Mechanical and Thermal Performance of Cement Bricks with Millet Admixture for Sustainable Building

Wastes recycling offer both ecological and economic potentials on wastes disposal sites and ultimately the sustainability of our natural resources. Experimental evaluation of the mechanical and thermal performance of locally made cement bricks with millet waste as an additive aimed towards improving thermal comfort in buildings is presented. The hot box derived method comprising of a wooden box of dimension 480x350x250mm3 was used. Seven test samples were made with Sample A having zero millet waste content (MWC) and the remaining six having varying MWC. The transient thermal performance of the resulted bio-bricks reveals a uniform behavioural trend for the seven samples, though with different ranges of temperature increase. While the sample with zero MWC appreciably conducts heat faster with its temperature increasing from 28-45.1 degree Celsius within 15 minutes, sample G (with the highest MWC) presents the lowest heat conduction with the temperature range of 28-30.5 degree Celsius over the same period. In addition, the thermal behaviour of the resulted bio-bricks shows that the millet waste inclusion has an inverse effect on its thermal performance as its temperature decreases with increase in MWC, 500grams being the optimum. This is an indicator of the insulating potential of the resulted bio-bricks. The investigation into its mechanical performance shows that its compressive strength decreases with increase in MWC. It is then imperative to mention that MWC should be carefully added both on purpose and to specification so that the mechanical strength of the resulted bio-brick is not compromised unnecessarily.