Study on the geopolymers has been a history of nearly 40 years, because of its huge comparative advantage and attractive prospect, has become a hot research field of international materials.In this paper, based on the history and the present status of geopolymers cementitious materials development, summarized geopolymer cementitious material in the selection of raw materials, the activation agent development,preparation process research, cementitious material properties, mechanical properties, durability and engineering applications. progress made and trends.On this basis, expounded the problem of large-scale widely used the geopolymers need to continue to address, and pointed out the direction for its further research and application.
A kind of straw returning and fertilization seeder was designed. The overall structure and key technologies were introduced. The structures and parameters of the key parts were determined. The teamwork machine has a reasonable and compact structure and wide applicability, which can realize straw chopping, tillage, soil preparation, seeding, fertilization and compacting.
Through the experiment, this paper studies and analyzes influence of different initial temperatures on cement grout performance. The results show initial temperature has influences on grout fluidity, bleeding rate, setting time and early strength. Under guaranteed curing temperature, initial temperature has no influence on long-term strength of grout.
This paper discusses the reason of segregation of expanded perlite lightweight aggregate concrete. By adding fly ash, high effective admixture, the expanded perlite pre-wetting and so on,the expanded perlite lightweight concrete,CL5-CL10,was confect with good workability, homogeneity, no bleeding and segregation, easy casting and excavation.
In consideration of few researches on model materials of soft rock tunnel model test, and the problems such as high price of raw material, difficult availability of materials in market, and weak universality existing in the materials which can be used as reference, this paper researches and develops the model materials with low price, wide source, and strong universality. The application result shows that the developed model materials can meet soft rock model test requirements, and they can be reused within 3 months.
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