The use of limestone powder as an alternative cement replacement material: An experimental study

Abstract

This research paper examines the effects of partial substitution of Portland cement clinker with limestone addition on the physical and chemical properties of cement paste and hardened mortar in two ranges of blain fineness values. Laboratory tests were conducted on limestone and clinker samples before used for the intended purpose and then checked for conformity with the Ethiopian and European standards.

The laboratory test results revealed that up to 15% replacement of clinker by fine limestone powder having blain fineness values in the range of 4000 to 4500 cm²/gm result in comparable compressive strength to similar mixes produced using 100% ordinary Portland cement. It also satisfied the standard compressive strength of high early strength of cement (42.5 MPa) as per EN 197-1 standard requirements. Furthermore, it was found that 25-35% limestone addition by weight results in slightly lesser compressive strength values than the 28^th day’s standard compressive strength requirement.

Observations on the test results further indicated that increasing in fineness of the limestone filler addition in Portland cement clinker results in relative increase of rate of hydration and faster development of the early age strength while decreasing slightly the consistency and the setting times (initial and final). The loss on ignition is also observed to increase with the increase in percentage proportion of limestone filler addition where as the percentage by mass of sulphate trioxide and insoluble residue as well as soundness effect of the Portland limestone cement remain within the acceptable range.

Keywords: Calcium carbonate, Compressive strength, Early strength, Limestone filler, Loss on ignition, Portland limestone cement