SYMPOSIA PAPER Published: 01 January 1990

The Influence of Limestone Additions on Optimum Sulfur Trioxide Content in Portland Cements


This paper shows an experiment carried out with Brazilian materials (clinker, limestone, and natural gypsum) to determine the optimum sulfur trioxide (SO3) content, varying the degree of fineness and the limestone content in the cements which were obtained by grinding them together, in the laboratory.

The laboratory tests were based on the ASTM Test for Optimum SO3 in Portland Cement (C 563-84) Method, adapted to Brazilian conditions. The compressive strength was determined by the cylindrical test specimens of the Brazilian Standard Method using Brazilian Standard sand.

An effective influence of the addition rate of limestone and its degree of fineness on the optimum SO3 content on the compressive strength value at 24 h after mixing of test mortar was determined.

Limestone additions to Portland cement influence the optimum SO3 content due mainly to its effect on the particle size distribution of cement and perhaps to the reaction of calcium carbonate with the clinker tricalcium aluminate.

Author Information

Campiteli, VC
Escola Politécnica of University of São Paulo, Sao Paulo, Brazil
Florindo, MC
Concrete Technology Group, Instituto de Pesquisas Tecnologicas, IPT, São Paulo, Brazil
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Developed by Committee: C01
Pages: 30–40
DOI: 10.1520/STP23469S
ISBN-EB: 978-0-8031-5125-3
ISBN-13: 978-0-8031-1454-8