Abstract:
The quality of building materials has been documented to be one of the causes of
building collapse all over the world. An experimental study was conducted to determine the
effect of fines (clay/silt) content in sand and water-to-cement ratio on the workability,
compressive strength, tensile strength and flexural strength of concrete. A total of 270
specimens were cast and tested with varying fines content in sand of 2%, 4%, 6%, 8%,
10% and 12%; and variable water-to-cement ratio of 0.55, 0.60 and 0.70. A basic 1:2:4
concrete mix ratio was adopted for the study through trial mix. Mixing, compaction, curing
and testing were performed in accordance with BS and ASTM standards. The results show
that, workability of concrete decreased and increased as the percentage of fines in sand and
water-to-cement ratio respectively increased. The study again revealed that compressive,
tensile and flexural strength of concrete increased to 4% fines content in sand beyond
which they decreased at constant water-to-cement ratio. Equations for predicting the
workability (Wc = -141.905 – 235.714CS + 310.476w/c; R2=0.899), and compressive
strength (fcu,28 = 45.357 – 37.143CS – 41.136w/c; R2=0.848), tensile splitting strength (fct,28
= 3.532 – 3.195CS – 2.798w/c; R2=0.836) and flexural strength of reinforced concrete
(fcf,28 = 30.485 – 23.076CS – 24.507w/c; R2=0.905 ) were proposed valid for 4% fines in
sand and beyond. It was concluded from the study that, fines percentage in sand and water to-cement ratio beyond 4% and 0.57 respectively affect concrete properties negatively.
Concrete designers and producers are therefore advised to pay attention to the percentage
of fines in sand and water-to-cement ratio on site.
Description:
A Dissertation in the Department of Construction and Wood Technology Education,
Faculty of Technical Education, submitted to the School of Graduate Studies,
University of Education, Winneba in partial fulfilment of the requirements for award
of the Master of Philosophy (Construction Technology) degree.
JULY, 2016