Alkali-activated carbonate composite cementing material and preparation method thereof

Abstract

The invention provides an alkali-activated carbonate composite cementing material and a preparation method thereof. Modified sodium silicate solution and solid powder material are weighed at the mass ratio of (0.6-1.0):1; in the preparation process, under the stirring of 60-120 turns / min, the solid powder material is slowly added into the modified sodium silicate solution to continuously stir for 3-5 minutes to obtain the alkali-activated composite cementing material, wherein the modified sodium silicate solution is prepared in the following steps: sodium hydroxide is dissolved in liquid sodium silicate, or sodium hydroxide and solid sodium silicate are dissolved in water together and the obtained product is continuously stirred until solution is transparent; the modulus of the obtained sodium silicate solution, i.e. the mass ratio of silica and sodium oxide is 1.2-2.0, and the mass concentration sum of the silica and the sodium oxide is 25-45%; the solid powder material is prepared from the following components in parts by weight: 15-30 parts of slag, 5-20 parts of coal ash, 10-30 parts of metakaolin and 20-70 parts of dolomite dust or limestone powder; and the above raw materials are successively arranged in a blender mixer and are stirred at normal pressure and temperature at 60-120 turns / min for 5-15 minutes to obtain the finished product.

Description

technical field [0001] The invention relates to the field of gelling materials, in particular to an alkali-activated composite gelling material and a preparation method thereof. Background technique [0002] Alkali-activated gelling materials are a kind of gelling materials formed by the reaction of volcanic ash active or latent hydraulic raw materials and alkaline activators. Its invention expands the scope of hydraulic mineral gelling materials. The former Soviet Union carried out a lot of research in this area and developed alkali slag cement. Studies have found that compared with general-purpose Portland cement, alkali slag cement has the advantages of small water demand, low heat of hydration, high strength, and good durability, but it also has fatal shortcomings such as fast setting speed and large hardening shrinkage. its wide application. In the 1970s, French Davidovits developed a new type of alkali-activated metakaolin cementitious material with metakaolin as th...

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Problems solved by technology

[0003] Literature search disclosure: ① Yip et al. published an article "Carbonate mineral addition to metakaolin-based geopolymers" in the journal "Cement & Concrete Composites" in 2008, 30(10):979-985, indicating that the addition of metakaolin-based geopolymers About 20% of calcite or dolomite can increase its compressive strength, but it will lead to a large shrinkage of the test body in the initial 90d; ② Zhu Qiang et al. The article "Mechanical Properties and Microstructure of Dolomite Fly Ash-Based Geopolymers" was published in the Journal of Salt Science, showing that the addition of 10-25% dolomite powder helps to improve the early and late stages of geopolymers. Compressive strength, dolomite participates in the reaction in the geopolymer, the dissolved Ca and Mg combine with the geopolymer gel to form a dense calcium magnesium aluminum silicate gel, and a good interfacial bond between the dolomite-gel matrix And the micro-aggregate effect of dolomite micropowder, which jointly promote the development and improvement of the strength of geopolymers, but did not study the setting time and shrinkage properties; Barium chloride or barium nitrate is used as an agent to solve the rapid setting problem caused by the addition of slag in the alkali-activated carbonate-slag composite cementitious material, but the disclosed method is relatively complicated and has a long construction period, which is not conducive to the construction site Operation