Research On The Properties And Application Of Alkali-activated Gypsum Composite Cementitious Materials

With the rapid development of urbanization,building energy consumption has become an adverse factor restricting the development of traditional construction industry.Traditional building materials need to seek technological breakthroughs.The development of energy-saving and environmentally friendly green buildings is a significant and urgent task in our country.As a "green building materials",gypsum has great application potential in the construction field.Further exerting the outstanding advantages of gypsum-based materials in energy saving and environmental protection is in line with the actual needs of the current construction field and the requirements for the development of national conditions,and is also an important measure to promote the early realization of the national green building strategy.How to effectively tap the application potential of gypsum-based materials in the field of construction has become a hot research topic of experts and scholars at home and abroad.In this thesis,based on the research of alkali-excited gypsum composite cementitious material,alkali-excited gypsum composite cementitious material based on ? type semi-hydrated gypsum has been prepared and optimal ratio has been obtained through a variety of proportions of the trial mix and effect comparison.The main physical and mechanical properties were evaluated by making the specimens,which show that it has the characteristics of light weight,high strength and good water resistance.Scanning electron microscope was used to observe and analyze the microstructure.It was found that the microstructure of its grains show a tight and stable network structure,good grain size distribution.Therefore,high density,high strength,and good water resistance were shown in its macroscopic properties.The alkali-activated gypsum composite cementitious material can be made into blocks and built into walls.In order to study the mechanical properties of such wall structures under the combined influence of vertical loads(from wall self-weight,floor/roof loads,etc.)and horizontal actions(wind loads,horizontal earthquakes,etc.),three vertical uniform loads of2.0k N/m2,4.0k N/m2,and 6.0k N/m2 and three horizontal displacements of 0.025 m,0.04 m,and0.05 m were combined into nine different load conditions.Based on the three-dimensional solid element of concrete damage-plasticity criterion,a simplified micro-separated modeling method was proposed to carry out refined finite element modeling of block walls.Through the block constitutive model and the bond-slip interface constitutive model,the key parameters required for modeling were obtained.Subsequently,the ABAQUS finite element modeling was performed on the block walls of the selected size,and the results under different actual working conditions were obtained.The performance study of the block wall under the combined effect of vertical load and horizontal displacement was completed,which provides a technical reference for the engineering application of this type of wall.Blocks made of alkali-activated gypsum composite cementitious materials can also be used to improve the energy saving,environmental protection and construction convenience of traditional brick flat arch structures.A special study was conducted in this paper.The bearing capacity analysis method of such high-strength gypsum block flat arches was theoretically given,which can be used for the safety design of new flat arches and the safety check of existing flat arches.At the same time,the anti-deformation ability of the high-strength gypsum block flat arch was analyzed,and the method for determining the flexural stiffness was obtained.Subsequently,the rationality of the analytical method was verified by the experimental method and the key parameters were determined.Based on the research results,the engineering application suggestions for the high-strength gypsum block flat arch were proposed.