Research On Performance And Mechanism Of Mortar And Concrete Using Soda Residue As Mineral Admiture

Soda residue is a kind of waste when the traditional soda production technology solvay process is adopted, its stockpiling and emission have caused serious resource and environmental problems.The governance of soda residue is a world wide problem now, so most of the developed countries have abandoned the solvay process to seek a new technology. But China is a developing country, the industrial development level relatively backward, relinquish the soda process of solvay does not conform to the current national conditions, the comprehensive utilization of the waste is the only way to the govern of soda residue, so that the resource and environmental issues can be resolved and turn waste into treasure.So far, the soda residue has been widespread used in many fields such as the agriculture, chemicals and building materials, and has achieved some achievement. But the low utilization is the main problem currently, and the rate of multipurpose utilization is less than 16% in our country. That reason is the low requirement in the field of agriculture and chemicals, although the building materials field has a higher demand than the other two, the high levels of chloride ion in soda residue will seriously threaten the durability of building structures, thus its widespread use is restrained.View of the above problems, this article firstly studied the phase composition and microstructure of soda residue, on this basis, studied the soda residue chloride ion dissolution features with the different treatment of soaking, grinding, washing and electroosmosis. Further studied the mortar and concrete mixture ratio when soda residue was mixed in, and choose to optimize mixture ratio, studied the influence on mortar and concrete performance when different treatment of soda residue were mixed in. Comprehensive analysis of the suitable processing and application way when soda residue was used as the mortar and concrete admixture.(1)By microscopic analysis techniques of XRF and XRD and DTA studied the soda residue chemical composition and phase composition, the results show that soda residue main phase for calcium carbonate, gypsum and calcium chloride. By SEM morphology analysis, laser particle size analysis, mercury intrusion pore size analysis and nitrogen adsorption ratio surface area analysis studied the microscopic structure of soda residue, the results show that the microcosmic structure can be formulated as follows: some nanometer calcium carbonate consists of the size 2-5um reunion particles; a part of reunion particles can gather and form the larger size of 10-74 um aggregate particles; the aggregate particles are overlapping and accumulation each other, so consists of the macro morphology of the soda residue.Soda residue have the developed pore structure system. Including the space between the aggregate particles, the pore structure inside of the aggregate particles and the nanoscale pores inside of the reunion particles.(2)Soaking test studied the dissolution characteristics of chlorine ion in space when the aggregate is dispersived by water; Grinding test studied the chloride ion dissolution characteristics by damaging micron grade pore internal aggregate; Washing test studied the chloride ion dissolution characteristics of micron grade pore internal of the aggregate particles by increasing the ratio of water to solid Electroosmosis test studied the further dissolution of chloride ion in nano porous with electric fields. The results show that soda residue chlorine ion mainly exist in the space between the aggregate particles, some exist in the micron grade pore internal aggregate, the nanoscale pores inside of the reunion particles is extremely low. The distribution of chlorine ion in soda residue is that: space contains 73% levels, micro pore contains 20% and nano porous contains 7%.The suitable measure of removing soda residue chloride ion is washing.(3)By orthogonal test studied the optimum combination of mortar cementmaterials; With optimized combination of gelled material matching, we studied the influence of the original soda residue, the washing soda residue and the removal of chloride ion soda residue to the mortar performance, and studied the feasibility of using removal of chloride ion soda residue as the water retention agent in mortar. The results show that, the removal of chloride ion soda residue which chloride ion content is lower than 0.3% can be used as mineral admixtures on mortar. The best content of the removal of chloride ion soda residue is 10% to15%, a more better content of fly ash is 10% to 20%, mineral powder is 10% to 20%. In addition to chlorine soda residue replace 15% fly ash, The 28 d compressive strength of mortar can be increased by 74%, The gelled material soluble chloride content is below the limit of-D environment(0.1%) and can meet the requirements of durability. mortar soluble chloride leaching content is far lower than the groundwater discharge limits, won’t cause the underground water pollution. Its water performance is superior to the traditional water retention agent, can be used as the water retention agent,appropriate to add subtract water regulating consistency.(4)By the single mixing and the double mixing test studied the optimum combination of concrete cementmaterials, With optimized combination of gelled material matching, we studied the influence of the original soda residue, the washing soda residue and the removal of chloride ion soda residue to the concrete mechanical properties and durability and the environment.The results show that, the appropriate mix content of the soda residue is 10%, the fly ash is 10% to20%, mineral powder is 10% to20%. Using soda residue to replace 10% of the fly ash and the cement, the concrete strength will increase. The original soda residue and the soda residue washing one times both can cause steel corrosion, and can’t meet the requirement of the durability. The removal of chloride ion soda residue will not cause steel corrosion, and the half cell potential measurements is far lower than the steel bar corrosion potential critical value, and is very close to the blank group without soda residue, which can be used as mineral admixtures on concrete to popularize.