DETERMINATION OF MIX DESIGN OF CONRETE GRADE 30N/MM2 FOR BORED PILE
Salihu Andaa Yunusa1, Abubakar Sani Kazaure2 and Abubakar Ahmadu3
Department of Civil Engineering
Kaduna Polytechnic, Kaduna
Email: andaayunusa@yahoo.com
ABSTRACT
The increasing failure of bridges piles and other structures faced by the construction industry in Nigeria due to weak concrete strength has made it necessary to understand the causes of failure of these structures. Research was carried out to study the mix design for concrete grade 30N/mm2 for bored piles. Tests on aggregates from Kaduna and cement from Dangote were carried out and concrete cubes were cast in order to determine the compressive strength and densities. Three tests were carried out before we could arrive at satisfactory results as specified by the B.S 4450. The compressive strength of the concrete cubes at seven days and twenty eight days were determined. The strengths of the first tests were 18.7 N/mm2, 20.0 N/mm2, 19.4 N/mm2 and 28.9 N/mm2, 27.6N/mm2, 26.7N/mm2 respectively. The second tests were 19.6N/mm2, 19.1N/mm2 and 30.2N/mm2, 29.9N/mm2, 29.3N/mm2 respectively. The third test which gave us the desired results were 24.4N/mm2, 23.9N/mm2, 24.3N/mm2 and 32.2N/mm2, 32.4 N/mm2, 31.9N/mm2 respectively. The standard consistency of the cement tested was 28% with initial and final setting time of 2hr. 44 minutes and 5hr. 54minutes respectively. The densities of the cubes at seven days and 28dyas were also determined. The first set were 2.36 g/cm3, 2.34 g/cm3 2.32 g/cm3 and 2.41 g/cm3, 2.39 g/cm3, 2.43g/cm3 respectively. The second set were 2.41 g/cm3, 2.39g/cm3, 2.43g/cm3. And 2.44g/cm3, 2.46g/cm3, 2.42g/cm3 respectively. The third set were 2.39g/cm3, 2.40 g/cm3, 2.36 g/cm3 and 2.41g/cm3, 2.39g/cm3, 2.40g/cm3 respectively.