Concrete composition
A concrete composition having, in a mixture with water, a hydraulic binder, sand, aggregates, an expanding agent and a shrinkage reducing admixture, wherein the expanding agent is calcium oxide having a low reactivity such that the concrete casted using the composition does not expand by more than 0.05 vol. % during the first 10 days, preferably not expanding more than 0.05 vol. % during the first 7 days, after having been cast.
1. A concrete composition that is
(a) a concrete composition comprising, in a mixture with water, a hydraulic binder, sand, aggregates, an expanding agent, and a shrinkage reducing admixture, wherein the expanding agent is calcium oxide having a low reactivity wherein the concrete does not expand by more than 0.05 vol. %, during the first 10 days, after having been casted; or
(b) a concrete composition comprising, in a mixture with water, a hydraulic binder, sand, aggregates, an expanding agent, and a shrinkage reducing admixture, wherein the expanding agent is calcium oxide having a low reactivity wherein the concrete does not expand by more than 0.05 vol. %, during the first 7 days, after having been casted,
wherein the concrete composition of (a) and the concrete composition of (b) satisfy at least one of the following:
(i) the calcium oxide has a reactivity that is characterized by a conductivity of <11 mS/cm when dissolved in water,
(ii) the calcium oxide has a reactivity that is characterized by an average temperature increase of <0.5° C./min during the first 15 minutes after the addition of the calcium oxide into water, or
(iii) the calcium oxide has a reactivity that is characterized by a temperature increase of <10° C. during the first 5 minutes after the addition of the calcium oxide into water.
2. The concrete composition according to claim 1 , wherein the calcium oxide has a particle size distribution characterized by a residue of at least 6 wt. % on a 45 μm mesh sieve.
3. The concrete composition according to claim 1 , wherein the hydraulic binder comprises ordinary Portland cement and optionally supplementary cementitious material.
4. The concrete composition according to claim 1 , wherein the shrinkage reducing admixture is an organic admixture.
5. The concrete composition according to claim 1 , wherein the mixture further comprises a water reducing agent in an amount of 20-60 ml/100 kg hydraulic binder.
6. The concrete composition according to claim 1 , wherein the volume change of the concrete is between +0.01 and −0.01 vol. % after 365 days after having been casted.
7. The concrete composition according to claim 1 , wherein the concrete composition contains the expanding agent in an amount of 2-6 wt. % of the hydraulic binder.
8. The concrete composition according to claim 1 , wherein the concrete composition contains the shrinkage reducing admixture in an amount of 1-2 wt. % of the hydraulic binder.
9. The concrete composition according to claim 1 , wherein the concrete composition has a water/binder ratio is 0.15-0.50.
10. The concrete composition according to claim 1 , wherein the hydraulic binder is present in an amount of 280-700 kg per cubic meter of concrete.
11. A construction element comprising concrete obtained from a concrete composition according to claim 1 .
12. The concrete composition according to claim 1 , wherein
when the concrete composition is (a), the expanding agent is calcium oxide having a low reactivity, and wherein the concrete does not expand by more than 0.03 vol. % during the first 10 days; or
when the concrete composition is (b), the expanding agent is calcium oxide having a low reactivity, and wherein the concrete does not expand by more than 0.03 vol. % during the first 7 days.
13. The concrete composition according to claim 3 , wherein the optionally supplementary cementitious material comprises granulated blast furnace slag, fly ash, pozzolans or mixtures thereof.
14. The concrete composition according to claim 5 , wherein the water reducing agent comprises a polycarbonate ether based plasticizer admixture or a polynaphthalene sulfonate based plasticizing admixture.
15. The concrete composition according to claim 4 , wherein the shrinkage reducing admixture is an organic admixture based on polypropylene glycol, polyethylene glycol and/or a glycol ether derivative, optionally in a liquid mixture with surfactants.
16. The concrete composition according to claim 1 , wherein the concrete composition of (a) satisfies (i), (ii) and (iii).
17. The concrete composition according to claim 1 , wherein the concrete composition of (b) satisfies (i), (ii) and (iii).