TY - CONF A1 - Govin, Alexandre A1 - Schmidt, Wolfram A1 - Bartholin, M. C. A1 - Grosseau, P. A2 - Amziane, Sofiane A2 - Sonebi, Mohammed A2 - Charlet, Karine T1 - Effect of Guar gum derivatives combined with superplasticizers on properties of Portland cement pastes T2 - RILEM Proceedings PRO 119 N2 - Chemical admixtures allow to create a variety of fresh and hardened state properties in cementitious materials. In the case of self-compacting concrete, plasticizers or superplasticizers are introduced with the aim to decrease the yield stress and the viscosity of the materials. However, in order to prevent segregation and bleeding, and to improve the water retention of cement-based system, stabilizing agents or viscosity agents are often introduced in addition. Among these admixtures, polysaccharides are most commonly used. The aim of this study is to provide an understanding of competitive or synergetic effects induced by the combination of hydroxypropyl guar stabilizing agents (HPG) and superplasticizers on cement pastes. Two polycarboxylate superplasticizers (PCE) exhibiting different charge densities and one HPG were studied. It was found that the combination of HPG with PCE superplasticizer strongly affects the rheological behavior of cement pastes. Despite the presence of HPG, the viscosity of the pastes strongly decreased with increasing dosage of PCE until it became close to the viscosity of a cement paste with PCE only. However, the use of HPG in combination with PCE allows maintaining a significant yield stress in the cement paste compared to PCE alone. The increase in the charge density of the PCE seemed to amplify the drop of the viscosity and to reduce the gain on the yield stress induced by HPG. The results also highlight a delay in the setting-time of the cement paste by adding HPG and PCE. The delay induced by HPG is significantly lower than that generated by PCEs. However, the combination of the both kind of admixtures leads to a slightly shorter setting-time compared to the PCE alone. PB - RILEM Publications S.A.R.L. CY - Paris, France T2 - Second International RILEM Conference on Bio-based Building Materials, 21-23 June 2017 CY - Clermont-Ferrand, France DA - 21.06.2017 KW - Rheology KW - Cement KW - Guar Gum KW - Polysaccharide KW - Superplasticizer PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/43547 AN - OPUS4-43547 SN - 978-2-35158-192-6 SP - 55 EP - 61 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany