4. Results and discussion
4.1. Workability
The result for the workability of tire-crumb-incorporated mortars is shown in Fig. 2. This revealed a decrease in the workability with an increase in tire crumb content. The flow increased by approximately 7% at 10% tire crumb content as compare to the control sample before it gradually decreased as the tire crumb content increased. The increase in workability at 10% tire crumb content is due to the volume of the mineral aggregate which dominates the sample and permits water to flow between it grains leading to the increments. The reduction in workability with increase tire crumb content is due to the nature of tire crumb particles which repels water. This is in agreement and consistent with the finding by researchers such as Khatib and Bayomy [5], Cairns and Kenny [11], Guneyisi et al. [29] and Khaloo et al. [13].
The addition of oil palm fruit fibre oil palm fruit fibre (OPFF) in the matrix further reduces the workability for all of the tire-crumb-incorporated mixes. The decrease in workability due to addition of OPFF is as a result of the high water absorption nature of OPFF, which tends to absorb the available water during mixing. The decrease in work- ability becomes more pronounced at higher tire crumb content. The behaviour exhibited by the samples containing tire crumb moves towards zero slump at a 50% tire crumb content and this is similar to results by Khatib and Bayomy [5], Cairns and Kenny [11], and Guneyisi et al. [29].