Compressive strength of concrete hollow blocks using crushed glass as substitute aggregates for gravel

Abstract

Waste materials, which are one of the major problems facing the country today, can be minimized if used as aggregates in the construction materials such as concrete hollow blocks. The study aimed to evaluate the compressive strength of concrete hollow blocks (CHB) at different levels of crushed glass as substitute aggregates for pea gravel; to determine if there is a significant difference in the compressive strength of CHB at different mixtures; and to perform the economic analysis in the fabrication of CHB at different mixtures. The study was conducted at the laboratory building of the Agricultural Engineering Department of Capiz State University, Burias Campus, Mambusao, Capiz from January 23 to February 20, 2012. Compressive strength test was conducted after 28 days of curing at the Provincial Material Testing Laboratory of the Department of Public Works and Highways (DPWH) in Roxas City, Capiz on February 21, 2012. CHB was evaluated using four different levels of crushed glass substituted to pea gravel corresponding to four different mixtures, namely: Treatment A- 0% Crushed Glass (CG), 100% Pea Gravel (PG); Treatment B- 25% CG, 75% PG; Treatment C- 35% CG, 65% PG; and Treatment D- 45% CG, 55% PG. Each treatment was replicated three times. The treatments were arranged in a Completely Randomized Design. Data were analyzed using ANOVA and LSD and were interpreted at 5% level of significance. Results showed that the compressive strength of all CHB at different levels of crushed glass were within the required compressive strength range of 197 psi to 386 psi for non-load bearing CHB set by Forest Product Research and Industries Development Commission. Concrete hollow blocks mixed with 25% crushed glass obtained significantly the highest compressive strength of 298.01 psi, while CHB mixed with 35% CG, 45% CG, and 0% CG had comparable compressive strengths. The highest annual income generated was ₱ 68,488.98 from CHB mixed with 45% CG, while the lowest was ₱ 67,037.46 obtained from CHB without crushed glass. The return on investment, payback period and break-even point for the production of CHB with 45% CG were 139.28%, 262.07 days, and 19,671 CHB/yr, respectively.