H. Chen, M. Wyrzykowski, K. Scrivener, P. Lura, Prediction of self-desiccation in low water-to-cement ratio pastes based on pore structure evolution, Cem. Concr. Res., 49 (2013) 38-47. http://dx.doi.org/10.1016/j.cemconres.2013.03.013 1 PREDICTION OF SELF-DESICCATION IN LOW WATER-TO-CEMENT RATIO PASTES BASED ON PORE STRUCTURE EVOLUTION Hui Chen (1), Mateusz Wyrzykowski (2,3), Karen Scrivener (1), and Pietro Lura (2,4) (1) Laboratory of Construction Materials, École Polytechnique Fédérale de Lausanne, Switzerland (2) Empa - Swiss Federal Laboratories for Materials Science and Technology, Switzerland (3) Department of Building Physics and Building Materials, Lodz University of Technology, Poland (4) Institute for Building Materials, ETH Zurich, Switzerland Abstract High-performance concrete is sensitive to early-age cracking, mainly due to its rapidly- developing autogenous shrinkage. Autogenous shrinkage and internal relative humidity (RH) decrease are direct consequences of emptying of capillary pores due to cement hydration in low water-to-cement ratio concretes. To predict early-age cracking, it is desirable to model the evolution of the internal RH, and the accompanying autogenous shrinkage, based on the microstructure evolution. In this paper, the pore size distribution of cement pastes measured by mercury intrusion porosimetry and the chemical shrinkage are used as input data for calculating the internal RH of Portland cement pastes with different water-to-cement ratios (0.30, 0.35 and 0.40). The composition of the extracted pore solution is also taken into account. The measured RH can be predicted with good accuracy (mostly within 1-2% RH). However, a number of sources of error both in the experiments and in the analysis need to be identified and controlled. Keywords: Cement; Humidity; Hydration; Mercury Porosimetry; Microstructure;