Professor of Materials Science & Engineering and Professor of Civil & Environmental Engineering

BS, physics,
1969, Tufts University

PhD, materials science, 1975, Brown University

Contact Info
CV/bio/publications
Civil Engineering page

 

Materials science of cements

After 30 years of studying the variable and illusive microstructure of cement-based materials, Jennings has developed the first successful, fully quantitative models for both the microstructure and the nanostructure of calcium silicate hydrate (C-S-H), the major component of hydrated cement. The model was originally based on highly scattered and contradictory surface area and density data mostly published in the 1950’s and 60’s. The model has been further developed to form a basis for quantitatively predicting static properties, as measured for example by nanoindentation techniques, and linking these relationships to the design of new materials. Also the model is being extended to larger scales, greater than 100 nm. It accounts for observation obtained by sophisticated techniques - cutting edge electron microscopy and small angle neutron scattering - that reveal a specific complex fractal structure. New phase diagrams have been proposed that rationalize disparate data published by Jennings’ research group and by other workers during the last 50 years. In addition, our research has laid the foundation for solving the 100-year-old question about the mechanism that controls the rate of hydration of cement. Jennings has also developed an analogy between the structure of C-S-H and a gel or precipitate. This facilitates an interpretation of changes in the microstructure induced during drying, as well as opening the door to applying new research results to colloids in general.

Associations and Awards

Copeland Award, American Ceramic Society, 2004

Fellow and Chartered Engineer, Institute of Materials, United Kingdom

Fellow, The American Ceramic Society, 1993

Fellow and Chartered Engineer, Institute of Materials, United Kingdom, 1994

Professional Society Memberships

1992 - present American Concrete Institute
1992 - present American Society of Civil Engineers
1981 - present American Ceramic Society
1980 - present Institute of Materials, U.K.

Editorial Boards

Member, Advisory Board, Journal of Advanced Concrete Technology (2001 - present)

Member, Editorial Board, Cement and Concrete Research

Associate Editor, Journal of the American Ceramic Society

Publications

“A multi-technique investigation of the nanoporosity of cement paste,” (J.J. Thomas, H.M. Jennings, Julia S. Gevrenov, Georgios Constantinides, and Franz-Josef Ulm), Cement and Concrete Research, 37 329-336 (2007)

“Decalcification shrinkage of cement paste,” (Jeffrey Chen, J.J. Thomas, and H.M. Jennings), Cement and Concrete Research, 36 [5] 801-809 (2006)

“A Colloid Interpretation Of Chemical Aging Of The C-S-H Gel And Its Effects On The Properties Of Cement Paste,” (J.J. Thomas, H.M. Jennings) Cement and Concrete Research, 36 (1): 30-38 (2006)

“Effects of Decalcification on the Microstructure and Surface Area of Cement and Tricalcium Silicate Pastes,” (J.J. Chen, J.J. Thomas, H.M. Jennings, A.J. Allen) Cement and Concrete Research, 34 [12] 2297-2307 (2004).

“Comment on ‘The BET-Specific Surface Area of Hydrated Portland Cement and Related Materials’ by Ivan Odler,” (J.J. Thomas, H.M. Jennings) Cement and Concrete Research, 34, [10] 1959-1960 (2004).

"Solubility and structure of calcium silicate hydrate"  (Chen JJ, Thomas JJ, Taylor HFW, et al.) Cement and Concrete Research, 34 (9): 1499-1519 (2004)

Publications in PDF format.