Developments in the Manufacture and Use of Portland Limestone Cement
Graeme K. Moir and Steven Kelham
Appears on pages(s):
Clinker; durability; environments; mineralizers
The short term performance aspects of portland limestone cements (setting, concrete slump, strength development and heat of hydration) are compared with those of portland slag, fly ash and pozzolanic cements. The early activity of the portland limestone cements, as indicated by initial setting time, early strength and early heat release, is generally higher than that of the other cement types. Ultimate strengths are, however, lower provided moist curing conditions are maintained. The longer term performance characteristics of, concrete carbonation rate, freeze-thaw resistance, sulfate resistance and chloride penetration are also compared. Generally the performance of cements containing up to 25% limestone was satisfactory and within the range of performance of the portland cements from 4 different sources. Portland limestone cements with similar late strengths and superior early strengths to normal portland cements can be produced if active mineralised clinker is used as the basis of the cement. The environmental impact of cement manufacture is reduced with this type of cement. The effective utilisation of portland limestone cements is dependent upon having appropriate cement and concrete standards in place. The European countries have largely achieved this and are in a good position to gain the economic and environmental advantages of portland limestone cement manufacture and use.