Impact of admixtures on the hydration kinetics of Portland cement J. Cheung a, ⁎, A. Jeknavorian a , L. Roberts b , D. Silva a a W.R. Grace, 62 Whittemore Avenue, Cambridge MA 02140, USA b Roberts Consulting Group LLC, 44 Windsor Avenue, Acton MA 01720, USA abstract article info Article history: Received 29 January 2010 Accepted 8 March 2011 Keywords: Admixture (D) Cement (D) High calcium fly ash (D) Hydration (D) Sulfate balance (D) Most concrete produced today includes either chemical additions to the cement, chemical admixtures in the concrete, or both. These chemicals alter a number of properties of cementitious systems, including hydration behavior, and it has been long understood by practitioners that these systems can differ widely in response to such chemicals. In this paper the impact on hydration of several classes of chemicals is reviewed with an emphasis on the current understanding of interactions with cement chemistry. These include setting retarders, accelerators, and water reducing dispersants. The ability of the chemicals to alter the aluminate–sulfate balance of cementitious systems is discussed with a focus on the impact on silicate hydration. As a key example of this complex interaction, unusual behavior sometimes observed in systems containing high calcium fly ash is highlighted. © 2011 Elsevier Ltd. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1290 2. Importance of sulfate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1290 3. Impact of retarders and accelerators on the hydration of Portland cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1292 3.1. Impact of retarders on the hydration of Portland cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1293 3.1.1. Impact of retarders on silicates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1293 3.1.2. Interaction of retarders with aluminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1294 3.1.3. Requirements for modeling the impact of retarders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1296 3.2. Impact of accelerators on the hydration of Portland cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1296 3.2.1. Impact of accelerators on silicates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1296 3.2.2. Interaction of accelerators with aluminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297 3.2.3. Impact of triethanolamine and triisopropanolamine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1298 3.2.4. Requirements for modeling the impact of accelerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1300 4. Impact of water reducers and superplasticizers on the hydration of Portland cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1300 4.1. Chemistries of the HRWRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 4.2. Interaction between water reducers/high range water reducers and sulfates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 4.2.1. Formation of organo mineral phases (OMPs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 4.2.2. Uptake of NSFC by C 3 A, C 4 AF and C 3 S as a function of interground sulfate . . . . . . . . . . . . . . . . . . . . . . . . . 1301 4.2.3. Effect of polymer structure on the sulfate-PCE competition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 4.3. Impact on the time of addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1302 4.4. Impact on addition rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1303 4.5. Requirements for modeling the impact of water reducing dispersant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1303 5. High calcium fly ash interactions as a modeling opportunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304 5.1. Normal impact of differing materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1305 5.2. Serious impact at higher high calcium fly ash dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1305 5.3. Extreme non-Arrhenius behavior with higher temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1306 5.4. Requirements for modeling the behavior of systems with high calcium fly ash . . . . . . . . . . . . . . . . . . . . . . . . . . . 1306 Cement and Concrete Research 41 (2011) 1289–1309 ⁎ Corresponding author. E-mail address: Josephine.H.Cheung@grace.com (J. Cheung). 0008-8846/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cemconres.2011.03.005 Contents lists available at ScienceDirect Cement and Concrete Research journal homepage: http://ees.elsevier.com/CEMCON/default.asp