Research Of Modified Straw Cement-basedmaterials

The addition of fiber can make cement-based composite materials have more functions and USES,used in cement-based composite materials such as low carbon steel fiber,stainless steel fiber,glass fiber,carbon fiber,polypropylene fiber,nylon fiber,natural plant fiber,etc.And the improving of the green environmental protection consciousness to make domestic and foreign experts pay more and more attention to the study of plant fiber cement-based composite materials,although the plant fiber composite material has the advantage of light quality,production,renewable,etc many advantages,but there is no plant fiber and cement materials very good bonding effect,thus reducing mechanics and durability of the composite cement base material [1];In addition,plant fiber types,growth areas,growth cycles,as well as different pretreatment technology,length,dosage,may lead to plant fiber cement-based composite properties change.At home and abroad,the research on the physical properties,mechanical properties and durability of straw straw is relatively partial.This paper mainly focuses on the comprehensive study of straw straw fibers,waste crops in hubei province.The quality loss and mechanical properties of straw straw fibers are caused by different concentrations of alkali solution and different soaking time,and the optimal alkali solution concentration and soaking time are obtained.1.Straw straw was immersed in different concentrations of alkali solution and soaked for different time to determine the weight loss rate of straw straw after soaking,so as to characterize the precipitation rate of delayed or anticoagulant components in straw straw fibers.In order to prevent the alkali aggregate reaction caused by the degradation of cellulose molecules by excessively high concentration of alkali solution,excessively long soaking time and excessively high alkali concentration,which is the key to enhance the mechanical properties of composite materials,the alkali solution with a concentration of4% was selected for the test and the soaking time was 12 hours.Through the macro and micro analysis of straw,it is verified that the surface of straw after pretreatment has gully,which is more conducive to the interface combination with cement-based material.Sample determined by base mixture ratio of compressive strength and flexural strength,the experimental results indicate that adding alkali solution treated than untreated straw,straw fiber mechanical properties improved significantly.2.Using L9(33)orthogonal table,the water cement ratio,dosage of straw stalk,rice straw stalk length as three influence factors,each factor to select three level,water cement ratio 0.5,0.6,0.7 respectively,the straw stalk length respectively,10 mm,15 mm,5 mm straw content respectively accounts for 2%,4%,6% of cement quality,through the nine pairs of trials were flexural strength and compressive strength test,calculate the compression ratio,and carries on the analysis,to analyze the relations between the factors and test index,probe into the impact of various factors on mechanical properties of composite materials,primary and secondary order optimal experiment scheme.The test results showed that straw content had the greatest influence on the composite material,and the optimum straw length was determined to be 10 mm and the water-cement ratio was0.6.3.To explore the effects of straw content on the physical and mechanical properties of composite materials,the straw content was taken as 2%,4%,6%,8%,10%,12%,14%,and 16%,and the blank test group was added to determine the flexural strength and compressive strength of 7 days and 28 days respectively,as well as the flexural ratio of each test group at different periods.The test results showed that when the straw content was 6%,the flexural strength and flexural ratio of composite materials were the best.T0,T3,T4,T5,T6,the experimental group to determine the physical properties,including setting time,water retention and coefficient of thermal conductivity test,the test results show that the modified with straw had no significant effect on the setting time,the blank group of initial setting time,shortest dosage was 10% final setting time the shortest,the optimal dosage of 10% water retention performance,thermal performance is optimal,12%when the optimal thermal performance.4.Test groups T0,T3,T4,T5 and T6 were selected for durability determination,which mainly included impermeability,frost resistance and sulfate resistance.The results showed that the best impermeability was obtained when the content was 8%,and the best sulfate resistance and frost resistance were obtained when the content was 10%.