Sanni Mukaila Yinka (1), Leonard Ngutor Dugguh (1) and  Laraiyetan Ebenezer Taiye (2)

(1) Department of Civil Engineering, Ahmadu Bello University, Zaria, Kaduna State, Nigeria
(2) Department of Civil Engineering, Kogi State Polytechnic, Lokoja, Kogi State, Nigeria

This paper experimentally investigates the capillary pressure and porosity of masonry concrete block containing waste tyre (crumb-rubber) with varying ratios ranging from 0 – 25 %, which was used to partially replace coarse aggregate (granite) by volume. The bulk density of masonry concrete decreased by 5.4 % with crumb-rubber content up to 25 %. Porosity (f) of masonry concrete (24 hours water absorption, vacuum saturation, satiation, and vacuum satiation porosity) increased with an increase in crumb-rubber content. The capillary pressure test result for both the initial and refined (modified) method shows a rapid increase from 0 % to 5 % before gradually increasing with a further increase in crumb-rubber content up to 25 %.
The average capillary pressure value for the reference masonry concrete using the initial and refined method is 0.166 MPa and 0.128 MPa while the modified concrete with 25 % crumb-rubber particles recorded 0.289 MPa and 0.233 MPa respectively indicating 74 % and 82 % increase respectively. Generally, the increase in capillary pressure can be directly linked to the increase in voids in the composite matrix which also increased the porosity. These results signify an increase in the capacity of modified masonry concrete to absorb water through the capillary rise.

Keywords: Crumb-Rubber; Masonry Concrete; Capillary Pressure and Porosity