Abstract:
To investigate the fresh and hardened properties of concrete, four different maximum aggregate sizes (12.5 mm, 19.0 mm, 25.0 mm and 37.5 mm) have been used. Bricks were collected and broken into pieces according to the grading requirements of ASTM C 33–03. Several tests as specific gravity, absorption capacity, unit weight, and abrasion resistance were performed for coarse aggregate. Cylindrical concrete specimens of diameter 100 mm and length 200 mm were made with different sand to total aggregate volume ratio (s/a) (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375 kg/m3 and 400 kg/m3). A total of 48 different cases were considered and a total of 384 concrete specimens were made for testing. The specimens were tested for compressive strength, stress-strain curve, and Young's modulus at the age of 7 days, and 28 days. Non-destructive tests as Schmidt hammer test, Ultrasonic Pulse Velocity (UPV) were also performed. To conduct UPV test Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT) were used.
Results have revealed that for a higher cement content, smaller sized brick coarse aggregate (12.5 mm) gives higher compressive strength, splitting tensile strength, and Young’s modulus of concrete. But for a lower cement content, and lower W/C ratio, these properties tend to increase with an increase in maximum size of aggregate. The compressive strength of concrete increases with an increase in s/a ratio from 0.40 to 0.45. Based on the experimental results, relationships between compressive strength and Young's modulus, compressive strength and tensile strength, and stress-strain relationships are proposed for different maximum sizes of brick aggregate.
