The Influence Of Common Mineral Admixtures On The Performance Of Cement-based Materials

Nowadays, the construction industry has become an important material-producing branch of our national economy. It is not only related to the country’s overall economic development closely, but also linked to improve people’s quality of life inextricably. In the construction industry area, cement has become one of the main raw materials of basic construction, possessd an extremely significant position. It is widely used in many important national pillar industries, such as industry, national defense, transportation, water conservancy fields, etc, because of its such traits as fast hydration process, fast setting hardening process, high strength. At the same time, the serious environmental problems caused by cement production process has become one of the major factors hindering economic development. On the other hand, with the rapid development of industrialization, generate a lot of industrial wastes which can not be digested by environment, such as fly ash, slag, silica fume, coal gangue, etc. These industrial wastes can not be rational used, resulting in unreasonable dumps, not only take up a lot of land, but also pollute the environment seriously. So, how to combine the industrial wastes in the form of mineral admixture or cement mixed materials with cement clinker through reasonable design has become an urgent problem. This topic will not only reduce the usage of cement clinker, reduce the environmental pollution problems which from cement production process, but also can effectively use up large amounts of industrial wastes effectively, embark on a path of sustainable development.In this paper, by the reaction degree of cementitious materials in composite cement pastes with qualitative and quantitative measurements to assessd the mineral admixtures of composite cement pastes contribution made to the system. Researched on the change rules of reaction degree of cementitious materials in different mixing proportions and different curing ages, combined with drying shrinkage and compressive strength datas of the composite materials, looking for the best cementitious materials ratio of the composite system.This paper is divided into three parts to study the contribution of mineral admixtures of composite cement pastes made on system. 1) Using non-evaporable method, selective dissolution method and computer method to measure the reaction degree of cement and mineral admixture in fly ash-cement binary system and fly ash-silica fume-cement ternary system, and combined datas of drying shrinkage and compressive strength to analysis the influence of curing age and mixing proportion on non-evaprorable water, reaction degree, drying shrinkage, compressive strength and the relationship between the various performances, looking for the best cementitious materials ratio of the composite system. 2) Using non-evaporable method, selective dissolution method and computer method to measure the reaction degree of cement, coal gangue and slag in coal gangue-cement, slag-cement binary system and coal gangue-slag-cement ternary system, and combined datas of drying shrinkage and compressive strength to analysis the influence of curing age and mixing proportion on non-evaprorable water, reaction degree, drying shrinkage, compressive strength and the relationship between the various performances, looking for the best cementitious materials ratio of the composite system.3) Using thermal analysis method to measure Ca(OH)2 content of fly ash- cement binary system and fly ash-silica fume-cement ternary system to characterize the reaction degree of cementitious materials in composite system, and combined datas of drying shrinkage and compressive strength to analysis the influence of curing age and mixing proportion on Ca(OH)2 content, drying shrinkage, compressive strength and the relationship between various performances, looking for the best cementitious materials ratio of the composite system.It is concluded that:1) Considering the reaction degree of cement, mineral admixture of fly ash-cement binary and fly ash-silica fume-cement ternary system, drying shrinkage and compressive strength of the cement-based composite materials. The results shown that composite cementitious material containing 5% silica fume and 45% fly ash can meet the composite material which has small drying shrinkage and high compressive strength and the utilization of mineral admixtures is the largest.2) Considering the reaction degree of cement, coal gangue, slag of the coal gangue-cement, slag-cement binary system, coal gangue-slag-cement ternary system, drying shrinkage and compressive strength of the cement-based composite materials. The results shown that composite cement paste containing 15% coal gangue and 15% slag can meet the composite material which has small drying shrinkage, high compressive strength and the utilization of coal gangue and slag is the largest.3) Considering the Ca(OH)2 content of cement, fly ash-cement binary system, fly ash-silica fume-cement ternary system, drying shrinkage and compressive strength of the cement-based composite materials. The results shown that composite cement paste containing 30% fly ash and 10% silica fume can meet the composite material which has small drying shrinkage, high compressive strength.