Coal Gangue Based Geopolymer Preparation And Compressive Strength Prediction Of Coal Gangue Based Geopolymer Concrete

Coal gangue is waste from coal mining and processing,increasing rapidly per year.Emission,processing and accumulating of coal gangue impose a severe negative effect on environment.Thus,utilizing coal gangue in a reasonable and effective way is vital.Geopolymer,recently developed as a new inorganic nonmetal cementitious material,is produced by the reaction of solid silicate or aluminosilicate powder and alkali metal hydroxides/alkaline silicate,listed as energy conservation and emission reduction material in national twelfth five-year plan.Main mineral composition of coal gangue is silicate and aluminosilicate,and coal gangue can be raw material for making geopolymer.Coal wastes such as coal gangue will be utilized as raw material for making geopolymer and geopolymer concrete.The compressive strength and mix design based on intelligent algorithms are predicted and optimized,respectively.And high-temperature performance of the geopolymer concrete component are studied using finite element theory.The main research work are as follows:1.Sodium hydroxide and calcium carbonate were mixed together to produce alkaline dry powder activator to replace traditional hydroxide activator solution.Preparation of geopolymer cementitious material was proposed with coal gangue,fly ash,standard sand and the dry powder activator.Compared with traditional sodium hydroxide solution activator,experiments were carried out to study setting time,absorption rate and compressive strength of the geopolymer activated by the alkaline dry powder.Effects of sodium hydroxide and calcium carbonate amount in alkaline dry powder activator on setting time and absorption rate were revealed,obtaining important parameters by analysis.Effects of curing time and curing temperature on basic behaviour of the geopolymer were analyzed.And polymerization mechanism of alkaline dry powder activated coal gangue based geopolymer was revealed.2.Coal gangue based geopolymer concrete was prepared by mixing alkaline dry powder activator,coal gangue and fly ash as cementing materials.The basic mechanical properties such as compressive strength and rupture strength of the coal gangue based geopolymer concrete were studied by concrete mechnical test methods.Developing rules of coal gangue based geopolymer concrete mechanical properties with different activators were analyzed compared with ordinary concrete.Effects of curing temperature,curing time,water-cement ratio and sand ratio on alkaline activated coal gangue geopolymer concrete were analyzed,and optimum curing temperature,water-cement ratio and sand ratio were obtained,respectively.3.Support vector machine and modified cuckoo algorithm were utilized to predict compressive strength of geopolymer concrete.A prediction algorithm was proposed by introducing an orthogonal factor to modify traditional cuckoo algorithm to optimize the parameters in the support vector machine model.Compressive strength prediction model for coal guague based geopolymer concrete was established based on oxide contents in raw materials,where oxide contents in raw materials were input,and compressive strength of the geopolymer concrete were output.By analyzing the prediction results,developing rules of compressive strength of geopolymer concrete with oxide contents variation were obtained.4.The intelligent optimization method is employed to study the mix design of coal gangue based geopolymer concrete.Gravitational search algorithm was modified based on Chebyshev map in chaotic theory,and the modified equations was derived.To guarantee the strength and workability,with the target to minimize the cost of geopolymer concrete,the framework of the mix design optimization was established.Through analysis of the optimization results,cost variation of different strength grade coal gangue based geopolymer concrete were revealed.5.High-temperate characteristics of coal gangue based geopolymer concrete beam are studied by finite element method.Finite element models of beams with different cross section dimensions were established.Temperature distribution and deformation of the beams from room temperature to fairly high temperature were studied.Under different high temperature working conditions,cracking load and limit load of the geopolymer beams with different concrete cover thickness are analyzed.Deformation and capacity behavior principles of coal gangue based geopolymer concrete beams were obtained.