Title : DURABILITY AND MICROSTRUCTURE OF MORTAR WHERE CEMENT IS REPLACED BY CALCINED MAR
Authors : Tone A.Østnor and Harald Justne
Publication :
Volume :
Pages :
Price : 250
Abstract : Mortars (sand:cement = 3:1 and w/c = 0.50) were made where Portland cement was replaced with 0, 20, 35, 50 and 65 vol% calcined marl. The compressive and flexural strengths were determined after 1, 3, 7, 28, 90, 365 and 730 days curing at 90% RH and 23°C. The strength up to 28 days age was higher or equal to the reference for up to 50 vol% marl replacement of cement, while only 20 and 35 vol% replacements gave higher strength than reference at 90 days. The strength of mortar with 65 vol% calcined marl continued to increase until 2 years and approached the strength of mortars with 35 and 50 vol% cement replacements. The microstructure of the mortars was characterized by SEM after 90 days and 2 years curing, as well as capillary suction and saturation giving total volume of capillary pores and amount of macro pores. Electrical resistivity was also measured. Mortars of all compositions were tested for durability starting after 90 days curing with respect to chloride diffusion, expansion caused by sulphate attack (5% Na2SO4) at both +5°C and +20°C, as well as carbonation (accelerated by 1% CO2 and 60% RH).