Study On Mechanical Properties Of Coal Gangue Concrete

Concrete has been widely used in building engineering,quality of aggregate accounted for more than 2/3 of concrete quality,production of concrete aggregate consumed a large amount of natural resources.Coal gangue is a kind of industrial waste with coal mining.In China,there were billions of tons of coal gangue with coal mining,the pile of coal gangue lead to occupation of cultivated land and environment pollution.Scientists have carried out research on production of concrete with coal gangue,some progress has been made.But most of the research was focused on production,workability,strength and durability of coal gangue concrete,lacked of research on deformation of coal gangue concrete.Strength,elastic modulus and Poisson's ratio were important parameters of concrete.The relationship of stress,stress and strain,longitudinal and transverse deformation were not only important parameters when analysis the stress state and deformation performance of concrete,but also basis of concrete structure,crack propagation and mass concrete temperature stress calculation.In this paper,coal gangue was made by Hualong group.Test the technical parameters of coal gangue,compare and analysis performance of ordinary gravel and coal gangue,produce concrete with coal gangue.According to concrete mix design procedure,use ordinary gravel produce four strength grades(C20,C30,C40,C50)concrete,slump of concrete was 180 +20mm.Replace ordinary gravel with coal gangue in the proportion of the 20%,40%,60%,80%,100%.Adjust the workability of concrete with admixture,test the strength and strain of concrete with pressure testing machine and D3820 data acquisition,resistance strain gauge.The influence of coal gangue replacement rate on concrete workability,strength,specific strength,elastic modulus and Poisson's ratio was studied.Establish mathematical model of coal gangue concrete strength,apparent density,elastic modulus.It provided the basis for the structure design of coal gangue concrete and lie foundation for the application of coal gangue concrete.Experimental results showed:the fluidity of concrete was gradually decreased with increase of coal gangue replacement rate.If you want to keep requirements of design flow,gradually increase the amount of water reducing agent.When gravel was replaced by coal gangue totally,the dosage of water reducing agent was increased by 3%.Coal gangue replacement rate had little influence on strength of C20 concrete.When the coal gangue content was increased to 60,strength of C30 concrete was decreased by 10%,coal gangue replacement rate should be less than 40%.When the coal gangue replacement rate was 40%,strength of C40 and C50 concrete was decreased by 14%,coal gangue replacement rate should be less than 20%.Influence of coal gangue replacement rate on concrete strength was proved by experimental results of axial compressive strength.Elastic modulus was fluctuated in the range of ± 1GPa with increase of coal gangue replacement rate.C30 coal gangue concrete was mostly decrease by 1.3GPa,C50 coal gangue concrete without gravel was decrease by 10%.The measured results of coal gangue concrete Poisson's ratio conformed to Poisson's ratio of high performance concrete.Through the verification of Liaoning Province outstanding talent project,workability of C40 concrete which was 7m3 and coal gangue replacement rate was 20%can meet application requirements.The 28d measured compressive strength of test piece was 48.3MPa with the same conditions of pouring and curing.According to the experimental results of elastic modulus,apparent density and strength of coal gangue concrete,elastic modulus mathematical model of coal gangue concrete was Ec=429.1/(9.003+151.4/fc).According to the experimental results of elastic modulus,and strength of coal gangue concrete,elastic modulus mathematical model of coal gangue concrete was Ec= 6.036×10-3×?×fc0.2388?Elastic modulus mathematical model was verified by the test results of the elastic modulus of coal gangue concrete,the relative error was less than 10%?According to calculation result of elastic modulus calculation formula which was presented in GB50010,AASHTO and 13-ACI318M-05,the relative error of fitting curvewas small.