Author
Abstract
The objective of this investigation is to find the effectiveness of the citric acid as
retarding admixture. The experimental results indicate that the optimum dosage of citric
acid is 0.02% by weight of cement. This dosage causes a delay in initial and final setting
time of 1:42 and 3:18 hour: minute, respectively; and a reduction in water-cement ratio
of 13% relative to reference concrete mix. So, citric acid can be classified according to
ASTM-C494 as water-reducing and retarding chemical admixture type D.
The investigation also extends to evaluate the effect of using citric acid on
properties of concrete such as, compressive strength, splitting tensile strength, modulus
of rupture and dynamic modulus of elasticity at normal conditions and after exposure to
salt solutions. Generally the results indicate that using citric acid in concrete enhance it's
properties at normal conditions, the percentage increase in compressive strength,
splitting tensile strength, modulus of rupture and dynamic modulus of elasticity at age
180 days was about 56%, 13%, 24% and 8% respectively relative to reference concrete.
Also it was observed that concrete containing citric acid has good performance after 180
days exposure to salt solution in comparison with reference concrete.
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