| Summary, etc |
The increasing cost and scarcity of portland cement has impacted negatively on the delivery of the affordable housing and infrastructure develpment in third world countries like the Philippines. This study investigated the use of waste wood as a partial substitute for portland cement inthe production of concrete . Six concrete cylinders with a diameter of 6 inches and a height of 12 inches, and 3 concrete cylinders with the diameter of 6.3 inches and a height of 12 inches were made for six different concrete mixes prepared by using waste wood ash (WWA) to substitute 0%,10%,15%,20%,25%, and 30% of portland cement by mass. The workability of fresh concrete mixes was evaluated using the slump test while compressive strengths of concrete cylinders were evaluated at a 21-day curing period. From the test results, the slump decreased as the WWA content increased indicating that concrete becomes less workable and requires greater water demand . On the other hand, the maximum compressive strength among the 6 mixes was obtained at 20% WWA substitution. It was then concluded that the optimum level of substitution exists at which the compressive strength is the highest, even higher than the control. Hence, the maximum allowable replacement of waste ash is at 20% replacement of the mass of the cement.<br/><br/>Thus, based on the result,WWA substitution can only be used in residential structures which only require low to medium concrete strength of 2500 psi (17 MPa) |