Research On Mathematical Model Estimation Of Compressive Strength Of Nondestructive Testing Of Gangue Concret

Coal gangue,as a companion of coal production,has not been used much in people ’s life and will accumulate and cause environmental pollution.Because coal gangue is light,it can be used as coarse aggregate in lightweight aggregate concrete for waste recycling production and reuse.Nondestructive testing technology can detect the compressive strength performance at this time without destroying the original building foundation.At present,the rebound method and ultrasonic rebound comprehensive method of ordinary concrete have a national unified strength curve,while lightweight aggregate concrete is not applicable.Therefore,rebound method,ultrasonic method and ultrasonic rebound comprehensive method are used as influencing factors to study,and the mathematical model of non-destructive testing prediction of coal gangue concrete is obtained.The mathematical model provides a theoretical basis and regular reference for the establishment of special coal gangue concrete strength curve in the future.The main research contents of this paper are as follows :(1)In this paper,different kinds of mix ratios and two kinds of coal gangue were adopted.Four kinds of coal gangue content and four different net water cement ratios were prepared for each kind of coal gangue.The first kind of coal gangue was cured by7 d,14d and 28 d respectively.The second kind of coal gangue was cured by 7d standard curing.A total of 192 concrete specimens were tested.The rebound test,ultrasonic test and compressive strength test were carried out respectively.(2)Based on the compressive strength test results,the compressive strength of coal gangue concrete under different dosage and different ages is analyzed.The early strength of coal gangue concrete is great.The strength of coal gangue concrete at 7d has reached 85.6 % of 28 d,and the lowest will reach 76.6 % of 28 d.The compressive strength of 70 % coal gangue concrete is the largest at 7d,14 d and 28 d compared with other concrete with the same net water cement ratio.(3)The ultrasonic-rebound combined method was analyzed and fitted by SPSS and Origin software.The relative coefficient and significance standard were analyzed,and the optimal fitting model was obtained respectively.The average relative error and relative standard deviation of the optimal fitting model are within the range of the error specification of the special strength curve.