Slags having three different SiO2: Al2O3 ratios (1.2,1.9 and 2.6) and three different CaO contents (44%, 39% and 34%) were prepared. These slags were classified into nine series, in each of which Al2O3 and SiO2 were kept constant and CaO was replaced by MgO in molecular proportion. The hydraulicity of these slags was estimated from the compressive strengths of 1:3 mortars, the cements being prepared from 1.8 parts slag and 1 part hydrated lime by volume. The soundness of the cements produced from some of these slags and portland cement was also measured. Hydraulicity of slag had a tendency to decrease when CaO was molecularly replaced by MgO and it practically did not change when CaO of slag was replaced by MgO on weight basis. Compressive strength increased with the increase of CaO and Al2O3 content of slag and decreased with increase of SiO2 content. The cements produced from high-magnesia slags were perfectly sound and did not show any dimensional instability.

Effect of MgO on Hydraulicity of Slag in the System CaO-Al2O3-SiO2-MgO

Diverses compositions de melange laitier-gypse-chaux ont ete preparees, et conservees sous contrainte; on a pu observer une augmentation de la resistance de ces echantillons par rapport aux echantillons sous expansion libre

Strength increase of expansive slag-sulphate cement under constraint

A few glassy slags in the system, CaO-Al2O3-SiO2 were prepared having a fixed SiO2/Al2O3 ratio of about 1.15 and different proportions of CaO in the range of 35–50 per cent by weight. The hydraulic properties of the slag powders in admixture with different proportions of hydrated lime were studied. The hydraulicity of the slags increased with increase in the proportion of CaO in their chemical compositions and also with the increase of lime in the mixture. The amount of lime necessary for the development of maximum strength was found to decrease with increasing CaO content of the slag.

B. N. Samaddar

Papers

Hydraulicity of Glassy Slags of the System CaO-Al2O3SiO2: I. Influence of the Amount of lime used as Activator and Basicity of Slags on Hydraulicity