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Rheology, setting and hydration of calcined clay blended cements in interaction with PCE-based superplasticisers
Magazine of Concrete Research ( IF 2.7 ) Pub Date : 2021-01-04 , DOI: 10.1680/jmacr.19.00488
Ricarda Sposito 1 , Nancy Beuntner 2 , Karl-Christian Thienel 3
Affiliation  

Calcined clays represent a promising supplementary cementitious material (SCM) to face the growing demand for binders and to compensate for the decreasing availability of established SCMs worldwide. A fundamental knowledge about the interaction of cementitious systems with polycarboxylate ether (PCE)-based superplasticisers is required for their optimised use as clinker substitute. As clays contain different phyllosilicates, this study focuses on the behaviour of calcined phyllosilicates (metakaolin, metamuscovite, metaillite) and one calcined naturally occurring clay. The impact on the rheology, hydration and setting behaviour of blended cement pastes with two PCE-based superplasticisers is investigated using rotational viscometry, isothermal calorimetry and ultrasound, respectively. The investigations reveal a good dispersion effectiveness of both PCE-based superplasticisers even with challenging calcined phyllosilicates. The demand for superplasticiser can be derived largely from the physical properties of calcined materials, except for metamuscovite. The calcined naturally occurring clay is easily dispersed due to its high quartz content. The physical properties are also key parameters for the hydration and setting: the high specific surface area and pozzolanic properties of calcined phyllosilicates can compensate for retardation effects whereas there can be a significant retardation due to superplasticiser overdosage. Calcined clays with quartz may represent a promising future clinker substitute for the concrete industry in view of hitherto uncritical superplasticiser dosages.

中文翻译:

与基于 PCE 的减水剂相互作用的煅烧粘土混合水泥的流变学、凝结和水化

煅烧粘土代表了一种很有前途的补充胶结材料 (SCM),可以应对对粘合剂不断增长的需求,并弥补全球现有 SCM 可用性的下降。胶凝体系与聚羧酸醚 (PCE) 基超塑化剂相互作用的基本知识是它们作为熟料替代品的优化使用所必需的。由于粘土含有不同的页硅酸盐,本研究重点研究煅烧的页硅酸盐(偏高岭土、偏白云母、金属长石)和一种煅烧的天然粘土的行为。分别使用旋转粘度测定法、等温量热法和超声法研究了含有两种基于 PCE 的减水剂的混合水泥浆对流变学、水化和凝结行为的影响。研究表明,即使使用具有挑战性的煅烧页硅酸盐,两种基于 PCE 的超塑化剂也具有良好的分散效果。对超塑化剂的需求主要来自煅烧材料的物理特性,但偏白云母除外。由于石英含量高,煅烧的天然粘土很容易分散。物理性质也是水合和凝固的关键参数:煅烧的页硅酸盐的高比表面积和火山灰性质可以补偿阻滞效应,而由于超增塑剂过量使用可能会导致显着阻滞。鉴于迄今为止不严格的超塑化剂剂量,含石英的煅烧粘土可能代表未来混凝土工业的有前途的熟料替代品。
更新日期:2021-01-04
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