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蒸养石灰-粉煤灰混凝土是一种在上海广泛应用的墙体材料,这种混凝土经碳化后,其强度一般均有所下降。本文用XRD、DTA、IRS、EPMA及压汞测孔等分析手段,对比分析了这种混凝土与普通水泥混凝土的水泥石结构。结果表明,石灰-粉煤灰混凝土抗碳化性能较差的主要原因是其水化生成物碱度较低、水泥石孔隙率较高。选用细度高、标准稠度需水量低的粉煤灰,适当提高石灰及石膏掺量、降低用水量,可明显提高石灰-粉煤灰混凝土的抗碳化性能。
Steamed lime-fly ash concrete is a kind of wall material widely used in Shanghai. After the concrete is carbonized, its strength generally decreases. This article uses XRD, DTA, IRS, EPMA and mercury porosimetry to analyze the cement stone structure of this concrete and ordinary cement concrete. The results show that the main reason for the poor anti-carbonization performance of lime-fly ash concrete is the lower alkalinity of the hydration products and the higher porosity of the cement. The use of fly ash with high fineness and low water content of standard consistency, appropriate increase of lime and gypsum content, and reduction of water consumption can significantly improve the anti-carbonation performance of lime-fly ash concrete.