Research On Properties And Thermal Insulation Mechanism Of Shale Ceramsite Foam Concrete

The shale ceramsite foam concrete was a kind of new energy-efficient building materials,which had excellent performance,such as recycling,environmental protection,energy saving,cheap and incombustible.The shale ceramsite foam concrete was a new lightweight thermal insulation material,which was made of cementing material(cement,fly ash),aggregate(ceramsite,ceramic sand),and the foam agent.The concrete contained a lot of closed porosity after curing.In this paper,The shale ceramsite foam concrete was prepared with different foam volume,water-binder ratio(0.35,0.35,0.4,0.5,0.55,0.6,0.65),fly ash mixing quantity(10%,15%,20%,25%,30%,40%,45%)as variables.And the relation of variables with compressive strength and water absorption at 28 d had been studied too.Meanwhile,this paper set up the mathematical relationship between variables and performance.On the basis of preliminary test,we prepared blocks with the optimal mixture ratio,and also researched their properties such as compressive strength,water absorption,frost resistance,drying shrinkage.Based on the physical foaming,we prepared shale ceramisite foam concrete with different levels of density,and tested their porosity and thermal conductivity,and also established the mathematical relationship.In addition,we studied the porosity distribution by spiral CT technique and scanning electron microscope(SEM)method,analyzed the mechanism of thermal insulation,established the mathematical model for predicting thermal conductivity.On the basis of laboratory tests,this paper researched the construction technology of the shale ceramsite foam concrete,studied the shale ceramsite foam concrete properties through field sampling,such as compressive strength,bibulous rate,thermal performance of simulation of the wall.Results show that:(1)As the foam increased,dry density,compressive strength gradually decreased,and water absorption increased.(2)With the increasing of the water-binder ratio,the 28 d compressive strength decreased,but the water absorption increased.(3)Concrete strength increased at first and then decreased with the increasing dosage of fly ash,but water absorption basically remain unchanged.(4)The mass loss and strength loss of the shale ceramsite foamed concrete prepared by the experiment were 1.82% and 5.4% respectively,and the drying shrinkage was small.(5)The thermal conductivity of the shale ceramic foam was small and was closely related to the porosity of the concrete.The higher the porosity was,the smaller the thermal conductivity was.The shale ceramsite foam concrete were found to contain large amounts of porosity by spiral CT technique and scanning electron microscope(SEM)method,the porosity and the pores inside the shale ceramsite greatly reduced the thermal conductivity of concrete,so the shale ceramsite foam concrete had excellent insulation properties.(6)Based on the series and parallel thermal resistance network model,the mathematical model of equivalent thermal conductivity and porosity of ceramic foamed concrete was deduced.Through the comparison between the measured values and the theoretical values of the two thermal conductivity mathematical models,it was found that the theoretical and measured values of the two mathematical models were less sensitive and had good adaptability.(7)The compressive strength of the shale ceramisite foam concrete samples was 15.21 MPa and the water absorption was 5.49%.The thermal performance of simulated the shale ceramisite foam concrete wall was 1.040 K /(W /(m2·K)).