Abstract:
This study examines the influence of physical properties of fine aggregate, the content in
the concrete, its type, water-to- cement ratio and workability on the compressive strength,
split tensile strength and elastic modulus properties of normal strength concrete. Three
different sources of fine aggregate, Bullen sand, Lalibella sand and crushed stone, were used
to produce concrete with target strengths ranging from 20 MPa to 40 MPa.
For each fine aggregate type, concrete mixes were prepared with two water-to-cement ratios
(0.4 and 0.5) and three fine-to-coarse aggregate ratios (0.5, 1 and 2). Mix design was made
by considering the physical properties of Lalibella fine aggregate whereas the mixes
prepared for Bullen sand and crushed stone fine aggregate have the same amount of water,
cement, and coarse aggregate except for the fine aggregate portion when volume based
replacement is made to see the influence of fine aggregate type. For the study of the effect
of fineness modulus and workability of concrete grade of C20/25, C30/37 and C40/50, with
fineness modulus 2.51 and 2.81 and slump of 25-50 mm and 75-100mm were used. The
specimens used were cylindrical molds with diameter of 10cm and height of 20 cm. The
specimens were kept in a curing chamber until one day before the test.
The concrete made from crushed stone fine aggregate exhibited higher compressive strength
and split tensile strength in all ranges of fine aggregate to coarse aggregate ratio. The
experimental results of splitting tensile strength test were compared with different code of
standards recommendation results and showed that at water-to- cement ratio of 0.5 the codes
gives approximate values while the ratio is about 0.4, and as expected the codes
underestimates the test result. The prediction formula of the modulus of elasticity of
different codes of standards was also compared and it was found that the Chinese’s code
standard GB 50010 code of standards resulted in a higher modulus of elasticity value.