Durability and Microstructure Properties of Concrete with Arabic Gum Biopolymer Admixture

Abstract

Arabic gum biopolymer (AGB) has recently been demonstrated to improve mechanical and physical properties of fresh and hardened concrete which makes it a promising sustainable and environmentally friendly water-reducing admixture. The present work focuses on the effect of added AGB on the workability, setting time, and durability of concrete. Furthermore, a microstructure analysis is conducted to provide objective evidence and support for previous findings and hypothetic interpretations. Flow table experiments are conducted on Portland cement mortar mixed with different percentages of AGB to evaluate the workability. The initial setting time of cement paste is measured for different AGB contents. X-ray fluorescence tests are performed on cement-AGB mix powder to determine its chemical composition. Carbonation depth in AGB concrete samples is estimated to assess durability. AGB-added cement powder was subjected to X-ray diffraction and SEM tests to determine the rate of hydration and to expose the microstructure properties of AGB cement mix and help explain its macroscopic behavior, respectively.

Characterization of Gum Arabic in Concrete Mix Design

“…The result of slump tests is shown in Table (2) and graphically in Figure (5). Generally, it has been shown that slump increases with increasing GA ratios.…”

“…Also, it was observed that for concrete mixes containing 0.7% of GA dosage the cubes demolding required two days. (5) shows the average compressive strength of the concrete cubes taken at ages of 7, 28 and 91 days. There were large increases in strength when the dosages of GA and curing of samples were increased.…”

“…Previous studies have shown the effects of different types of gum Arabic in concrete mixes; such as: [5], presented a paper on Arabic gum biopolymer (AGB) focusing on the impact of added AGB on the setting time, durability of concrete, and workability. They further performed X-ray fluorescence tests on cement-AGB mix powder for determining its chemical structure for estimating carbonation depth in AGB concrete samples for evaluating durability.…”

Performance evaluation of compressed laterite blocks stabilised with cement and gum Arabic

“…This reduction in the percentage of water absorption obtained for blocks with GA is explained by the emulsifying property of GA which allows it to fill the voids in the cement microstructure, increase the density of the material and create bonds between different particles thus reducing the voids between the different particles [7,20,34,45]. In addition, [32]confirmed that GA is a stabilizer and waterproofing agent used in mud coatings.…”

“…It is probably because of this high density that these types of blocks showed the lowest percentage of water absorption at 28 days (3.8%) and the highest compressive strength at 28 days (4.23 MPa). This is because the reaction between cement and GA forms calcium silicate hydrate (C-S-H) that is denser and in greater quantity than the C-S-H obtained from cement alone, which further improves the material properties and leads to better performance [34,45]. Dry density results of laterite soil stabilised with GA without cement showed that dry density decreases with increasing GA content [22,50].…”