METHOD FOR THE REFURBISHMENT OF POROUS CONSTRUCTION MATERIALS

Abstract

A method for the refurbishment of porous construction materials and a composition including Portland cement, calcined clay, and optionally aggregate to be used in the method for the refurbishment of porous construction materials. The method includes the steps of mixing water and a composition C, the composition C including, a) 100 mass parts of Portland Cement, b) 1-18 mass parts, preferably 1-10 mass parts, more preferably 1-7.5 mass parts, still more preferably 1-6 mass parts, especially 1-5 mass parts of calcined clay, c) optionally 10-250 mass parts of aggregates, applying the mixture thus obtained to a porous construction material, and optionally hardening the applied mixture.

Claims

1. A method for the refurbishment of porous construction materials, the method comprising the steps of mixing water and a composition C, the composition C comprising, a) 100 mass parts of Portland Cement, b) 1-18 mass parts of calcined clay, c) optionally 10-250 mass parts of aggregates, applying the mixture thus obtained to a porous construction material, and optionally hardening the applied mixture.

2. The method according to claim 1, wherein the calcined clay is metakaolin.

3. The method according to claim 1, wherein the Portland cement is Portland Cement with a Blaine surface as measured according to EN 196-6:2010 of 1′500-10′000 cm2/g.

4. The method according to claim 1, wherein the method is selected from the group consisting of a method for the protection against ingress according to method 1.3 of standard EN 1504-9, a method for the moisture control according to method 2.3 of standard EN 1504-9, a method for concrete restoration according to method 3.1 or 3.3 of standard EN 1504-9, a method for structural strengthening according to method 4.4 of standard EN 1504-9, a method for increasing the physical resistance according to methods 5.1 or 5.3 of standard EN 1504-9, a method of increasing the resistance to chemicals according to method 6.3 of standard EN 1504-9, a method of preserving or restoring passivity according to methods 7.1 or 7.2 of standard EN 1504-9, a method of increasing the resistivity according to method 8.3 of standard EN 1504-9.

5. The method according to claim 1, wherein the method additionally comprises one or more further steps selected from removing part of the porous construction material, cleaning the surface of the porous construction material, and/or priming the surface.

6. The method according to claim 1, wherein the method additionally comprises one or more further steps selected from the application of further layers on top of the mixture of water and a composition C.

7. The method according to claim 1, wherein the mixture of water and composition C is applied in a one-step procedure as one layer or in a multiple-step procedure as two or three layers to yield a total layer thickness of 0.5-50 mm.

8. The method according to claim 1, wherein the mixture of water and a composition C is applied by trowel, brush or roller.

9. The method according to claim 1, wherein the mixture of water and a composition C is applied in a spray application.

10. A dry composition C for use in a method according to claim 1, the dry composition C comprising a) 100 mass parts of at least one binder selected from Portland cement, b) 1-18 mass parts of calcined clay, c) optionally 10-250 mass parts of aggregates.

11. A wet composition obtained by mixing a dry composition C according to claim 1 with water in a water to powder ratio of 1:1 to 1:11.

12. A porous construction material obtained by a method according to claim 1.

13. A porous construction material according to claim 12, wherein it is part of basement walls, floor structures, drainages, pipes, silos, stairs, bathrooms, kitchens, swimming pools, balconies, terraces, ponds or basins, harbor structures or works of civil engineering.

Description

EXAMPLES

[0090] The following table 1 gives an overview of the raw materials used

TABLE-US-00001 TABLE 1 Raw materials used OPC 1 CEM I 52.5 R (grey) OPC 2 CEM I 52.5 R (white) Sand Quartz sand (0.1-2 mm) MK 1 Metakaolin from high purity kaolin clay (0.1% of particles >44 μm) MK 2 Metakaolin from high purity kaolin clay (D90: 15 μm, D50: 3.2 μm) MK 3 Metakaolin from kaolinitic clay (D50 = 2 μm; BET surface 19 m.sup.2/g) Plasticizer Sodium salt of a sulfamic acid modified melamine-formaldehyde polymer Defoamer Axilat DF770DD

[0091] Test Methods

[0092] Compressive strength was measured according to standard EN 12190 on 4×4×16 cm prisms. The compressive strength was tested after curing of the test specimen for the time indicated in the below table at 23° C. and 50% r.h.

[0093] Flexural strength was measured according to standard EN 196-1 on prisms 40×40×160 mm after curing of the test specimen for the time indicated in the below table at 23° C. and 50% r.h.

[0094] Capillary absorption was tested according to standard EN 13057.

[0095] Carbonation depth was measured according to standard UNE EN 14630.

Examples 1-1 to 1-12

[0096] Examples 1-1 to 1-12 were prepared by mixing all components except water on a Hobart mixer for 3 minutes at 1000 rpm. The amounts to be mixed for the individual examples are given in the below table 2. Visually homogeneous powders were obtained in every case.

[0097] The respective powder was then mixed with water in the amount indicated in the below table 2 on a Hobart mixer for 30 seconds at 1000 rpm.

[0098] Examples 1-1, 1-5, and 1-9 are comparative examples and are not according to the present invention. Examples 1-2 to 1-4, 1-6 to 1-8, and 1-10 to 1-12 are according to the present invention.

[0099] The resulting mixtures were tested as indicated above. The following table 2 shows the results.

TABLE-US-00002 TABLE 2 Composition of examples 1-1-1-12 and measured results (all dosages in g) Example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 OPC 1 35 33 31.5 29.75 OPC 2 35 33 31.5 29.75 Sand 65 65 65 65 65 65 65 65 MK 1 2 3.5 5.25 2 3.5 5.25 Plasticizer 0.1 0.2 0.35 0.1 0.2 0.35 Defoamer 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Water 13.5 13.5 13.5 13.5 12.8 12.8 12.8 12.8 Compressive strength 38 42 35 39 38 38 38 37 1 d [MPa] Compressive strength 59 68 66 71 61 64 66 71 28 d [MPa] Flexural strength 4.5 5.7 5.5 5.6 4.5 5.6 4.9 4.0 1 d [MPa] Flexural strength 28 d 7.2 9.6 8.1 9.5 8.6 10.3 9.2 10.1 [MPa] Capillary absorption 0.073 0.068 0.060 n.m. 0.046 0.032 0.023 n.m. [kg/m.sup.2h.sup.1/2] Example 1-9 1-10 1-11 1-12 OPC 2 35 33 31.5 29.75 Sand 65 65 65 65 MK 2 2 3.5 5.25 Plasticizer 0.1 0.2 0.35 Defoamer 0.01 0.01 0.01 0.01 Water 12.8 12.8 12.8 12.8 Compressive strength 1 d [MPa] 38 43 41 40 Compressive strength 28 d [MPa] 61 67 69 67 Flexural strength 7 d [MPa] 6.8 7.9 7.0 6.7 n.m.: not measured

[0100] It can be seen from the above table 2, that the addition of metakaolin leads to a general increase of compressive strength, especially after 28 days of curing. Also, the flexural strength is increased after 1d, 7d or 28d of curing.

[0101] It can also be seen from the above table 2 that the increase of dosage of metakaolin to 17.6 mass parts per 100 mass parts of cement does not lead to a significantly increased strength performance, and in some cases even to a decrease of strength performance, as compared to a dosage of metakaolin of 6 or 11 mass parts per 100 mass parts of cement (compare e.g. example 1-4 with examples 1-2 and 1-3).

[0102] The capillary absorption is reduced with increasing dosage of metakaolin.

[0103] There is thus an optimum of metakaolin dosage for the purpose of increasing the strength performance and optimizing the capillary absorption. All of which are important features for compositions to be used in the refurbishment of porous construction materials.

Example 2-1 to 2-5

[0104] Examples 2-1 to 2-5 were prepared in the same way as examples 1-1 to 1-12 above. The following table 3 shows an overview of the compositions.

[0105] Examples 2-4 and 2-5 are comparative examples and not according to the present invention. Examples 2-1 to 2-3 are according to the present invention.

[0106] The resulting mixtures were tested as indicated above. The following table 3 shows the results.

TABLE-US-00003 TABLE 3 Composition of examples 2-1-2-5 and measured results (all dosages in g) Example 2-1 2-2 2-3 2-4 2-5 CEM I 42.5 R 39 39 35 31 21 Sand 60 60 60 60 60 MK 1 1 5 9 19 MK 3 1 Defoamer 0.01 0.01 0.01 0.01 0.01 Water 9.5 9.3 10.5 12.2 20.4 Carbonation depth 1.2 2.0 1.8 2.2 13.5 [mm]

[0107] It can be seen from the above table 3 that the carbonation depth of a hardened composition C according to the present invention is 2 mm or below (examples 2-1 to 2-3). With an increasing content of metakaolin, the carbonation depth also increases, which is unwanted. At 29 mass parts of metakaolin per 100 mass parts of cement, the carbonation depth is higher than 2 mm (example 2-4), at 90 mass parts metakaolin per 100 mass parts of cement, the carbonation depth increases to an unacceptable high level of 13.5 mm (example 2-5).

Examples 3-1 to 3-4

[0108] Examples 3-1 to 3-4 were prepared in the same way as examples 1-1 to 1-12 above. The following table 4 shows an overview of the compositions. The amount of plasticizer was adjusted to generate wet mixes of the same workability.

[0109] Examples 3-1 to 3-4 are according to the present invention.

[0110] The resulting mixtures were tested as indicated above. The following table 4 shows the results.

TABLE-US-00004 TABLE 4 Composition of examples 3-1-3-4 and measured results (all dosages in g) Example 3-1 3-2 3-3 3-4 OPC 2 33 33 33 33 Sand 65.9 65.2 64.8 64.6 MK 1 1 1.7 2 2.2 Plasticizer 0.05 0.1 0.15 0.18 Defoamer 0.01 0.01 0.01 0.01 Water 13.5 13.5 13.5 13.5 Compressive strength 36.4 37.5 36.9 35.5 1 d [MPa] Flexural strength 6.1 7.1 6.1 6.4 1 d [MPa] Capillary absorption 0.062 0.05 0.045 0.046 [mm]

[0111] It can be seen from the above table 4 that the compressive strength and flexural strength of a hardened composition C of the present invention is highest where 5 mass parts of metakaolin are used per 100 mass parts of cement (example 3-2). The capillary absorption is lowest where 6 mass parts of metakaolin are used per 100 mass parts of cement (example 3-3).