High Temperature Performance of Concrete Confinement by MWCNT Modified Epoxy Based Fiber Reinforced Composites

Abstract

The conventional method of fiber reinforced polymer (FRP) wrapping around concrete columns uses epoxy as the binder along with synthetic or natural fibers such as carbon, glass, basalt, jute, sisal etc. as the reinforcement. However, the thermal stability of epoxy is a major issue in application areas prone to fire exposure. The current work addressed this major drawback of epoxy by modifying it with a nanofiller, such as multiwalled carbon nanotubes (MWCNT), and reinforcing it using basalt and sisal fibers. The effect of exposure to elevated temperature on the behavior of concrete cylinders externally confined with these FRP systems was analyzed. Three types of specimens were considered: unconfined; confined with sisal fiber reinforced polymer (SFRP); and confined with hybrid sisal basalt fiber reinforced polymer (HSBFRP) specimens. The test samples were exposed to elevated temperature regimes of 100 °C, 200 °C, 300 °C and 400 °C for a period of 2 h. The compressive strengths of unconfined specimens were compared with various confined specimens, and from the test results, it was evident that the mechanical and thermal durability of the FRP systems was substantially enhanced by MWCNT incorporation. The reduction in the compressive strength of the FRP-confined specimens varied depending on the type of the confinement. After two hours of exposure at 400 °C, the compressive strength corresponding to the epoxy–HSBFRP-confined specimens were improved by 15%, whereas a 50% increase in strength corresponding to MWCNT-incorporated epoxy–HSBFRP-confined specimens was observed with respect to unconfined unexposed specimens. The MWCNT-modified epoxy-incorporated FRP-confined systems demonstrated superior performance even at elevated temperatures in comparison to unconfined specimens at ambient temperatures.

Durability and Accelerated Ageing of Natural Fibers in Concrete as a Sustainable Construction Material

“…It was evident that NaOH caused more severe damage to the cellulosic fibers and thus caused reduction in tenacity compared to treatment with Ca(OH) 2. These observations were consistent with previous results [68][69][70]. Basalt fibers showed excellent alkali resistance, maintaining almost all of their tenacity.…”

“…In several cases, sisal fibers showed a slight increase in mechanical properties as the fibers underwent the fibrillation process. Fibrillation is a process in which fibers develop a hairy appearance [67,68].…”

Evaluation of Hybrid Fiber Multiscale Polymer Composites for Structural Confinement under Cyclic Axial Compressive Loading

“…Joseph et al [39] explored the performance of nano filler modified epoxy-based FRP confinement under monolithic axial compression and found that the newly developed FRP confinement could improve the strength properties considerably. The high temperature performance of these confinements was also found to be superior [40].…”

Experimental analysis on light weight concrete utilizing compost and Ground Granulated Blast Furnace Slag (GGBS): Insights into elevated temperature properties through TGA

“…TGA is done on concrete columns with Fiber Reinforced Polymer (FRP) and they were exposed to elevated temperatures of up to 400 8C to know the decomposition of epoxy. It is observed that the epoxy starts to decompose at 342 8C [12]. In self-compacting concrete, LaSrCoO 3 oxides are added at 2% and when they are exposed to elevated temperatures of about 900 8C, the loss in mass is found to be less than the control specimen without LaSrCoO 3 oxides in it [13].…”