HYDROPHOBIC CONCRETE MIXTURE

Abstract

The pumpable aqueous concrete mixture has an air pore volume of 10-85 volume-%, that includes a hydrophobic resin at least partially soluble in the concrete mixture and optionally an aggregate material.

Claims

1. A pumpable aqueous concrete mixture having an air pore volume of 10-85 volume-%, comprising a hydrophobic resin at least partially soluble in the concrete mixture, and an aggregate material.

2. The concrete mixture according to claim 1, wherein the hydrophobic resin comprises dispersible particles of the resin having a mean particle size of less than 0.7 m.

3. The concrete mixture according to claim 1, wherein the hydrophobic resin comprises dispersible particles of the resin having a mean particle size in the range of 0.4-0.6 m.

4. The concrete mixture according to claim 1 wherein the concrete mixture comprises 210-840 g of the hydrophobic resin per m.sup.3 of concrete mixture.

5. The concrete mixture according to claim 1, wherein the water to cement weight ratio in the concrete mixture is in the range of 0.40 to 0.80.

6. The concrete mixture according to claim 1, wherein the air pore volume is in the range of 18-75 volume %.

7. The concrete mixture according to claim 1, wherein the concrete mixture comprises: 100 parts by weight of cement, 35-80 parts by weight of water, 0-500 parts by weight of an aggregate material, 0.20-0.85 kg of the hydrophobic resin per m.sup.3 of concrete mixture, and 0.005-1 parts by weight of an anionic surface active compound.

8. A concrete having a density of 250-2200 kg/m.sup.3 and an air pore volume in the range of 15-90 volume-%, wherein the concrete is obtained by curing a concrete mixture according to claim 1.

9. Use of a concrete mixture according to claim 1, for casting an aerated concrete having a density in the range of 250-2200 kg kg/m.

10. Use of a dispersible hydrophobic resin when producing a pumpable, aqueous concrete mixture, said hydrophobic resin being at least partially soluble in the concrete mixture and having a particle size of less than 0.7 m.

11. A method for producing a pumpable aqueous concrete mixture having an air pore volume of 10-85 volume-% in a concrete mixer, the method comprising the following steps: a) providing water, 2-40 weight-% of a total amount of cement, a dispersible hydrophobic resin at least partially soluble in the concrete mixture and having a particle size of less than 0.7 m; b) agitating the added ingredients while entraining air to a homogenous, stable, air-containing mixture wherein the resin is at least partially dissolved in the mixture; and c) adding in one or more steps or continuously during mixing the remaining 60-98 weight-% of the total amount of cement.

12. The method according to claim 11, wherein the step a) further comprises providing an aggregate material to the mixer.

13. A method for producing concrete having a density of 250-2200 kg/m3 and an air pore volume in the range of 15-90 volume-%, wherein the concrete is obtained by casting a pumpable, aqueous concrete mixture obtained according to claim 11 and subsequently curing the concrete mixture.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0073] Referring now to the figures, which are exemplary embodiments.

[0074] FIG. 1 shows an aerated concrete comprising low density aggregate material cast from the concrete mixture of the present invention. To the left of the black line a fractured surface is shown. To the right of the black line sawn surface is shown.

[0075] FIG. 2 shows a sawn cross-section of a particulate of a low density aggregate material, surrounded by an aerated concrete cast from the concrete mixture according to the invention.

[0076] FIG. 3 shows the cross-section of FIG. 2 in higher magnification.

[0077] FIG. 4 shows the adhesion at the interface between the aggregate material and the aerated concrete at 200 magnification.

[0078] FIG. 5 shows the adhesion at the interface between the aggregate material and the aerated concrete at 400 magnification.

[0079] FIG. 6 shows the adhesion at the interface between the aggregate material and the aerated concrete at 100 magnification

EXAMPLES

Example 1

[0080] For producing aerated concrete having a wet density of 500 kg/m.sup.3, the following step-wise procedure took place. Into a laboratory mixer having a volume of 40 liters, 8.1 kg of water, a tenside mixture comprising a mix of 60% of a tenside sold under the trade name Dowfax 3B2 and 40% of a tenside sold under the trade name Darex AEA, a resin as indicated below (added as a dispersion unless otherwise noted) and 4.1 kg of Portland cement was supplied. The compounds were stirred at a speed of 380 rpm for 25 s and resulted in a aerated concrete mixture. Then 7.6 kg of Portland cement was added continuously to the mixer within 70 s during agitation at a speed of 166 rpm. The agitation continued for further 320 s until a concrete mixture was obtained. The concrete mixture was the subjected to pouring test to test the stability during handling, casting test, where the concrete mixture is cast on different bases such as water, dry sand, absorbing bases, steel moulds. During the casting test, no settlements should be obtained. Specimens of the casted concrete were then analysed in a microscope. The shape of the air pores, the size of the air pores, the fracture surface, the pore wall stiffness and roundness is analyzed and given a pass or fail mark. In the following table, the samples marked pass have passed all the tolerance in all of the above mentioned analyzes. The samples marked fail have failed at least one of the above mentioned analyzes. The results are presented in Table 1. The added resin are all available on the market as resin dispersions, and the amount added denotes the amount of resin added.

TABLE-US-00001 TABLE 1 Average particle Resin size (m) Amount Pass/Fail Aquatac XR4343 0.5 8.4 g Fail 0.5 16.8 g Pass 0.5 21 g Pass Aquatac XR4316 <0.5 8.4 g Fail <0.5 10.8 g Fail <0.5 16.8 g Fail Aquatac XR4324 <0.5 8.4 g Fail DC 84 N/A 8.4 g Fail N/A 12.3 g Fail N/A 17.3 g Fail DLP 212 N/A 8.4 g Fail N/A 15 g Fail DLP 2141 N/A 8.4 g Fail N/A 15 g Fail Surfonyl 2502 N/A 10.2 Fail

Example 2

[0081] For producing aerated concrete having a wet density of 500 kg/m.sup.3, the following step-wise procedure took place. Into a concrete mixer, 202.5 kg of water, 2.750 kg of a tenside mixture comprising 60% of a tenside sold under the trade name Dowfax 3B2 and 40% of a tenside sold under the trade name Darex AEA, 0.420 kg resin sold under the trade name Aquataq XR4343 and 103.0 kg of Portland cement was supplied. The compounds were stirred at a speed of 380 rpm for 25 s and resulted in a aerated concrete mixture. Then 191.25 kg of Portland cement was added continuously to the mixer within 70 s during agitation at a speed of 166 rpm. The agitation continued for further 320 s until a concrete mixture was obtained. The mixture was the poured into steel forms and allowed to cure at room temperature. After 28 days, the compressive strength were measured according to SS-EN 12390-3:2009, the flexural strength according to SS-EN 12390-5:2009, the shrinkage according to SS 137215, and the modulus of elasticity in compression according to SS 137232:2005. The results from the measurements are shown below:

Compressive strength: 1.9 MPa
Flexural strength: 0.2 MPa
Modulus of elasticity in compression: 0.7 MPa
Shrinkage after 14 days: 0.21
Shrinkage after 21 days: 0.71
Shrinkage after 35 days: 2.95
Shrinkage after 63 days: 4.78