Engineering properties and durability of concrete with arabic gum biopolymer

Abstract

The use of materials of vegetal origin is increasingly being promoted in many industries due to their cost-effectiveness and the sensitivity to sustainability and environmental protection. Natural gum is a wild plant by-product that is mainly found in Sudan and is also growing in other African countries. It has long been used in different industries. However, its utilization is very limited in the building sector, although there appears to be a positive potential for the use of Arabic Gum Biopolymer (AGB) in the construction industry. Since most natural gum is produced in Sudan, this study focuses on a Sudanese product called AGB, which has improved the properties of the concrete. The main aim of this research is to evaluate the effect of Arabic Gum Biopolymer on the fresh, physical, mechanical and durability properties of ordinary concrete at different ages and to determine the optimum percentage of AGB that will improve the concrete properties. For this purpose, concrete specimens were designed to evaluate the effect of AGB as an additive to ordinary concrete. AGB was mixed with the water in proportions within the range from 0 to 1.2% of the weight of the water. Fresh concrete properties, physical and mechanical properties were examined in addition to durability properties and microstructural analysis of the concrete. The experimental results showed that initial setting time and workability of the AGB cement mixes increase with AGB content up to an optimal amount fraction of 0.9%. The density, air content and permeability properties gradually were reduced with increase in AGB fraction. The AGB concrete strength was found to exhibit a maximum improvement reaching about 8% for an AGB fraction between 0.7 and 0.9%. The carbonation depth, acid resistance, chloride penetration depth and fire resistance decrease by 11%, 10%, 20 % and 12% respectively, for AGB percentage of 0.9%. X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) shows the presence of AGB chemical components in the AGB-added cement. X-ray diffraction (XRD) and Fourier Transformed Infrared Spectrometer (FTIR) analysis results reveal virtually similar hydration pattern of AGB concrete relative to the ordinary Portland cement (OPC) concrete. The scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area analysis, for AGB concrete specimen present fewer voids dispersed in the microstructure of the AGB mixes. This explains the improvement observed in the durability and microstructural properties of the ordinary concrete mixes as a result of AGB addition. The improvement in setting time and workability indicate that AGB can be useful as a retarder and water-reducing admixture, respectively. This suggests that AGB can be integrated into the construction sector, resulting in reducing the chemical admixture demand. Creating new outlets for the AGB material would provide social and economic impacts to construction industry.