复合磷铝酸盐-硅酸盐水泥的早期水化行为

Study on the Early Hydration Behaviors of Phosphoaluminate Portland Composite Cement

主要研究了复合磷铝酸盐-硅酸盐熟水泥新拌和硬化浆体早期水化行为以及外加剂(N B)掺量对相应参数的影响,并与52.5级硅酸盐水泥浆体的相应行为进行了比较。测定了外加剂(N B)掺量对净浆和砂浆1d和3d强度,分析了新拌和硬化磨细浆体悬浮溶液的pH值、ζ电位和离子电导(K);并运用分光光度法和比尔定律研究了浆体中犤C a2+犦和犤A lO4犦5-溶出浓度的规律同时用X R D半定量分析了浆体早期的水化程度。硬化浆体粉末悬浮液的ζ电位、离子电导(K),犤C a2+犦和犤A lO4犦5-离子的溶出浓度的研究结果综合表明:外加剂掺量为水泥的0.15%～0.21%范围内时各早期水化行为呈现出最佳值:复合水泥浆体1d,3d和7d中A lite的水化程度较硅酸盐水泥浆体相应龄期分别提高了35%,33%和49%;净浆和砂浆1d抗压强度较同龄期硅酸盐水泥浆体分别增长了3%～15%和10%～17%;3天净浆强度增长了9%～19%;与此同时,浆体溶液的pH值维持在11.6～11.75;与此同时,复合浆体的凝结时间随外加剂掺量有所增长,但仍在国标范围内,而且终凝时间较PC短。复合水泥新拌浆体悬浮液的犤C a2+犦的比浓度和溶液离子电导分析表明:复合水泥诱导期出现的时间较PC的缩短了1倍,并且加速期较PC约提早2h出现;而且诱导期和加速期之间,溶液中犤C a2+犦浓度差明显小于PC的。这?

The early hydration behaviors of phosphoaluminate Portland composite cement and the influences of additives on these behaviors were studied here.The comparison was conducted between composite cement and grade 52.5 Portland cement(abbreviation PC)which is corresponding to ASTM type I.The semi quantitative XRD has been employed to estimate the hydration degree of cement pastes.The dependences of pH values,ζpotential,ion conductivity (K) and the concentrations of [Ca2+] and [AlO4]5-of suspension solution of the composite hardened pastes on the additions of additive and on the hydration time were determined. The results reveal that in the addition range of 0.15～0.21wt/%additive,the pH value of the solution is 11.60～11.75,which implies the stable hydration environment of the composite cement; that the 1-day compressive strength of mortar and paste are 3%～15%and 10%～17%respectively higher than that of PC, which are consistency with the low values of ζpotential, K values and the concentrations of ions [Ca2+]and [AlO4]5-of suspension solution of the composite hardened pastes. The initial and final setting time for the paste with 0.18wt/%additive is 65 minutes and 115 minutes respectively. The analysis of specific concentration of [Ca2+],pH values and ion conductivity for the fresh cement suspension indicate that the occurrence of induction period for composite cement is one time earlier than that of PC and the occurrence of acceleration is 2 hours earlier than that of PC, which suggests that the active energy required for the presence of acceleration is lower than that of PC, and the presence of large size groups of [AlO4]5-and [PO4]3-modifies the transition rate and is favorite the formation of hydrates taking place between groups of Ca2+, OH-,[AlO4]5-and [PO4]3-.