The chemical composition and specific surface of the mine
waste mud are shown in Table 2. Table 3 shows gradation and
physical characteristics of aggregates. Limestone and granitic
coarse aggregates have the same Faury maximum dimension
(9.52) and similar fineness modulus respectively 5.5 and 5.2.
Schist sand has a lower maximum dimension (2.78) and a
fineness modulus of 2.38.
2.2. Mix proportion, strength testing and microanalysis of the
binders
The samples composition is shown in Table 4. In this
investigation the mortar was a mixture of aggregates, waste
mud, calcium hydroxide, alkaline silicate solution and water.
The mass ratio of mine waste mud: activator was 1:1. Calcium
hydroxide was used with a percentage substitution of 10%,
because it was found that percentage leads to the highest
compressive strengths. An activator with sodium hydroxide
(24 M) and sodium silicate solution (Na2O=8.6%, SiO2=
27.8%, Al2O3=0.4% and water=63.2%) was used with a mass
ratio of 1:2.5. Previous investigations showed that this ratio
leads to the highest compressive strength results in alkaliactivated
mine waste mud mortars [29]. Distilled water was
used to dissolve the sodium hydroxide flakes to avoid the effect