METHOD FOR THE PRODUCTION OF A CEMENTITIOUS MATERIAL

Abstract

A method for producing cementitious material involves mixing 100 parts by weight of a first mixture with 8 to 12 parts by weight of water to obtain a first slurry. The first mixture has, in a percentage by weight, 20 to 25% of a cement selected from Portland cement, limestone cement, slag cement, pozzolanic cement, composite cement and mixtures thereof, 0 to 6% of calcium sulfate, 65 to 80% of inert material, and 1 to 4% of SO.sub.3. A second slurry is obtained by mixing 100 parts by weight of a second mixture with 30 to 45 parts of water. The second mixture has, in a percentage by weight, 85 to 100% of a cement selected from calcium sulfoaluminate (CSA) cement, aluminous cement and mixtures thereof, 0 to 15% of inert material, and 5 to 13% of SO.sub.3. The second mixture is added to the first mixture with a weight ratio between 0.10 and 0.20.

Claims

1. A method for producing a cementitious material, the method comprising: mixing 100 parts by weight of a first mixture with 8 to 12 parts by weight of water to obtain a first slurry, said first mixture comprising from 20 to 25% by weight of a cement selected from the group consisting of Portland cement, limestone cement, slag cement, pozzolanic cement, composite cement and mixtures thereof, from 0 to 6% by weight of calcium sulfate, and from 65 to 80% by weight of inert material, and having a SO.sub.3 content by weight from 1 to 4%, after obtaining the first slurry, mixing 100 parts by weight of a second mixture with 30 to 45 parts of water to obtain a second slurry, said second mixture comprising from 85 to 100% by weight of a cement selected from the group consisting of calcium sulfoaluminate (CSA) cement, aluminous cement and mixtures thereof, and from 0 to 15% by weight of inert material, and having a SO.sub.3 content from 5 to 13% by weight, and adding said second slurry to the first slurry with a ratio of 0.10 to 0.20 by weight between the second slurry and the first slurry, and mixing to obtain said cementitious material.

2. The method of claim 1, wherein said second mixture further comprises up to 2% by weight of a retarder, up to 0.5% by weight of a lithium salt, and/or up to 2% by weight of CaO.

3. The method of claim 1, wherein at least one of said first and second mixtures further comprises up to 3% by weight of a fluidizer.

4. The method of claim 1, wherein said CSA cement has a C.sub.4A.sub.3$ content of more than 30% by weight.

5. The method of claim 1, wherein said first mixture comprises from 2 to 6% by weight of calcium sulfate.

6. The method of claim 1, wherein said second mixture comprises from 1 to 5% by weight of inert material.

7. A mortar obtainable by the method of claim 1.

8. A concrete obtainable by the method of claim 1.

9. The concrete of claim 8, wherein the concrete is used by casting into a formwork or by extrusion.

Description

EXAMPLE

[0019] A first mixture consisting of the components listed in Table I and having a SO.sub.3 content by weight equal to 2.7% is mixed with 175 g of water for 45 minutes, so as to obtain a first slurry.

TABLE-US-00001 TABLE I Quantity % on % on % on total Component (g) dry basis total dry binder CEM I 52.5 R 420 22.63 20.46 59.8 Anhydrite 70 3.77 3.41 10.0 CaO 7 0.38 0.34 1.0 Normal sand 1350 72.74 65.77 Sika P22 liquid fluidizer 9 0.48 0.44 1.3

[0020] A second mixture consisting of the components listed in Table II is mixed with 75 g of water for 5 minutes, so as to obtain a second slurry. The CSA cement or binder of the second mixture contains 60% by weight of C.sub.4A.sub.3$. The SO.sub.3 content of the second mixture is equal to 8.3% by weight.

TABLE-US-00002 TABLE II Quantity % on dry % on % on total Component (g) slurry total dry binder Sulfoaluminate binder 190 96.64 9.26 27.0 Lithium carbonate 0.7 0.36 0.03 0.1 Citric acid 1.4 0.71 0.07 0.2 Sika P22 liquid fluidizer 4.5 2.29 0.22 0.6

[0021] The second mixture is added to the first mixture and mixed for a period of time equal to 5 minutes until a homogeneous cementitious material is obtained, which is suitably fluid so that it may be easily poured into a formwork. The evolution of the compressive strength of the poured cementitious material over time is described in Table III.

TABLE-US-00003 TABLE III Compressive strength 2 h (MPa) 18.5 Compressive strength 3 h (MPa) 25.3 Compressive strength 24 h (MPa) 37.5 Compressive strength 7 days (MPa) 61.7 Compressive strength 28 days (MPa) 74.8

[0022] Without prejudice to the principle underlying the invention, details of implementation and embodiments may vary widely with respect to that which has been disclosed purely by way of example, without thereby departing from the scope of the invention as defined in the appended claims. In particular, the above mixtures may also contain any conventionally used additive, such as fluidizers, retarders, expanders and the like, alone or in combination.