Study On Mechanical Properties And Photocatalytic Efficiency Of Recycled Lightweight Decorative Concrete

Recycled concrete is a kind of environmental protection building material,which has the characteristics of sustainable development,and sustainable development has become the focus of the world.With the industrialization of the city and the change of the old and new buildings,people’s vigorous development of the earth’s storage resources will consume a lot of earth’s resources,produce a lot of construction waste,and then destroy the ecological balance of the whole environment.This paper mainly studies the physical and mechanical properties of recycled lightweight decorative concrete,and the photocatalytic degradation rate of formaldehyde after adding photocatalyst into concrete.In this paper,ceramsite aggregate is replaced by recycled lightweight aggregate with 0,25%,50% and 75% of total mass under different water cement ratio.The physical and mechanical properties of concrete products made in 7 and 28 days were tested,and the influence of recycled lightweight aggregate on recycled lightweight decorative concrete was analyzed.Through the experiment and research in this paper,the change rule of physical and mechanical properties of recycled lightweight decorative concrete with different replacement rate of recycled lightweight aggregate is observed.The results show that:(1)Comparing recycled lightweight aggregate with natural aggregate,it is found that the main characteristics of recycled lightweight aggregate are high apparent density,high water absorption and low compressive strength.The aggregate ratio of crushed ceramsite concrete is 63.34%,which is much higher than that of ordinary concrete.(2)TThe properties of aggregate are very important for the physical and mechanical properties of concrete samples.When the water cement ratio increases,the compressive strength of recycled lightweight decorative concrete decreases rapidly.The strength of recycled lightweight decorative concrete is inversely proportional to the increase of water cement ratio.When the water cement ratio is 0.38,its strength is the highest;However,when the water cement ratio is small,the replacement rate of recycled aggregate is the most important factor affecting the compressive strength of recycled concrete.When the water cement ratio is large,the substitution rate has little effect on its compressive strength.The results show that the replacement rate of recycled aggregate and the water cement ratio in recycled lightweight decorative concrete have a great influence on the compressive strength of recycled lightweight decorative concrete.(3)With the increase of water cement ratio,the splitting tensile strength of recycled lightweight decorative concrete decreases.When the replacement rate of recycled lightweight aggregate is 25%,its splitting tensile strength can reach more than 90% of the compressive strength of concrete without recycled lightweight aggregate,so 25% of the replacement rate of recycled lightweight aggregate is more appropriate.(4)Through the finite element analysis of ANSYS,the simulation analysis of recycled lightweight decorative concrete is carried out.The results show that the thickness of mortar attached to the surface of recycled lightweight aggregate and its physical and mechanical properties have a great impact on the compressive strength of recycled lightweight concrete.The more the replacement rate of recycled aggregate,the more unfavorable the compressive strength of recycled lightweight concrete.(5)In the photocatalytic experiment,when the content of titanium dioxide in the recycled lightweight decorative concrete increases,the photocatalytic degradation rate of the sample increases,and the surface spraying method is more efficient than the internal mixing method in removing formaldehyde.The increase of UV intensity is positively related to the degradation efficiency of formaldehyde.The main influence on the photocatalytic efficiency is that in the concrete sample,the photocatalyst can receive the specific surface area of the light source.