Research On Preparation Of Calcined Coal Gangue Powder And Its Influence On Concrete Performance

Mineral admixtures is a Inorganic mineral powder using to the preparation of concrete which can improve the properties of fresh concrete and hardened concrete. As a kind of auxiliary cementitious materials, mineral admixtures has become to the sixth indispensable component of HPC. Calcined coal gangue as mineral admixtures, first it can reduce the dosage of cement and reduce the energy consumption; second turning coal gangue into treasure can reduce environmental pollution; third it can improve the properties of concrete and the quality of engineering, which is an important way to realize coal gangue resource utilization. This subject is funded by the committee project of National Natural Science and the limited company of ShenHua group, it is the subprojects of the (U1261122), All results of the studies are in the fund of the project.At first, this paper adopts the composite method of thermal activation and mechanical activation, stimulate the potential activity of coal gangue. Next through the coal gangue cement mortar fluidity and strength test, the calcination temperature of coal gangue and the best grinding time were determined; On this basis, taking admixture mixed breeds and composite volume as 2 influencing factors, and through the orthogonal experiment of the concrete consistency and strength test to study the its influence on the mixing of concrete workability, and compressive strength of 7d,28d, 60d,90d. Give the optimum mixture ratio.Last using the optimal mixing proportion, the compressive strength, splitting tensile strength, resistance to chloride ion penetration and resistance to freeze-thaw cycles were also studied..And had achieved some main research results:(1) Unburned coal gangue of Fuxin QingHemen, after the mechanical and heat treatment,it meet the basic requirements of concrete admixture.and it is feasible to be as concrete admixture.(2) Taking calcined coal gangue powder as mineral admixture of concrete can significantly improve the performance of fresh concrete, reduce slump loss and improve the pumpability of concrete. In terms of improving concrete workability, calcined coal gangue powder has more than the same fineness of slag excellent performance, but slightly inferior to fly ash.(3) The activity of calcined coal gangue powder is between fly ash and slag and when used as admixture in concrete, can have volcano ash effect and a bigger contribution to the late strength improving rate of concrete.(4) Fly ash, slag, when mixed with calcined coal gangue powder respectively, with the increasing of calcined coal gangue powder, strength of concrete first increases and then decreases. When calcined coal gangue powder mixed both with ratio of 3:7, the concrete compressive strength of 28d reach to the Maximum.(5) For the resistance to chloride ion permeability, when fly ash, slag, mixed with calcined coal gangue powder, the permeability grade is middle. For the resistance to freeze-thaw, the freezing-thawing resisting can reach 550 times when fly ash mixed with calcined coal gangue powder, but 500 times when mixed with slag. General speaking, the mixing between fly ash and calcined coal gangue powder had a better compatibility than the slag.