Study On Preparation And Dynamic Properties Of Polymer Modified Cement Mortar

In practical applications,many concrete structures are designed to withstand the effects of external forces such as shock,explosion,earthquake,etc.It is very important to choose a good way to reinforce and maintain the existing reinforced concrete structure.The high strength wire mesh-polymer modified cement mortar reinforcement is a new reinforcement method which is now the new development,fire resistance and good durability,reinforcement technology of concrete structure has become a widespread concern of scholars at home and abroad.The performance of high performance mortar plays an important role in the strengthening process,and the dynamic mechanical properties of polymer modified cement mortar are seldom studied.In order to expand the application range of the reinforcement technology in the field of blast and shock resistance,it is necessary to develop a high performance mortar.In this paper,the research and development of high performance mortar are studied systematically.The main work is done in two aspects: First,the effect of the ratio of mixed mortar on the mechanical properties of mortar;The second is to study the strain rate effect and nonlinear damage constitutive relation.Specific research results and conclusions are as follows:1.Test for high strength steel wire mesh and polymer modified cement mortar with high performance mortar technology in,This test is studied under the condition of water cement ratio,mixing amount of rubber powder,powder water reducing agent dosage,fiber content on the properties and durability of mortar compressive strength,flexural strength,adhesion properties and fluidity of mechanics,the results are as follows:(1)determination of mechanical properties and construction performance can meet the requirements of the design requirements of concrete structure reinforcement,which is the ratio of water to binder,the ratio of binder to sand is about 2,the content of powder is about 2%,and the fiber content is about 0.15%.(2)the compressive strength,flexural strength and bond strength of the mortar were greatly improved when the polymer content was about 2%;With the increase of water to binder ratio,the compressive strength,flexural strength and interfacial bond strength of mortar decreased,and the fluidity increased.When the fiber content was 0.15%,the durability,crack resistance and toughness of mortar increased significantly;The powder of superplasticizer in the range of 0.4%-0.6% on mortar compressive strength and flexural strength and other mechanical properties of no significant change,mainly on the construction performance and precausions mortar fluidity influence.2 The impact failure mode and strain rate effect of the mortar were studied by Hopkinson compression bar(SHPB)impact compression test.The results show that:(1)Polymer modified cement mortar is a strain rate sensitive material.The dynamic strength of mortar increases with the increase of strain rate,and the strain rate effect decreases with the increase of mortar strength.The elastic modulus decreases gradually with the increase of strain rate.(2)with the increase of loading rate,the failure mode of the mortar block is significant,It can be divided into: crack free,small amount of cracks,large number of cracks,the integrity of a large number of cracks and the integrity of the poor,such as smash destruction.(3)When the impact velocity and fiber content are certain,the greater the mortar strength,the smaller the damage degree of the test block,that is,the less the crack and the lower the degree of fragmentation;(4)When the mortar strength is 60 MPa and 50 MPa,with the increase of fiber content,the peak stress,the peak toughness and the ultimate toughness of mortar increase first and then decrease,and the effect is higher than that of 70 MPa mortar;Compared with PVA mortar and PF mortar,steel fiber mortar can improve the toughness and impact resistance of mortar,and the effect is more obvious.(5)According to the experimental data,the ZWT constitutive model fitted well with the experimental stress-strain curve.The model can be used to describe the constitutive relation of mortar under different strain rates.