Influence of clays on the rheology of cement pastes.pdf

Cement and Concrete Research 40 (2010) 384–391 Contents lists available at ScienceDirect Cement and Concrete Research j ourna l homepage: ht tp: / /ees.e lsev ie /CEMCON/defau l t .aspInfluence of clays on the rheology of cement pastes Nathan A. Tregger ?, Margaret E. Pakula, Surendra P. Shah Northwestern University, Civil and Environmental Engineering, 2145 Sheridan Road, Evanston, IL 60208, USA? Corresponding author. 2145 Sheridan Road, Suite A +1 847 491 7161. E-mail address: n.tregger@ (N.A. 0008-8846/$ – see front matter ? 2009 Elsevier Ltd. Al doi:10.1016/j.cemconres.2009.11.001a b s t r a c ta r t i c l e i n f oArticle history: Received 12 July 2008 Accepted 9 November 2009 Keywords: Clay Fresh concrete Rheology Cement paste FlocculationThe fresh state of concrete is becoming increasingly important in furthering the types of applications of todays constructionworld. Processing techniques have resulted in technologies such as self-consolidating concrete and depend on themicrostructural changes that take place during and immediately after mixing and placing. These changes to the microstructure reflect the flocculation behavior between the particles in suspension. The ability to modify this behavior allows control over the balance among flowability and shape-stability of concrete. This study investigates how clay admixtures affect the microstructure of cement pastes from a rheological stand point. Shear and compressive rheology techniques are used to measure how the solids volume fraction of suspensions with different admixtures evolves with stress. Based on these relationships, the effectiveness of clays on the balance between flowability and shape-stability is measured. Results are consistent with green strength tests performed on concrete mixes derived from the cement paste mixes.130, Evanston IL, 60208. Tel.: Tregger). l rights reserved.? 2009 Elsevier Ltd. All rights reserved.1. Introduction The fresh state of concrete is becoming increasingly important in