Comparative Evaluation of Musa Paradisiaca Pseudo-stem Pith Fluid and Sodium Phosphate as Retarders in Cement Mortar

Abstract

The study compares the retarding effect of plantain pseudo-stem pith fluid with that of sodium phosphate in mortar with a view to ascertaining the efficacy of the former as eco-friendly retarder for sustainable construction in developing countries. A cement paste of cement and water, and mortar mix of 1: 3: 0.45 (cement: Fine aggregate: water/cement ratio) by weight, respectively were prepared as reference; and subsequently, each of the retarders in the range of 0 to 1% by weight of water were added as replacement to the mixing water. Consistency and setting times of the paste were tested; and 50mm cube mortar and 160 mm × 40 mm × 40 mm prism were cast and tested for compressive and flexural strength up to 28 days. The results revealed that the consistency range from 26.7% to 30.4% for both retarders, and the setting times delayed more for blended pastes than the reference. The highest compressive strength of 26.93 N/mm² and 27.33 N/mm² were attained with sodium phosphate dosage of 0.625% and plantain pseudo-stem pith fluid of 0.865% dosage, respectively at 28 days hydration. The flexural strength of sodium phosphate mortar specimens at 28 days attained higher values than that of plantain pseudo-stem pith fluid and the reference. Statistical test (t-test) on consistency, setting times and compressive strength values of the two retarders indicates no significant difference. Therefore, the study concluded that plantain pseudo-stem pith fluid of 0.825% as water replacement in mortar mix is a good bio admixture to commercial retarders.