Establishment And Application Of Rebound Strength Measurement Curve Of Pumped Concrete In Huainan Area

At present,the construction authorities in Huainan area attach great importance to the sampling inspection of the main structure entities,and regard the sampling inspection results of concrete strength and cast-in-place slab thickness as the important basis for the inspection and acceptance of the main structure entities.As a quick and convenient detection method,rebound method is often used for random inspection of concrete strength.When the sampling results are unqualified,it is the most common treatment method to carry out rebound-core drilling test based on batch testing.Combined with 40 groups of samples from rebound-core testing statistics during 2020-2021,it can be seen that the maximum positive deviation between the compressive strength value of core samples and the strength value of the national unified strength measurement curve in the measured area is 23.0MPa,and the maximum negative deviation is-5.9MPa,with 37 positive deviations,2 negative deviations and 1 sample without deviation,which shows that the concrete strength estimated by the national unified strength measurement curve is lower than the actual value of core samples.Therefore,it is urgent to improve the detection accuracy of rebound method in Huainan area.Based on this situation,the main research contents of this paper are as follows:1.By analyzing the application of rebound method in Huainan area in recent two years,combining with the principle of rebound method and main influencing factors,this paper determines the strength measurement curve of local pumped concrete suitable for Huainan area as the research content.2.By analyzing the basic situation of concrete raw materials such as 34 groups of concrete stones,70 groups of concrete sands and 31 groups of concrete cements,which are mainly produced in Huainan and its surrounding areas in recent two years,and making use of the existing resources of 43 mixing stations in Huainan,this paper formulates the research scheme of this subject.3.In this paper,the regression equations of linear functionfcu,ic=a+bR.Binarylinear power function fcu,ic=a+bdm,i+cR,a power functionandfcu,ic=aRb and power function fcu,ic=a·10bdm Rc are derived respectively,and the power function is mainly used as the basis for data processing according to the specification requirements.4.In this paper,797 groups of valid data are collected through experiments,and the recommended strength measurement curve of pumped concrete in Huainan area is obtained by regression curve equation f=0.052656 R1.825757 10-0.012489dm,δ=±9.53%;er=11.08%,R=0.9874.By analyzing and comparing the proposed curve with the national unified strength measurement curve and Anhui strength measurement curve,it is pointed out that Huainan strength measurement curve has the best applicability.5.In this paper,combined with the engineering application suggested in Huainan area,the two recent test results of a project in Huainan area were analyzed by using the national unified,Anhui and Huainan area suggested strength curves respectively,and the Huainan area suggested strength curves were applied to the project,which showed that the Huainan area suggested strength curves had the highest accuracy.Figure [20],table [22] and reference [51]...