Reinforcing cementitious structures by pH activated in-situ shrinking microfiber

Eric S. Kim; Patrick C. Lee; Dryver R. Huston

doi:10.1117/12.2261298

4 April 2017 Reinforcing cementitious structures by pH activated in-situ shrinking microfiber

Eric S. Kim, Patrick C. Lee, Dryver R. Huston

Proceedings Volume 10166, Industrial and Commercial Applications of Smart Structures Technologies 2017; 101660I (2017) https://doi.org/10.1117/12.2261298
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2017, Portland, Oregon, United States

Abstract

This paper describes an innovational fiber reinforcement technology for cementitious composite structures by using shrinking microfibers. Unlike incumbent passive reinforcing microfiber technology, in-situ shrinking microfibers that respond to an external stimulus such as heat, pH, or moisture variations can induce pre-compression to matrix and create additional resistance from external loads. In this paper, pH-activated shrinking (pHAS) microfibers and pH passive (pHP) microfibers made from chitosan powder were used to investigate the reinforcing effect of shrinking mechanism. The specimens reinforced by the range of 0 to 2 wt% of pHAS microfibers, pHP microfibers as well as control samples were prepared, and mechanical properties were compared with three-point bending tests and compression tests. For the three-point bending tests, the reinforcing effect from pHAS microfibers were shown in the specimens with 0.5 wt%, 133 % increase in maximum bending strength compared to the control specimens. However, in compression tests, significant strength increases were not shown, for several possible reasons: (i) weak bonding between fibers and matrix, (ii) small % elongation to break of chitosan microfibers, (iii) abrupt moisture content change in cementitious matrix due to chitosan microfibers, and (iv) micro-cracks due to shrinking related de-bonding which caused more damaging in compression tests than in three-point bending tests. To solve the problems, application of microfibers made from blending Poly(ethylene oxide) (PEO) and chitosan has been also studied.

Citation Download Citation

Eric S. Kim, Patrick C. Lee, and Dryver R. Huston "Reinforcing cementitious structures by pH activated in-situ shrinking microfiber", Proc. SPIE 10166, Industrial and Commercial Applications of Smart Structures Technologies 2017, 101660I (4 April 2017); https://doi.org/10.1117/12.2261298

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