Enhancing the Structural Properties of Mortar with Treated Rubber Crumb

Abstract: The applications of mortar in infrastructural developments cannot be overemphasized owing to its significances which are evident in the formation of composite structures. More importantly, mortar is one of the best construction materials required for the construction of building blocks, filling the gaps between blocks. It is a universally acceptable construction material because of its good structural and compatibility properties such as good flexibility and transformative capacity, and good binding property. As a flexible construction material, mortar is used as binder in masonry and walling units. The applications of mortar for construction purposes have highly contributed to the development of the built environment. However, ,mortar may deteriorate by deforming into powdery after used for construction, and turning into crumbling material. Thus, this research investigates on enhancing the fresh and hardened properties of mortar using rubber crumb treated with sodium hydroxide (NaOH). The strength properties of the rubber – mortar produced were evaluated through the physical and chemical properties of rubber; the consistency, workability, setting times of rubber - cement paste; compressive and flexural strengths of rubber – cement - mortar. The chemical composition and physical characterization of rubber crumb were evaluated by determining its fineness modulus, water absorption, bulk density, ash content, metal content and fibre content according to SANS 3001-AG1 and SANS 3001-AG20. Also, the workability, consistency and setting times, compressive and flexural strengths of mortar were determined according to ASTM C 1437, SANS 50196-3 and SANS 50196-1. The results of the experiment show that, the rubber treated with NaOH has good physical and chemical properties for enhancement of mortar’s fresh and hardened properties. The rubber – cement paste’s workability increases with increase in the percentage of rubber included. Also, the consistency of the mortar paste increased by 0.5 – 2.0% with increase in the value of rubber included. In addition, the application of rubber in mortar reduced its initial setting time while its final setting increases with increase in rubber content. The addition of 1.5% of rubber crumb increased the compressive strength of mortar by 3.32%, 9.13%, and 0.21% at 7, 14 and 28 days of curing respectively. Also, 1.5% rubber crumb increased the flexural strength of mortar by 5.94% at 28 days. In conclusion, the incorporation of 1.5% rubber crumb in mortar enhanced its mechanical properties.

Keywords: Mortar, Rubber crumb, Setting Times, Consistency, Compressive and Flexural Strengths

DOI: 10.54941/ahfe1005740

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