Research Of The Performance Of High Performance Gangue Concrete

Coal gangue is a coal mining and coal oil refining production in the process of industrial wastes.Long term and gradually abandoned not only occupy a lot of land, but also in a certain condition of spontaneous combustion, causing serious environmental pollution to the air and groundwater.These coal gangue, although a source of pollution, but also is an available resource, as long as the rational use, you can change waste into treasure. At present, part of the coal gangue are mainly used as raw materials for the preparation of ceramics, refractory, cement, etc.,but the utilization of coal gangue is still less than 70%. With the development of social economy, environment and resources, harmless application of coal gangue has been widespread concern, especially to realize the effective utilization of high added value has significant social value, environmental value and economic value.Coal gangue containing Fe2O3, TiO2, K2O, Na2O, CaO and other oxides, the main composite of mineral is kaolinite.Coal gangue calcined with spontaneous combustion leads to dehydration and decomposition of kaolinite, which make it has ash activity,so the coal gangue can partly replace aggregate to make green high performance concrete This paper firstly studies the physical properties of coal gangue as coarse aggregate, including distribution, apparent density, water absorption, crush index, clay content,and XRD was used to analyze the phase composition of coal gangue.Through the research on the basic test, find out the suitable range of factors such as the best replacement of coal gangue,water/binder ratio, dosage of water reducing agent and the dosage of silica fume. Then using orthogonal test method and the overall balance method to get the best mix of gangue concrete,analyzed the workability of the coal gangue concrete (slump, air content, the losses), the main factors affecting the development of strength and water/binder ratio,dosage of coal gangue,water reducing agent and mineral admixtures etc. such main factors influence on the resistance to chloride ion penetration and carbonation resistance of coal gangue concrete.Finally using SEM observation the microstructure and morphology of the coal gangue concrete.Experimental research shows that::The silt content of coal gangue is larger, it’s one of the main factors influencing the workability, it need to be deal with before using. The apparent density and crush index of coal gangue is Close with gravel, Preparation of C50 concrete, the average strength of 28d can be 54 Mpa. When Coal gangue concrete content is 40%～60%,its mechanical properties will be the best, The coal gangue after spontaneous combustion has pozzolanic effect, To participate in further hydration make compressive strength guaranteed, Under the optimal ratio of mixture of coal gangue concrete compressive strength can reach 54.71 MPa. The bibulous rate of coal gangue is bigger, it have a certain influence on the workability, High water cement ratio and low dosage of silica fume can improve the workability of coal gangue concrete. In the preparation of concrete slump, the optimal proportion design requirements can be up to 190 mm.In the four factors orthogonal test, Water/cement ratio and the dosage of silica fume on the chloride ion penetration and carbonation performance impact is very significant, the affect of gangue Coal is lower, The impact of water reducing agent.is not very big. Under the optimal ratio of mixture of coal gangue concrete, its 6 h electric flux can be up to 943.25 C, Similar to those of normal concrete with resistance to chloride ion penetration performance. The coal gangue concrete carbonation of 28d is 4.1 mm deep., It’s carbonation depth is similar to normal concrete under the same ratio. Content of coal gangue is seriously influenced on the shrinkage of concrete, in this experiment, at 40%, coal not only ensure the coal gangue concrete resistance to chloride ion penetration and carbonation resistance performance, and reduce the shrinkage of concrete to a minimum As can be seen from the SEM analysis, Coal gangue concrete has a more compact structure, Spontaneous combustion of coal gangue pozzolanic effect to participate in the hydration reaction, formation of calcium silicate gel network, to fill the gaps between the aggregate, The coal gangue concrete structure more compact as a whole, in order to lower the transmission speed of the chloridion, and reduce the transmission path of CO2. To improve the durability and compressive strength of the coal gangue concrete.