Complex, time-dependent, and multi-scale interactions exist between the surrounding environment and the aging processes of cement-based composites. Over its lifetime, the material is subjected to combinations of coupled, physical, chemical, and mechanical degradation processes that lead to a breakdown of the matrix microstructure and the eventual weakening of the material integrity. A variety of environmental weathering forces (water, carbon dioxide, salts, and temperature changes) result in internal chemical changes that cause a build up of localized internal stresses due to expansion, shrinkage, and loss of cohesion of the paste. These stresses lead to material damage via initiation of micro-cracks, the propagation of macro-cracks, and the ultimate failure of the material.

Our group looks at the problem from an integrated approach that differs from conventional approaches by breaking the problem into its elementary components at different scales with an emphasis on the mechanisms and failure modes at the inclusion-cement interface.

We utilizes state-of-the-art experimental characterizations (mechanical, chemical, and physical) of weathering mechanisms across multiple length scales (nano to macro) in combination with computational and analytical analysis, including molecular dynamics simulations, to further elucidate the failure modes of inclusion–cement interfaces and micro-macroscale upscaling techniques.

Selected References

“Influence of carbon nanofiber clustering in cement pastes exposed to sulfate attack,” L. Brown, F. Sanchez. Construction and Building Materials, 166: 181-187, 2018.

“Use of nanoindentation phase characterization and homogenization to estimate the elastic modulus of heterogeneously decalcified cement pastes,” L. Brown, P.G. Allison, F. Sanchez. Materials & Design, 142: 308-318, 2018.

“Influence of carbon nanofiber clustering on the chemo-mechanical behavior of cement pastes,” L. Brown and F. Sanchez. Cement and Concrete Composites, 65: 101-109, 2016.

“A nanoindentation study of Portland cement pastes exposed to a decalcifying environment,” L. Brown and F. Sanchez. In: Sobolev, K. and Shah, S. (eds). Nanotechnology in Construction: Proceedings of the fifth International Symposium on Nanotechnology in Construction (NICOM5). Cham, Switzerland: Springer International Publishing (2015). p. 65-70. ISBN 978-3-319-17088-6.

“Performance of carbon nanofiber-cement composites subjected to accelerated decalcification,” L. Brown, F. Sanchez, D. Kosson and J. Arnold. European Physics Journal Web of Conferences, 56, 02005, 2013.

“Multi-scale performance of carbon microfiber reinforced cement-based composites exposed to a decalcifying environment,” F. Sanchez and A. Borwankar. Materials Science and Engineering: A, 527(13-14), 3151-3158, 2010. View Abstract.

“Multi-scale performance and durability of carbon nanofibers/cement composites,” F. Sanchez, L. Zhang, and C. Ince, In: Nanotechnology in Construction 3: Proceedings of the NICOM3, Springer Proceedings in Physics, Zdenek Bittnar (Editor), Peter J M Bartos (Editor), J. Zeman (Editor), Jiri Nemecek (Editor), V. Smilauer (Editor), 438p., 2009. View Abstract.

“Effect of decalcification on the performance of carbon microfiber reinforced cement-based materials,” F. Sanchez, A. Borwankar, and C. Ince. RILEM Proceedings Book related to the NUCPERF 2009 Workshop (Long Term Performance of Cementitious Barriers and Reinforced Concrete in Nuclear Power Plants and Waste Management (EFC Event n°317)). 30 March – 2 April 2009, Cadarache, France. e-ISBN 978-2-35158-087-5, 119-124, 2009. View Abstract.