Research Of Cement-based Cementitious Materials Thaumasite Formation Impact

In this paper, chemical thermodynamics and kinetic theory, analysis the Thaumasite the formation of the reaction conditions and the impact factors. The formation reaction affect different admixtures Thaumasite. Last by admixture added explore inhibiting Thaumasite sulfate attack in cementitious systems. Studies have shown that:l.By thermodynamic calculations illustrate, ettringite shift mechanism at0℃to20℃can be spontaneous in20℃, and the solution transition mechanism can not be spontaneous. By thermodynamic calculations show that the same temperature ettringite transition mechanism of reaction trend is greater than the solution shift mechanism.2. Aluminum-containing accelerator Add to greatly accelerate the Thaumasite formation reaction rate, wherein the aluminum phase Al3+in the presence of higher activity the reaction, the reaction rate is faster. The aluminum forming reaction carried by ettringite shift mechanism Thaumasite.3. Ethers and lipids Polycarboxylate slowing to some extent Thaumasite formation, its mechanism is that the Polycarboxylate the Add, change the Zeta potential of the solution, so that the particles in the solution to obtain a good dispersion4. The early strength agent triethanolamine and triisopropanolamine Add to a certain extent slow down the Thaumasite formation.5. The limestone powder based cementitious material mixed with a certain degree of potassium oxalate delay Thaumasite form, but can not inhibit Thaumasite formed, with increased dosage of potassium oxalate.6. Barium hydroxide is incorporated in the limestone powder based cementitious materials can effectively inhibit the formation of Thaumasite Add barium hydroxide.7. Incorporated in the limestone powder based cementitious materials. Sodium polyphosphate can effectively inhibit the Thaumasite formation of sodium polyphosphate with strong crystallization inhibition.8. In limestone powder yl gelling materials incorporated sodium tartrate to some extent inhibit the formation of Thaumasite, sodium tartrate is a chelating agent.9. Based cementitious materials in the limestone powder mixed with borax to a certain extent delay Thaumasite form, but can not suppress Thaumasite formation increased with the dosage of borax, the more significant the delay formation of Thaumasite effect. Late formation of the solid solution, Thaumasite-Ettringite produce Thaumasite sulfate corrosion.10. In limestone powder yl gelling materials incorporated amino acid NH compound to some extent inhibit the formation of Thaumasite...