Performance of Concrete Incorporating Limestone Dust as Partial Replacement for Sand
V. M. Malhotra and G. G. Carette
Appears on pages(s):
compressive strength; concretes; creep properties; dust; fine aggregate;freeze-thaw durability; limestone: shrinkage.
Accumulation of vast amounts of limestone dust at stone quarries around the country is a cause for serious concern because of the disposal problem and environmental hazards. This investigation was thus undertaken to obtain data on the mechanical properties and durability of concrete incorporating various percentages of limestone dust as a partial replacement for fine aggregate. Three series of concrete mixtures were made. Series I and II with water-cement ratios of 0.70 and 0.53, respectively, consisted of mixtures incorporating 5, IO, 15, and 20 percent limestone dust, whereas Series III with a water-cement ratio of 0.40 covered mixtures containing 10 and 20 percent dust. A control mix was also included in each series. Both control and limestone dust mixtures were proportioned to have a slump of 80 f 15 mm (3.0 + 0.5 in.) and an air content of 6 + 0.5percent. The incorporation of up to IO percent limestone dust as a partial replacement for fine aggregate in concrete with a 0.70 water-cement ratio and 5 percent limestone dust in concrete with a 0.53 water-cement ratio does not significantly affect the properties of fresh and hardened concrete. The loss in entrained-air content can be easily overcome by using an increased dosage of an air-entraining admixture . The increase in shrinkage of concrete appears to be of little practical consequence. The use of limestone dust imparts more cohesiveness to fresh concrete and gives it a fatty appearance. This can be a decided advantage in superplasticized concrete.