Study On Physical And Mechanical Properties Of Wheat Straw Fiber Porous Ceramsite Concrete

With the acceleration of China's urbanization process,more and more impervious roads and buildings hinder the need for water and air permeability of the environment,which has caused serious negative impact on the ecological environment for aggravating the urban heat island effect and rainwater runoff.The construction of sponge city is an important way to realize the coordinated development between city and nature.Porous concrete can connect the upper and lower ecological environment because of a large number of connected pores,so it is an indispensable material for sponge city construction.On the other hand,China is rich in straw resources,but sand and gravel are increasingly in short supply.Therefore,the rational use of straw and ceramsite as coarse aggregate meets the requirements of recycling economy,environmental protection and ecological construction.In this paper a new type of porous concrete is developed using wheat straw fiber and ceramsite according to a lot of experiments,and its physical and mechanical properties are tested experimentally.The main contents and conclusions are as follows.(1)Pretreatment of test materials.The ceramsite is processed into a saturated surface,and the wheat straw fiber is cut short,soaked in 4%NaOH solution,dried after washed.(2)Research on mix design and forming method of test specimen.According to the filling theory,the mix ratio of wheat straw fiber porous ceramsite concrete is determined with the target porosity as the design index.In addition,the test specimen is molded by shaking on a vibrating table for 30s.(3)Experimental study on physical and mechanical properties of wheat straw fiber porous ceramsite concrete.When the water cement ratio is 0.30,the straw fiber contents are 0,2%,4%,and 6%,the target porosities are 5%,10%,15%,20%,and 25%,and the sizes of ceramisite are 5-10mm and 10-20mm,the28d compressive strength,dry density,measured porosity and thermal conductivity under dry and saturated conditions of porous concrete are measured.The 28d compressive strength of porous concrete prepared by1#ceramics ranges from 0.595MPa to 3.579MPa,the dry density ranges from 613kg/m~3 to 886kg/m~3,and the measured porosity ranges from 36.5%to 52.4%.Compared with above,the porous concrete prepared by 2#ceramsite has a greater 28d compressive strength but a less dry density or measured porosity.Whether it is dry or saturated,its thermal conductivity is less than that of porous concrete prepared by 1#ceramsite,and the minimum thermal conductivity is 0.4182 W/(m·K).(4)Application research of wheat straw fiber porous ceramsite concrete.Based on the physical and mechanical properties of porous concrete,the new types of inverted roof and ventilated roof structure are designed.