2.1. Materials
Ordinary Portland cement conforms to BS 12 was used (28 day
compressive strength is 54.2 MPa). The specific gravity and specific
surface area of cement were 3.4 g/cm3 and 3950 cm2/g, respectively.
The chemical composition of cement is given in Table 1.
The fine aggregate used was natural river sand having a fineness
modulus of 2.4. The coarse aggregate used was graded gravel with
a maximum size of 30 mm. Three concrete mixes with different