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 wherein the hydrophobic resin having dispersible particles of the hydrophobic resin having a mean particle size in a range of 0.4-0.6 micrometer; the mean particle size referring to an average size of resin particles before addition to the concrete mixture; the concrete mixture having more than 210 grams of the hydrophobic resin per cubic meter of the concrete mixture and up to 840 grams of the hydrophobic resin per cubic meter of the concrete mixture, and wherein at least 90 wt % of the hydrophobic resin is dissolved in the concrete mixture.

2. 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.

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

4. 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, 0.210-0.840 kilogram of the hydrophobic resin per cubic meter of concrete mixture, and 0.005-1 parts by weight of an anionic surface-active compound.

5. A concrete having a density of 250-2200 kilograms/cubic meter 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.

6. A pumpable aqueous concrete mixture according to claim 1, wherein the hydrophobic resin has dispersible particles that have a mean particle size of 0.5 micrometer.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Referring now to the figures, which are exemplary embodiments.

(2) 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.

(3) 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.

(4) FIG. 3 shows the cross-section of FIG. 2 in higher magnification.

(5) FIG. 4 shows the adhesion at the interface between the aggregate material and the aerated concrete at 200× magnification.

(6) FIG. 5 shows the adhesion at the interface between the aggregate material and the aerated concrete at 400× magnification.

(7) FIG. 6 shows the adhesion at the interface between the aggregate material and the aerated concrete at 100× magnification

EXAMPLES

Example 1

(8) 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™ tenside and 40% of a tenside sold under the trade name Darex AEA™ tenside, 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 molds. During the casting test, no settlements should be obtained. Specimens of the casted concrete were then analyzed 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 resins are all available on the market as resin dispersions, and the amount added denotes the amount of resin added.

(9) TABLE-US-00001 TABLE 1 Average particle Resin size (μm) 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

(10) 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™ tenside and 40% of a tenside sold under the trade name Darex AEA™ tenside, 0.420 kg resin sold under the trade name Aquataq XR4343™ resin 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:

(11) Compressive strength: 1.9 MPa

(12) Flexural strength: 0.2 MPa

(13) Modulus of elasticity in compression: 0.7 MPa

(14) Shrinkage after 14 days: 0.21%

(15) Shrinkage after 21 days: 0.71%

(16) Shrinkage after 35 days: 2.95%

(17) Shrinkage after 63 days: 4.78%

(18) While the present invention has been described in accordance with preferred compositions and embodiments, it is to be understood that certain substitutions and alterations may be made thereto without departing from the spirit and scope of the following claims.