Carbonatable calcium silicate-based cements and concretes having mineral additives, and methods thereof
The invention provides novel methods and novel additive compositions and use thereof in a wide range of concrete production for improving properties of concrete materials, such as durability and aestheticity. The methods and compositions of the invention may be applied in a variety of cement and concrete components in the infrastructure, construction, pavement and landscaping industries.
1. A carbonatable composition, comprising:
calcium silicate, wherein the calcium silicate comprises one or more of CS (wollastonite or pseudowollastonite), C3S2 (rankinite), or C2S (belite, larnite, bredigite) discrete calcium silicate phases, wherein the calcium silicate further comprises an amorphous calcium silicate phase at about 10% or more by mass of the total phases;
one or more melilite type phases having the general formula (Ca,Na,K) 2 [(Mg, Fe 2+ ,Fe 3+ ,Al,Si) 3 O 7 ] or ferrite type phases having the general formula Ca 2 (Al,Fe 3+ ) 2 O 5 ; and
one or more minerals, wherein the one or more minerals are selected from the group consisting of submicron magnesium oxide powder, magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium acetate, and combinations thereof,
elemental Ca and elemental Si are present in the composition at a molar ratio from about 0.5 to about 1.5; and metal oxides of Al, Fe and Mg are present in the composition at about 30% or less by mass, and
the composition is suitable for carbonation with CO 2 at a temperature of about 10° C. to about 90° C. to form CaCO 3 with a mass gain of about 10% or more.
2. The carbonatable composition of claim 1 , wherein the one or more minerals account for about 0.02% to about 20% by weight of the carbonatable composition.
3. The carbonatable composition of claim 1 , comprising one or more residual SiO 2 and CaO phases.
4. The carbonatable composition of claim 1 , comprising about 20% or less of metal oxides of Al, Fe and Mg by total oxide mass.
5. The carbonatable composition of claim 1 , wherein the reactive phases are present at about 50% or more by mass.
6. The carbonatable composition of claim 1 , further comprising a dispersant or superplasticizer.
7. The carbonatable composition of claim 6 , wherein the dispersant or superplasticizer comprises a polycarboxylate-based polymer.
8. The carbonatable composition of claim 1 , further comprising a colorant.
9. The carbonatable composition of claim 8 , wherein the colorant comprises one or more of iron oxide, cobalt oxide and chromium oxide.