Calculation And Evaluation Method Of Crack Resistance Of Mold Bag Concrete

The concrete is a kind of the multiphase and composite material which is low tensile strength and high brittleness and crack width is hard to control.More worthy of attention,there will be some impacts for the safe use of structure crack with reinforced concrete structure for longer duration of use.The aspect of channel lining application is more serious.The mold bag concrete is a new type of channel lining and anti-seepage effect which is a new construction technology.It combines the advantages of traditional concrete and flexible mold bag cloth,which not only can improve the mechanical properties of concrete,but also partially inhibit the development of concrete cracks.But the mold bag concrete volume is larger outdoor,indoor studying mechanical properties is hard to realize.Then the current domestic and foreign scholars on the mechanical behavior of the mold bag concrete theory study also did not observe from the reports,nor a unified standard to evaluate its crack resistance.Therefore based on the mechanism of the mold bag concrete crack resistance,this paper carries on the relevant research.First of all,it is from the perspective of raw material performance and the axial tensile strength and ultimate tensile strain value as an index,which can analyse the variation of cracking resistance of concrete components.Secondly,it is from the perspective of concrete structure and flexural toughness characterization in crack resistance of concrete beams,which can analyze the mold bag fabric on the flexural toughness of concrete beam through the contrast experiment.From the angle of flexural toughness,which can achieve the goal of evaluation mold bag concrete crack resistance.The main research contents are as follows:(1)The research contents include fly ash,gas content,and the aggregate volume fraction on the influence of concrete crack resistance,through the contrast test to discuss mold bag cloth influencing the crack resistance of concrete.(2)Through the ultimate tensile test of equal intensity and strength,the content of fly ash increases,the axial tensile strength and ultimate tensile strength of concrete are increased.With the increase of air content,the axial tensile strength and ultimate tensile strength of concrete show the rule of "middle height and low side".The axial tensile strengthand tensile strength of concrete are decreasing with the volume fraction of coarse aggregate.The axial tensile strength of the mold bag is about 1.1 times the strength of the concrete.The ultimate tensile strain value is about 30% higher than that of plain concrete.The mold bag can improve the comprehensive anti-cracking performance of concrete.(3)By comparing the plain concrete beams and mold bag reinforced beam before fracture and when is fracture of bending toughness through four point bending test.As well as the analysis of mold bag fabric under different strength grade of concrete is impact on the flexural toughness of concrete beam.The cracking in different stages of the mold bag concrete beam of crack extension is in control,researching on different strength grade of mold bags of reinforced concrete beam and flexural toughness of concrete beams.(4)The mold bag fabric can improve the ultimate bearing capacity of concrete beams to a certain extent,confine the deformation of concrete beam and prevent the expansion of the micro cracks of concrete beam.The increase of the absorption energy and equivalent bending strength of the beam is about 16%.The mold bag fabric can in some degree improve the crack resistance of concrete beams.But the bending toughness of concrete beams and the strength grade of the concrete show the curve relation.The experimental results are simulated by ABAQUS finite element software and the correctness of the test results is verified and the two results agree well.