basic mechanical properties test of concrete.The replacement rate of recycled coarse aggregate is 0,50% and 100%,and the content of insulation aggregate is 0,50% and 100%.The compressive strength test,the compressive strength test of prism and the elastic modulus test are respectively carried out to study the influence of the two kinds of aggregate on the strength and basic mechanical properties of concrete in the long life.The results show that the cubic compressive strength,prismatic compressive strength and elastic modulus of regenerated insulating concrete decrease with the increase of the replacement rate of regenerated coarse aggregate and the content of insulating aggregate,but the regenerated coarse aggregate and insulating aggregate can improve the compressive strength in the long life.(2)Research on influencing factors of creep performance of recycled insulating concrete.Through the creep test of concrete specimens with different replacement rate of recycled coarse aggregate,mixing amount of insulating aggregate and curing environment,the influence law of these influencing factors on concrete creep performance was understood.The results show that concrete creep increases with the replacement rate of recycled coarse aggregate.With the increase of the content of thermal insulation aggregate,the initial strain of concrete increases,but the creep decreases at the later loading stage.Thermal insulation aggregate can improve the resistance of concrete to creep deformation in the long life.Poor curing environment leads to concrete creep.(3)Creep model and long-term compressive strength model of recycled insulating concrete.Through the comparison and analysis of the existing concrete creep prediction model,long-term strength prediction model and test data,and the modification and improvement of the parts which are not suitable for the recycled insulating concrete,the creep prediction model and long-term strength prediction model which can be used for the recycled insulating concrete are obtained.The results show that aci-209 model,CEBFIP(1990)model and B3 model all overestimate the creep of thermal insulation concrete and regenerated thermal insulation concrete,and the corresponding creep influence correction coefficient formula is proposed.The modified model has high prediction accuracy and can be used for the creep prediction of regenerated thermal insulation concrete.The EC2 model is not suitable for the prediction of the compressive strength of regenerated insulating concrete in the long life.Therefore,a modified formula for the influence of insulating aggregate is proposed,and the modified model can be used to obtain a precise prediction model for the compressive strength of regenerated insulating concrete in the long life.