ABSTRACT
Concrete was made using a 1/2-in. (12.7 mm) maximum size, crushed-limestone coarse aggregate, river sand, cement type III, and water. Concrete was mixed with the following proportions: 2.0:1.0:0.6:0.3 by weight of coarse aggregate, fine aggregate, cement, and water respectively. The beam specimens were cast in steel molds in three layers and vibrated for 3 minutes on a vibrating table. Six 3 in. (76.2 mm) by 6 in. (152.4 mm) companion specimens were cast simultaneously with the beams to determine the compressive strength of concrete. The notch was formed by placing a 0.5 in. (12.7 mm) by 3 in. (76.2 mm) by 6 in. (152.4 mm) plywood form at the midspan. The plywood was coated with oil before concrete was cast. After casting the concrete, all specimens were cured for 20 days at 100% humidity and 73 °F+/−3 °F (23 °C+/−1.6 °C) and were dried for 1 day at room temperature prior to testing.
