A Study on Durability and Microstructural Analysis for Macro Synthetic Fiber Reinforced Concrete with Supplementary Cementitious Materials

Background: Thermal cracking, delayed ettringite production and low tensile strength are three significant problems for high-strength concrete. Objectives: The current experimental study aims to determine the durability characteristics of concrete for application in pavements. To test how well the M40 grade of concrete absorbed chloride and water, the amounts of Supplementary Cementitious Materials (SCM) like Granulated Blast-Furnace Slag (GBFS) and fixed amounts of Fly Ash (FA) and Macro Synthetic Fiber (MSF) were optimized. Methods: One sample (S1) was made entirely of Ordinary Portland Cement (OPC) and five samples (S2, S3, S4, S5, and S6) made simply of SCMs, in which OPC was substituted with 20% FA+20% GBFS+1.5% MSF, 20% FA+25% GBFS+1.5% MSF, 20% FA+30% GBFS+1.5% MSF, 20% FA+35% GBFS+1.5% MSF, and 20% FA+40% GBFS+1.5% MSF, respectively, were cast in standard blocks with a volume of one cubic meter for this purpose. Field Emission Scanning Electron Microscopy (FESEM), Fourier-Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) investigations are used to examine the number of hydration products created at 28 days, which differ for different percentages of SCMs. Findings: Furthermore, 501, 520, 535, 565, and 590 coulombs are the measured Rapid Chloride Permeability Test (RCPT) values for the S2 to S6 samples. Similarly, the S1 sample is projected to have more than 2600 coulombs, showing a better endurance of samples based on SCMs. The microstructural characterization findings (i.e., XRD, FTIR and FESEM) suggested that GBFS and FA are promising SCMs for enhancing the strength and durability properties of the mix. Novelty and applications: This study validates the viability of using GBFS, FA, and MSF in pavement applications, yielding noteworthy environmental advantages and lowering dependency on OPC. Keywords: Durability, Microstructural investigation, Macro synthetic fiber, Fly ash, Granulated blast furnace slag, Pavements