Effectiveness of PCE superplasticizers in calcined clay blended cements

Journal Article · Mon Mar 15 04:00:00 EDT 2021 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2020.106334· OSTI ID:23206366

Li, Ran; Lei, Lei ^[1]; Sui, Tongbo ^[2]; Plank, Johann ^[1]

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1. Technische Universität Müncheen, Chair for Construction Chemistry, 85747 Garching, Lichtenbergstraße 4 (Germany)
2. Sinoma Research Institute, Sinoma International Engineering Co., Ltd, No. 16 Wangjing North Road, Chaoyang District, Beijing 100102 (China)

Highlights: • Cements containing 0–40 wt% of a calcined clay rich in meta kaolin were studied. • The calcined clay decreases fluidity of the blended cements considerably. • In cement, the calcined clay adsorbs a large amount of Ca{sup 2+} ions. • A common HPEG polycarboxylate superplasticizer fluidizes OPC/CC blends best. • A zwitterionic PCE also fluidizes well and adsorbs in similar amounts as HPEG. The impact of a calcined clay (CC) rich in meta kaolin (~50 wt%) present in composite cements at 0–40% substitution rate for the clinker was studied relative to the dispersing force of different PCE superplasticizers. It was found that CC increases the water demand of the blended cements considerably (+85% for the 60:40 blend vs. neat OPC). Furthermore, PCEs which fluidize OPC best also provide optimal performance in CC blended cements, but require much higher dosages (in OPC/CC 60:40, 4–6 times as compared to neat OPC). In all systems, HPEG-PCE produced superior dispersing performance over anionic MPEG-PCEs. A mechanistic study involving zeta potential measurements revealed that the initially negatively charged calcined clay surface adsorbs huge amounts of Ca{sup 2+} ions from the pore solution, thus facilitating adsorption of anionic PCE superplasticizers. The results signify that commercially available PCE products can effectively fluidize OPC/CC blended cements.

• OSTI ID: 23206366
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 141; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
CALCIUM IONS
CEMENTS
COMPARATIVE EVALUATIONS
PLASTICIZERS
SURFACES
WATER REQUIREMENTS
ZWITTERIONIC COMPOUNDS