Title: Strength and Crack Resistance of Carbon Microfiber Reinforced Concrete

Author(s): Michael Dopko, Meysam Najimi, Behrouz Shafei, Xuhao Wang, Peter Taylor, and Brent Phares

Publication: Materials Journal

Volume: 117

Issue: 2

Appears on pages(s): 11-23

Keywords: accelerating admixture; carbon microfiber; early-age strength; fiber-reinforced concrete; restrained shrinkage; shrinkage-reducing admixture

DOI: 10.14359/51720297

Date: 3/1/2020

Abstract:
This study investigated the effect of four volume dosages (that is, 0, 0.1, 0.3, and 0.5%) of high-elastic-modulus carbon microfiber, shrinkage-reducing admixture (SRA), and accelerating admixture (ACC) on the 24-hour compressive strength and restrained shrinkage of carbon microfiber-reinforced concrete. Additional 7- and 28-day compressive strength tests, as well as 1-, 7-, and 28-day splitting tensile strength tests, were carried out on the mixtures without and with 0.3% carbon microfiber. Results showed that, overall, increasing the carbon microfiber dosage increased the compressive strength, particularly at early ages. Splitting tensile strength results were used along with the restrained shrinkage ring results to quantify the restrained shrinkage cracking potential of the mixtures. It was found that carbon microfiber and SRA can both significantly reduce the drying shrinkage cracking potential of concrete. The combination of SRA and ACC in concrete provided compatible effects, characterized by increased early-age compressive strength, as well as reduced shrinkage and cracking potential.