Experimental Study On Shrinkage Of High Strength Concrete Reinforced With Studs

With the development of economy and society,the high-rise buildings in our country are constantly emerging.In order to meet the huge bearing capacity of the super-high-rise buildings,high-strength concrete has been widely used.However,a large number of engineering practices show that the self-shrinkage of high-strength concrete is several to ten times larger than that of ordinary concrete,and the drying shrinkage of high-strength concrete is larger than that of itself.In practical engineering,the structure or member which is usually combined with concrete,such as section steel or steel bar,has a large bearing capacity,but the shrinkage of concrete is limited by section steel or steel bar.Similarly,boundary conditions restrict the shrinkage of concrete.In order to study the pore structure characteristics of high strength concrete(HSC)under constraint conditions,the problem of HSC in practical application is effectively solved.In this paper,the mercury injection method,which is widely used in the field of material science,is introduced into the micro-pore structure test of high-strength concrete.The characteristics of concrete pore structure under different restraint degrees and different ages under the same constraint conditions are studied.The research work and main results are as follows:?The basic theory of constrain high strength concrete hole structure is introduced,and the common shrinkage behavior of high strength concrete,such as autogenous shrinkage,drying shrinkage,plastic shrinkage,temperature shrinkage,chemical shrinkage,etc.,including its principle,conditions and influencing factors,are summarized,and the principle,scope and error of the mercury pressure method are introduced in detail.Source analysis.?This paper introduces the definition of constraint,deduces the degree of constraint through the theoretical method of shrinkage of one-dimensional axial concrete member,finds out the necessary method of constraint condition of high-strength concrete,and designs the corresponding test mould.?On the basis of the above theory,the experimental design is carried out to restrain high strength concrete as the research object.It is applied to four constrained states of unconstrained free shrinkage,slight constraint,medium constraint and strong constraint,and on this basis,the comparison of three groups of different maintenance groups is designed for drying maintenance,sealed maintenance and wet curing.The main conclusions are as follows:(a)Under the same curing condition,with the increase of the degree of restraint,the porosity of high-strength concrete is increasing;In the concrete structure,less damage holes and harmful holes increase and the structure is adversely affected.(b)Under the same constraint state,under the condition of wet curing,the porosity of high-strength concrete is the lowest;Under the condition of dry curing,the high-strength concrete has the highest porosity.(c)Provides some theoretical basis for the curing condition of concrete in practical engineering.