The cement-free binding material, namely geopolymer, is a novel binding material made from solid waste such as fly ash and slag activated by the alkali. In this research, orthogonal tests were carried out on 20 x 20 x 20mm cube paste specimens cured at room temperature to explore the rules of influence factors according to the compressive strength for 3d, 7d and 28d. The results revealed that the ratio of fly ash/slag is the most significant factor, the ratio of water/ (fly ash+ slag), the modulus of alkali activator and the dosage of desulfurized gypsum also play great role in strength development of the binder. The compressive strength of the specimens can be obtained to 65.0 MPa and 51.21MPa at maximum for 28d when the ratios of fly ash/slag are 30/70 and 40/60 respectively.
According to the demanded functions, a novel hardening accelerating and water reducing admixture has been excogitated which is based on a polycarboxylate superplasticizer and cooperated with some other hardening accelerants at the same time, and has many merits such as chloride free、sulfate free、low total alkali content、low dosage、high water reducing rate、high early strength and so on. The performance of this admixture has proved to be outstanding especially in accelerating the early strength of 12 hours and 24 hours age in the concrete tests.
Kinetic analysis of silicon carbide prepared by carbon-thermal reduction is introduced in this paper. Through the dynamic analysis, kinetic parameters of Si-C are calculated, and it is estimated that the time required reaction materials of different diameter completely converted to SiC at different temperatures. Reaction time is nearly 1 hour long when the reaction particle diameter is 1μm around 1900K.
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