复配早强型聚羧酸减水剂对蒸养混凝土性能影响研究

发布时间：2018-03-12 19:48

  本文选题：复配　切入点：早强　出处：《西安建筑科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：聚羧酸高性能减水剂作为第三代高性能减水剂,具有掺量低、减水率高、保坍性能好、有害物质含量极低等综合技术性能,但聚羧酸减水剂的独特分子结构特点会延缓水泥水化,影响混凝土早期强度发展,限制了在预制构件等工程中的应用,采用复配的方法制备早强性能的聚羧酸减水剂,具有工艺简单,易于控制的特点。本文将有机盐、无机盐等早强剂与阴离子型聚羧酸减水剂(PC-O)和两性型聚羧酸减水剂(PC-E)分别进行复配,探究不同类型和不同掺量早强剂与两种聚羧酸减水剂复配对胶砂及混凝土性能的影响。试验不仅对其标养和蒸养条件下的性能进行研究,还采用直接测温法和XRD技术研究了蒸养条件下不同早强剂与聚羧酸减水剂复配对水泥水化温峰值、温峰出现时间及Ca(OH)2生成量的影响规律,对复配早强型聚羧酸减水剂的作用机理进行了分析,论文主要研究内容及结果如下:首先,对阴离子型和两性型聚羧酸减水剂的性能进行对比,对比两种聚羧酸减水剂不同掺量对流动性能、凝结时间和胶砂强度的影响规律,确定最佳复配掺量。结果表明:当阴离子型聚羧酸减水剂的掺量为0.34%和两性型聚羧酸减水剂掺量为0.36%时,两组水泥净浆既有较好的流动度又有较小的经时损失,而且初凝、终凝时间较短,胶砂1d抗压强度也达到最大值。其次,使用早强剂(TEA、Li_2CO_3、Na_2SO_4)与PC-O进行复配,对比不同掺量早强剂与PC-O复配对标养和蒸养胶砂,蒸养混凝土强度的影响。结果表明:在标养条件下,复配早强型聚羧酸减水剂对胶砂早期强度的提高并没有明显效果,在80℃蒸养条件下,TEA掺量为0.06%、Li_2CO_3为0.06%、Na_2SO_4为0.6%时均有明显早强效果。然后,使用早强剂(Na_2SO_4、NaNO_2、C_(16)H_(34)O)与PC-E进行复配,结果表明:在标养和50℃、80℃蒸养条件下,Na_2SO_4复配掺量为0.6%~0.8%、NaNO_2为0.6%~0.8%、C_(16)H_(34)O为0.03%~0.05%时,不仅早强效果显著,而且后期强度也有明显增强。特别是在80℃蒸养条件下,早期强度增强更为明显,其顺序为C_(16)H_(34)ONa_2SO_4NaNO_2。最后,通过对掺入早强剂与两种不同品种聚羧酸减水剂复配净浆温度-时间曲线和水泥石XRD的分析可知,复配两性型聚羧酸减水剂更能够提高水泥水化温升,缩短温峰出现的时间,生成更多的Ca(OH)2,以及促进了C3S的早期水化,生成较多的C-S-H。
[Abstract]:Polycarboxylic acid high performance water reducer, as the third generation high performance water reducing agent, has comprehensive technical properties, such as low content, high water reducing rate, good collapsibility, very low content of harmful substances, etc. However, the unique molecular structure of polycarboxylic acid superplasticizer will delay cement hydration, affect the early strength development of concrete, and restrict the application in prefabricated components. In this paper, organic salts and inorganic salts were mixed with anionic polycarboxylic acid superplasticizer (PC-O) and amphoteric polycarboxylic acid superplasticizer (PC-E) respectively. The effects of different types and different contents of early strength agents and two kinds of polycarboxylic acid water reducer on the properties of cement sand and concrete were studied. The effects of different early strength agents and polycarboxylic acid superplasticizer on cement hydration temperature peak value, temperature peak time and Ca(OH)2 production were also studied by direct temperature measurement and XRD technique. In this paper, the mechanism of the compound early and strong polycarboxylic acid superplasticizer is analyzed. The main research contents and results are as follows: firstly, the performance of anionic polycarboxylic acid superplasticizer and amphoteric polycarboxylic acid superplasticizer is compared. The effects of two kinds of polycarboxylic acid superplasticizer on fluidity, setting time and cement sand strength were compared. The results show that when the amount of anionic polycarboxylic acid superplasticizer and amphoteric polycarboxylic acid superplasticizer is 0.34% and 0.36 respectively, the two groups of cement paste have both better fluidity and smaller meridional loss, and the initial setting is the same as that of anion polycarboxylic acid superplasticizer and amphoteric polycarboxylic acid superplasticizer. The final setting time was shorter, and the compressive strength of cement sand reached its maximum value in 1d. Secondly, PC-O was mixed with PC-O by using the early strength agent TEAS Li2COS3 / Na2SO4. The results show that under the standard condition, the composite of early strength polycarboxylic acid superplasticizer has no obvious effect on the early strength of cement sand. Under the condition of 80 鈩，

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