Research On Rebound Test Based On Early Compressive Strength Of Grouting Standard Test Block

The cement-based grouting material is composed of high-strength cementitious materials,various functional admixtures and selected aggregates.It has the advantages of super adhesion,early strength,high strength,micro expansion and large fluidity.It is mainly used for the reinforcement and repair of concrete structures,such as the defect reinforcement and repair of high-strength concrete,the reinforcement and reconstruction of concrete structures,the secondary grouting of equipment foundation,anchor bolt anchoring and the reinforcement of dry-type wrapped steel Wait.The strength of grouting material is not only related to cementitious materials,admixtures and other factors,but also closely related to the changes of its geometric size and geometry.With the development of my country’s construction industry,many existing buildings have entered the stage of repair and reinforcement.Grouting is widely used in them due to its many advantages,such as easy construction,micro expansion,early strength and high strength,and better fluidity.And the reinforcement effect is good.Due to the increasing use of grouting materials in reinforcement projects,in order to ensure construction progress and safety,it is becoming more and more important to conduct research on the early strength of cement-based grouting materials.This paper mainly studies the early compressive strength of grouting materials from the following three aspects:(1)The compressive strength of standard test block and non-standard test block is compared and analyzed for the third and fourth class grouting materials.In the actual engineering or laboratory,because it is often impossible to use standard size test blocks,for example,when making the rebound strength measurement curve of grouting materials,in order to facilitate rebound on the test block press,150 mm cubeis often selected as the test object,while 40 × 40 × 160 mm prism test pieces shall be used for the standard test pieces of class Ⅲ grouting materials,and 40 × 40 × 160 mm prism test pieces shall be used for the standard test pieces of class Ⅳ grouting materials It is necessary to analyze the compressive strength of the test pieces with different sizes of the test mold by using the 100 × 100 × 100 mm cube test pieces,and obtain the conversion coefficient of the early compressive strength of the standard size test pieces and the non-standard size test pieces of the two types of grouting materials,so as to provide reference for the early compressive strength test of the grouting materials by rebound method and the actual project.(2)Use the finite element analysis software ANSYS/LS-DYNA to simulate and analyze the impact point,vertical pressure,test block size and the impact of different impact energy on the rebound value of the grout.(3)Based on the regression analysis of the compressive strength and rebound value of the standard test block,the rebound strength curve of the early compressive strength of the Ⅲ and Ⅳ grouting materials for practical engineering is obtained.In the test,a total of 252 grouting test blocks of Type Ⅲ and Ⅳ were produced,and the two types of materials were divided into 14 ages,and they were subjected to rebound and compression tests.The compressive strength of non-standard test blocks was converted into standard tests.Block compressive strength to study the relationship between the rebound value and the early compressive strength of standard grout test blocks.Through regression analysis and research on the test data using different functional formulas,the formulas for the rebound strength of the early compressive strength of the Ⅲ and Ⅳ grouting materials are respectively proposed.