Showing papers on "Portlandite published in 1986"
TL;DR: In this paper, the factors which control carbonate cementation have been examined and several hypothesis developed to explain their interaction, such as the pressure, concentration, temperature and velocity of the carbonating gas as well as the thickness, temperature, gas permeability, moisture and Ca(OH)2 contents of the compact.
170 citations
01 Jan 1986
TL;DR: In this article, the effects produced by the presence of pfa upon the hydration characteristics of an ordinary portland cement, compared with two equivalent pastes were obtained using two equivalent pretrained pastes.
Abstract: In order to examine the effects produced by the presence of pfa upon the hydration characteristics of an ordinary portland cement, comparisons were obtained using two equivalent pastes. One of these pastes was prepared with an ordinary portland cement and the other with a blend containing 30 parts by weight of pfa and 70 parts by weight of the opc. Both pastes were made so as to have a water to solids ratio of 0.47 by weight. The chemical composition and the physical characteristics of the starting materials are shown. The following quantitative measurements were made after 0.25, 0.5, 1, 1.5, 2, 7, 14, 28, 65, 100, 275 and 365 days hydration at room temperature: 1) compressive strength (at ages greater than 1.5 days); 2) total porosity (at ages greater than 1.5 days); 3) chemically bound water; 4) calcium hydroxide (portlandite) content; 5) hydration of the individual cement phases; 6) reaction of the "glassy" phase in the pfa. Two distinct mechanisms are shown to occur. At early ages the pfa does not make a strong contribution to strength but, as a fine powder, it accelerates the hydration of the cement. The pozzolanic reaction becomes apparent at normal temperature if curing has continued beyond fourteen days. (TRRL)
21 citations