水泥沥青浆体中减水剂与乳化沥青的竞争吸附行为

Adsorption behaviors of superplasticizer and emulsified asphalt in cement-asphalt mortar

摘要:

为揭示水泥沥青砂浆(CA砂浆)中水泥对乳化沥青和减水剂的吸附规律，采用微量热仪分析了减水剂、乳化沥青(单掺及同掺)对水泥水化诱导期的延迟作用.采用“固含法”研究了减水剂种类对水泥-乳化沥青经时吸附规律的影响，以及减水剂在不同添加顺序时对水泥-乳化沥青经时吸附规律的影响.采用偏光显微镜对减水剂作用下水泥-乳化沥青的吸附行为进行了原位观测.结果表明：CA砂浆中的乳化沥青和减水剂均能显著延迟水泥的水化诱导期，两者同掺使延迟作用产生了明显的协同效应；聚羧酸减水剂与乳化沥青对水泥的吸附作用存在明显的竞争关系，两者同掺时水泥优先吸附减水剂分子，减水剂耗尽后，水泥再吸附乳化沥青.减水剂后掺时可使部分吸附的乳化沥青发生解吸附.

Abstract:

To investigate the adsorption mechanism of cement on emulsified asphalt and superplasticizer in cement-asphalt mortar (CA mortar), the retardation effects of superplasticizer and emulsified asphalt on cement hydration were analyzed by the result of hydration heat measured by microcalorimetry. The effects of the type and adding sequence of superplasticizer on the adsorption of cement-emulsified asphalt were studied. In addition, the in-situ observation of the adsorption between cement and emulsified asphalt under the function of superplasticizer was conducted by using the polarizing microscope. Results showed that both emulsified asphalt and superplasticizer could retard the cement hydration and evidently extend the induction, while the co-adding of superplasticizer and emulsified asphalt resulted in evident synergistic effect in respect of the induction's extension. Competitive relationship obviously existed between the adsorption of polycarboxylate superplasticizer and emulsified asphalt on cement. In the case of coexistence of superplasticizer and emulsified asphalt, the cement was adsorbed by the former in priority. When the superplasticizer was added after emulsified asphalt, the adsorbed emulsified asphalt particles could be substituted by superplasticizer.