加碱低温煅烧玻屑凝灰岩制备无熟料水泥

加碱低温煅烧玻屑凝灰岩制备无熟料水泥,初步优化了制备工艺并通过SEM和XRD分析探讨了胶凝机理。通过在该凝灰岩中掺加烧碱或纯碱低温煅烧,然后掺入占煅烧料15%的Ca(OH)2和30%的Ca SO4·2H2O,制得具有适当强度且抗水性良好的无熟料水泥。石膏的加入能有效提高水泥强度,加碱可降低煅烧温度,从无碱煅烧时的700℃降低至加碱煅烧时的300℃并提高胶凝活性,烧碱比纯碱更为有效。随着Na OH增加至凝灰岩的8%,水泥抗压强度增加至基本稳定。SEM与XRD分析均表明,水泥水化时并未生成结晶水化物。

Synthesizing Clinker-free Cements through Calcining the Vitric Tuff with Alkali at Low Temperature

Clinker-free cements were synthesized through calcining the virtric tuff with alkali at low temperature, and the techniques were primitively optimized and the related cementing mechanisms were discussed through SEM and XRD analyses. Adding NaOH or Na2CO3, the tuff were calcined to get precursors, then by mixing the cooled precursors powders with optimal contents of Ca(OH)215% and CaSO4·2H2O 30%, the cements were prepared and obtained reasonable compressive strengths with fine water resistances. The additive of gypsum can obviously improve the impressive strengths of the cements. The alkali reduced the calcination temperature of the tuff from 700℃ without alkali additives to 300℃ with alkali, and NaOH is proved to be more effective than Na2CO3. The compressive strength improves according to the content of NaOH and becomes grossly stable with the NaOH content 8% of the tuff. The SEM and XRD analyses indicated that there is no hydrous crystal phase appearing during hydration of the clinker-free cements.