Preparation Technology And Durability Of Red Mud Geopolymer

There are many problems during cement production, such as high energy consumption and high pollution. In addition, a large number of industrial waste residue is not fully utilized in our country every year. As we all know, China is a country with severe energy shortage and environmental pollution. So it is significant to use industrial waste residue of red mud geopolymer to partly replace cement. This paper analyzed the physical and chemical properties of the sintering red mud and studied the effective measures to stimulate the red mud activity. Based on the mix ratio test and design, this paper also studied the molding process of red mud geopolymer to prepare red mud geopolymer of high strength, high mud content, good construction performance and high durability. What’s more, this paper studied the effect of microstructure, phase composition and structure of matrix phase on physical and mechanical properties of materials and analyzed the hydration process of red mud geopolymer based on microscopic test as well. On the base of the above research, this paper evaluated and analyzed the durability performance of alkali activated red mud concrete by analyzing its properties, such as anti-carbonation and anti-chloride ion penetration.From the preparation technology research results of red mud geopolymer, it is showed that chemical activation using water glass as activator is the main approach to activate red mud. It is should be noticed that the sodium hydroxide should be added first then water glass during molding process, and it is better to wrap the samples with plastic film and cover those samples with wet cloth then place the samples in the standard curing room. Red mud geopolymer not only has high early strength, and the late strength increase rate is high. When the content of red mud is no more than 60%, its strength is higher than P.O 42.5 cement. Besides, by comparing with ordinary portland cement concrete, red mud geopolymer has good working and mechanical performance based on the working performance and mechanical performance test of the concrete.It is showed from the micro analysis research of red mud geopolymer that the hardened paste is a material that looks like a rock, hydration product is a kind of geopolymer with Si O2-Al2O3-Ca O-Na2 O system, which is different from ordinary portland cement. The hydration process of red mud geopolymer mainly consists of the polymerization reaction of aluminosilicate, which mainly includes four processes, and they are dissolution hydrolysis, polycondensation and solidification under the condition of alkali activation.It is showed from durability comparison between alkali activated red mud concrete and ordinary Portland cement concrete that, under the condition of high concentration accelerated carbonation, anti-carbonation of the alkali activated red mud concrete is not as good as the ordinary cement concrete. However, there could exist the phenomenon of inverse diffusion of the dissolving alkali in the red mud geopolymer, which could make anti-carbonation of the alkali activated red mud concrete to be much better than the ordinary cement concrete with the condition of low concentration carbonization or natural environment. This means that the conventional method of ASTM C1202 is not suitable for the evaluation of the anti-chloride ion penetration property, while the improved electric quantity method of CSIRO is suitable. Also, when the red mud geopolymer concrete and the ordinary cement concrete are at the same age, as for the electric flux and diffusion coefficient of chloride ion, the former is slightly higher than the latter. But there is bare difference in terms of the anti-chloride ion penetration properties.