Preparation and Assessment of Arabic Gum-Polycarboxylate Blends as An Effective Superplasticizer for Cement Mortars.

The enhancement action of superplasticizers with biodegradable and eco-friendly materials such as Arabic gum is the main goal of this work. Polycarboxylate superplasticizers (PCs) based on the macromonomer from isopentenyl polyethylene glycol (TPEG, with Mw 2400) and the carboxylic monomer of acrylic acid (AA) and the natural polymer (Arabic gum, AG) were prepared at different polymerization conditions. The synthesized polymers were characterized by FTIR and 1H-NMR. In addition, evaluation of their rheological properties such as setting times, and soundness to select the best polymer composition to blend it with the different ratios of Arabic gum. The characterization tests evidenced the complete polymerization between TPEG and AA for all prepared polymers but the best composition according to the rheology test was PC-4 which consisted of 80 % AA and 20% TPEG. Blend PC-4 with 0.5 % Arabic gum giving higher compressive strength values of about 150.37 % and 131.15% compared with the blank sample (OPC) at 2 and 28 days of hydration, respectively. Moreover, the incorporation of Arabic gum in the PC-8 sample increased the hydration products and enhanced the microstructure of the hydrated pastes compared with PC-4 (without Arabic gum) and Blank sample. The above results were evidenced by measuring the compressive strength, XRD, and SEM for the hydrated cement mixes at early and late hydration times.