Discipline: Technology and Engineering
Subcategory: Materials Science
Miguel A. González - University of Puerto Rico Mayagüez
Co-Author(s): Oscar Marcelo Suárez, Hildélix Soto, Carlos Medina, Raul E. Marrero, Marivette Rullan, Andres Matos, Fernando Benitez, Silvia T. Esteves, Maria Sepulveda, University of Puerto Rico Mayagüez, Mayagüez, PR
Over the years numerous studies have proven that Portland cement (PC), the most employed construction material, is one of the prime air pollutants in the world. To reduce this noxious effect, numerous materials are being studied as partial substitutes for PC. Alas, the PC consumption reduction effects a degradation in its mechanical properties. Thus, PC partial substitutes that help retain or even enhance those mechanical properties are fly ash (FA), a widely used recycled cementitious material, and nanostructured SiO2 (ns) particles, which are proven to have pozzolanic and filler effects when incorporated in the mix. This research studies the interaction between both additives to produce a high performance concrete. Five different concrete mix designs, one being a control mix (traditional mix), were tested, according the appropriate ASTM standards. The performed experiments ranged from density assessment, absorption measurement, and void volume tests (ASTM C192) to compressive strength (ASTM C39), and tensile splitting tests (ASTM C496). The results demonstrated that the mixes containing FA and nS displayed a lower density and up to a 40% increment of high compressive resistance at an earlier age when compared to the control mix. A reduction in permeable pore spaces and absorption was also observed in the specimens containing both FA and nS for longer aging times. While the FA is effective as a cementitious replacement for Type I PC, nS particles helped retain the material strength and even raised it for early curing ages. Further studies will seek to enhance even more those mechanical properties with the implementation of natural, innovative and eco-friendly materials, such as bamboo fibers, with the goal of making the concrete industry environmentally friendlier.
References: American Society for Testing Materials (ASTM) (2015). Standard Test Method for Making and Curing Concrete Test Specimens in the Laboratory (C192 / C192M – 15). American Society for Testing Materials (ASTM) (2013). Standard Test Method for Density, Absorption, and Voids in Hardened Concrete (C642 – 13). American Society for Testing Materials (ASTM) (2015). Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens (C39 / C39M – 15a). American Society for testing Materials (ASTM) (2011). Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens (C496 / C496M- 11).
Funder Acknowledgement(s): This material is based upon work supported by the National Science Foundation under Grant No. 1345156 (CREST Program).
Faculty Advisor: Oscar Marcelo Suárez, email@example.com