This chapter describes experimentally, with some modeling ideas, the autogeneous shrinkage of concrete. Some means of ameliorating this ubiquitous phenomenon in high performance concrete are also discussed.
This section describes computer modelling and experimental studies of the influence of cement particle size distribution on the autogeneous properties (internal RH, strain, and stress) of cement pastes.
This section discusses experimental results on the use of various means of alleviating autogeneous shrinkage in low water:cement ratio concrete, using surface tension reducing admixtures, saturated light-weight aggregate, and a coarser silica fume.
(3e) Potential Applications of Shrinkage-Reducing Admixtures beyond Drying Shrinkage Reduction (D.P. Bentz, to be submitted to Concrete International (2005).)
The SLABS model for the simulation of curing concrete bridge decks was developed with new boundary condition formulations that can accurately account for a wide variety of atmospheric conditions, addressing limitations of previous studies. Equivalent ages, estimated from the temperature predictions of SLABS, can vary up to 40 h over the conditions simulated after 24 h of hydration. Depth variations of equivalent ages reach 15 h.
(4a) The Influence of the Atmosphere on Curing Concrete Temperatures and Maturity (Wojcik, Gary, S., Advances in Cement and Concrete. Engineering Conferences International Proceedings, Copper Mountain, CO, August 10-14, 2003, 491-500 (2003).)
Proportioning concrete with internal curing requires careful consideration of the water demand of the hydrating cement paste and the water readily available from the saturated lightweight aggregates. A preliminary methodology for this mixture proportioning in presented here.
(5c) Materials Science-Based Models in Support of Internal Water Curing (D.P. Bentz, E.A.B. Koenders, S. Mönnig, H.-W. Reinhardt, K. van Breugel, and G. Ye., to be published as part of a RILEM state-of-the-art report (2006).)
(5d) Four Dimensional X-Ray Microtomography Study of Water Movement During Internal Curing (D.P. Bentz, Submitted to Proceedings of RILEM Conference, August 2006)
The concept of internal curing can be extended from the delivery of curing water to the potential delivery of chemical admixtures, from the saturated lightweight fine aggregates to the hydrating cement paste, for example. A preliminary experimental validation of this concept is provided in this section.
(6) Capitalizing on Self-Desiccation for Autogenous Distribution of Chemical Admixtures in Concrete (D.P. Bentz, to be published in the Proceedings of the 4th International Seminar on Self-Desiccation and Its Importance in Concrete Technology (2005))
(1) M. Geiker, D.P. Bentz and O.M. Jensen, American Concrete Institute Special Publication 218, High Performance Structural Lightweight Concrete, John P. Ries and Thomas A. Holm, eds., pp. 143-154 (2004).
(2) D.P. Bentz, O.M. Jensen, K.K. Hansen, J.F. Olesen, H. Stang, and C.J. Haecker, J. Amer. Ceram. Soc. 84 (1), 125-139 (2001).
(3a) D.P. Bentz, M. Geiker, and O.M. Jensen, Self-Desiccation and Its Importance in Concrete Technology, Eds. B. Persson and G. Fagerlund, Lund Sweden, June (2002).
(3b) D.P. Bentz and O.M. Jensen, Cement and Concrete Composites 26 (6), 677-685 (2004).
(3c) K.A. Snyder and D.P. Bentz, Cement and Concrete Research 34 (11), 2045-2056 (2004).
(3d) D.P. Bentz and P.E. Stutzman, ACI Materials Journal 103 (5), 348-356 (2006).
(3e) D.P. Bentz, Concrete International 27 (10), 55-60 (2005).
(4a) G. Wojcik, Advances in Cement and Concrete, Proceedings of the Engineering Conferences International, Copper Mountain, CO, August 10-14, 2003, 491-500 (2003).
(4b) D.P. Bentz, National Institute of Standards and Technology Internal Report 6551 August (2000).
(5a) D.P. Bentz, P. Lura, J. Roberts, Concrete International 27 (2), 35-40 (2005).
(5b) D.P. Bentz and K.A. Snyder, Cement and Concrete Research 29 (11), 1863-1867 (1999).
(5c) D.P. Bentz, E.A.B. Koenders, S. Mönnig, H.−W. Reinhardt, K. van Breugel, and G. Ye, to be published as part of a RILEM state-of-the-art report (2007).
(5d) D.P. Bentz, P.M. Halleck, A.S. Grader, and J.W. Roberts, Proceedings of the International RILEM Conference: Volume Changes of Hardening Concrete: Testing and Mitigation, Eds. O.M. Jensen, P. Lura, and K. Kovler, RILEM Publications S.A.R.L., 2006, pp. 11-20.
(6) D.P. Bentz, Proceedings of the 4th International Seminar on Self-Desiccation and Its Importance in Concrete Technology, Eds. B. Persson, D. Bentz, and L.-O. Nilsson, Lund University (2005) pp. 189-196.