Experimental Study On Mechanical Properties And Durability Of Metakaolin Rubber Concrete

Adding waste rubber into concrete can not only effectively improve many properties of concrete,such as frost resistance,crack resistance,impact resistance,impermeability,noise reduction and sound insulation,but also benefit the sustainable development of ecological environment.Metakaolin is a kind of mineral admixture with super pozzolanic effect.A large number of studies show that metakaolin can partly replace the cement in the concrete production process,which can not only reduce the amount of cement,play the benefits of energy saving and emission reduction,but also enhance the mechanical properties and frost cracking resistance of concrete.In this paper,the compressive strength,splitting tensile strength,freeze-thaw cycle test,early cracking resistance test and scanning electron microscope test of concrete blocks with different rubber and metakaolin content were carried out,the specific contents are as follows:(1)Rubber is used to replace the fine aggregate in concrete with equal volume,and the content is 0%,10%,13%,16%and 19%respectively;metakaolin is used to replace the cement in concrete,and the content is 0%,10%,13%,16%and 19%respectively.The 28d compressive strength and 28d splitting tensile strength of concrete blocks with different rubber and metakaolin contents are obtained through the compressive and splitting tensile strength tests.The test data are analyzed from different angles to analyze the influence of rubber and metakaolin on the 28d compressive and splitting tensile strength of concrete blocks.(2)In order to explore the frost resistance of concrete mixed with rubber and metakaolin,the freeze-thaw cycle test was carried out on the concrete blocks with different contents.The slow freezing method is used in the test.The mass loss rate and ultrasonic speed of the experimental group are detected when the concrete blocks are frozen and thawed for 25 times,50 times,75 times and 100 times.After 100 times of freeze-thaw cycle,the compressive strength test of each test block is carried out to obtain the strength loss rate of the test block.From the above three aspects,the strengthening degree of rubber and metakaolin on the frost resistance of concrete blocks is analyzed.(3)Combined with the 28d compressive strength,28d splitting tensile strength and freeze-thaw cycle test data of each group of concrete blocks,the early crack resistance performance of metakaolin rubber concrete,rubber concrete and benchmark concrete with the most representative ratio were tested,and the early crack data were obtained,and they were divided according to the crack resistance grade.(4)Through the scanning electron microscope(SEM)test on the concrete block with 10%rubber and the concrete block with 10%rubber and 13%metakaolin,the micro morphology of various hydration products,metakaolin particles and the interface transition zone between aggregate and cement paste were observed and compared,and the micro mechanism of metakaolin improving the mechanical strength of rubber concrete was analyzed.Figure 36 table 14 reference 107...