Experimental Study On Basic Mechanical Properties Of Gangue Concrete

Coal gangue is the waste rock produced by coal mines.At present,the stock of coal gangue in China is about 7 billion tons,and a large number of coal gangue piles are formed.The harm of coal gangue dump is mainly reflected in occupying a lot of land,polluting the air,destroying the environment and so on.In the current situation of shortage of sand resources for civil engineering,if the treated coal gangue can be used in engineering structure,it will not only absorb a lot of waste coal gangue and reduce the environmental pollution caused by coal gangue,but also broaden the source of sand for engineering concrete and reduce the harm of rock excavation and environmental damage.The main research work of this paper is as follows.In this paper,the coal gangue in Ningtiaota mining area of Yushenfu in Northern Shaanxi Province is taken as the research object,its physical and chemical properties and physical and mechanical properties of aggregate are tested and analyzed,and its applicability as concrete coarse aggregate is explored;then the mechanical properties and various strength indexes of coal gangue concrete are tested and analyzed.This paper studies the physicochemical properties of coal gangue and its physical and mechanical properties when used as concrete coarse aggregate.The radionuclide content,mineral composition,chemical composition,calorific value,carbon content and thermal stability of coal gangue and natural crushed stone were compared and analyzed.The particle gradation,crushing index,bulk density,apparent density,water absorption,mud content and needle like particle content of coal gangue and crushed stone were compared and analyzed.Coal gangue can be used as coarse aggregate of concrete.Taking coal gangue as concrete coarse aggregate,24 groups of mix proportion were designed,180 concrete blocks were made,and cube compressive strength test,splitting tensile strength test,flexural strength test and uniaxial compressive strength test were carried out.Based on the experimental data,the relationship between cube compressive strength and age,splitting tensile strength and cube compressive strength,flexural strength and mix proportion,flexural strength and cube compressive strength of coal gangue concrete are researched.Based on the test results of axial compressive strength of coal gangue concrete,the complete stress-strain curve of uniaxial compression is obtained.There are four stages in the whole process.Due to the brittleness of coal gangue,there is a phenomenon of sudden crush in the descending section.The conversion relations of uniaxial compressive strength,elastic modulus,peak strain and ultimate strain are analyzed by regression analysis of test data,and the constitutive equation of gangue concrete is established.According to the experimental data,the Bolomey formula of gangue concrete and the influence coefficient of gangue replacement rate are established.The Bolomey formula of coal gangue concrete has universal applicability,but the influence coefficient of coal gangue replacement rate has certain discreteness.