SEDL / STP / STP1064-EB / STP23469S

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

Campiteli, VC
Associate professortraineepostgraduate student, State University of Ponta GrossaInstituto de Pesquisas TecnológicasEscola Politécnica of University of São Paulo, ParanaSao Paulo,

Florindo, MC
Researcher, Concrete Technology Group, Instituto de Pesquisas Tecnologicas, IPT, São Paulo,

Pages: 11    Published: Jan 1990

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Abstract

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.