Dolomite and limestone micro filler: early-age properties and soundness on blended cement

EDGARDO FABIAN IRASSAR; ANTONELA DI SALVO; , GUILLERMINA MARCHETTI; VIVIANA RAHHAL; MÓNICA TREZZA

Praga

Congreso; 15TH International Congress on the Chemistry of Cement. Praga, República Checa; 2019

This study investigates the physical and chemical effects of dolomite microfiller in Portland blendedcements comparing to limestone filler. Dolomite (CaMg(CO3)2) is limited as filler due to the potentialdedolomitization in high alkaline environment of the paste. Natural Dolomite (D) and limestone (L)were ground fine particles with median size of 10 m and included as partial replacement to ordinaryPortland cement (OPC) up to 30% by weight. The packing density and the water film thickness wereevaluated for both fillers with similar particle size distribution. For 10, 20 and 30% of replacements, theeffect of dolomite on water demand, the isothermal calorimetric, the setting time and the compressivestrength at 1, 2, 7, 28 and 90 days was determined. For C0, C20D and C20L, the hydrationcompounds were determined by XRD at 2, 28 and 90 days and the CH content was determined TGanalysis at 28 days. Dolomite filler increases the packing density and the specific surface area,reduced the initial mini-slump test and improve the mortar flow due to the complementary effect on theWTF. Dolomite particles act as sites for nucleation and growth of cement hydration productsstimulating the early hydration of PC as shown the calorimetric curve and reducing the setting time.Early compressive strength depends on stimulation and dilution effects of D. At later ages, theformation of AFm phases (Hc and Mc) occurs without the formation of brucite indicating that dolomiteremains stable. D-PC performs comparably to L-PC without noticeable deleterious reactions