METHODS FOR THE CONTROL OF SHRINKAGE OF CEMENTITIOUS COMPOSITIONS AND CEMENTITIOUS GROUTS HAVING CONTROLLED SHRINKAGE

Abstract

A method for the control of the shrinkage of cementitious materials, the method comprising the steps of providing a cementitious material, adding aluminium powder to the cementitious material, adding calcium oxide or magnesium oxide to the cementitious material, and adding a shrinkage reducing agent which is an organic molecule to the cementitious material. Cementitious grouts including aluminium powder, calcium oxide or magnesium oxide, and a shrinkage reducing agent which is an organic molecule.

Claims

1. A method for the control of the shrinkage of cementitious materials, the method comprising the steps of (i) providing a cementitious material, (ii) adding aluminium powder to the cementitious material, (iii) adding calcium oxide or magnesium oxide to the cementitious material, (iv) adding a shrinkage reducing agent which is an organic molecule to the cementitious material, wherein the cementitious material has a density of not less than 800 kg/m.sup.3 after hardening.

2. A method as claimed in claim 1, wherein aluminium powder, calcium oxide or magnesium oxide, and shrinkage reducing agent which is an organic molecule are added to a dry cementitious material.

3. A method as claimed in claim 1, wherein aluminium powder, calcium oxide or magnesium oxide, and/or shrinkage reducing agent which is an organic molecule are added together with any mixing water.

4. A method as claimed in claim 1, wherein the cementitious material comprises a cementitious binder, the cementitious binder comprising cement and slag.

5. A method as claimed in claim 4, wherein the weight ratio of slag relative to the total dry weight of cementitious binder is at least 10 w %.

6. A method as claimed in claim 1, wherein the aluminium powder has a particle size D50 in the range of 0.1-45 m.

7. A method as claimed in claim 1, wherein the calcium oxide or magnesium oxide has a particle size D50 in the range of 10-50 m.

8. A method as claimed in claim 1, wherein the aluminium powder is added in an amount of 0.0001-0.01 w % relative to the weight of cementitious binder present in the cementitious material.

9. A method as claimed in claim 1, wherein the calcium oxide or magnesium oxide is added in an amount of 1-5 w % relative to the weight of cementitious binder present in the cementitious material.

10. A method as claimed in claim 1, wherein the shrinkage reducing agent which is an organic molecule is added in an amount of 0.1-2 w % relative to the weight of cementitious binder present in the cementitious material.

11. A method as claimed in claim 1, wherein the shrinkage reducing agent which is an organic molecule is selected from glycols, alkyl ethers of polyalkylene glycols, polyols, alkoxylated polyols, alkylated alkanolamines, and carboxylic acid esters of polyalkylene glycols.

12. A cementitious grout comprising or consisting of (in each case relative to the total dry weight of the cementitious grout) a) 10-80 w % of a cementitious binder, the cementitious binder comprising cement and slag, b) 0.0001-0.01 w % of aluminium powder, c) 0.3-2 w % of calcium oxide or magnesium oxide, d) 0.03-1 w % of a shrinkage reducing agent which is an organic molecule, e) 10-80 w % relative to the dry weight of the grout of at least one aggregate and/or filler, f) 0.001-0.1 w % of azodicarbonamide, and g) further additives.

13. The cementitious grout according to claim 12, wherein the cementitious binder comprises or consists of 5-95 w % of Portland cement and 5-95 w % of slag in each case relative to the dry weight of the cementitious binder.

14. The cementitious grout according to claim 12, wherein the cementitious binder comprises or consists of (in each case relative to the dry weight of the cementitious binder) i) 5-50 w % of Portland cement, ii) 5-50 w % of slag, iii) 1-5 w % of silica fume, iv) 0.5-3 w % of micro silica, and v) 0.1-1 w % of calcium hydroxide.

15. An admixture for cementitious compositions the admixture comprising aluminium powder, calcium oxide or magnesium oxide, and a shrinkage reducing agent which is an organic molecule.

Description

EXAMPLES

Example 1

[0090] Cementitious grout materials were prepared by thoroughly mixing the raw materials as indicated in below table 1 for 3 minutes on a laboratory mixer. Mixes were visually homogeneous. Examples 1 and 2 are comparative examples not according to the present invention. Examples 3 and 4 are inventive examples.

TABLE-US-00001 TABLE 1 compositions of examples (all numbers relate to w %) Example 1 2 3 4 CEM I 52.5 R 24 24 24 24 Slag*.sup.1 10.5695 10.5695 10.5695 10.5695 Silica fume*.sup.2 3 3 3 3 Micro silica*.sup.3 1.9 1.9 1.9 1.9 Ca(OH).sub.2 0.13 0.13 0.13 0.13 Sand*.sup.4 59 58.7 58.7 58.7 Aluminium 0.0005 0 0.0005 0.0005 powder*.sup.5 CaO*.sup.6 1 1 1 0 MgO*.sup.7 0 0 0 1 Organic SRA*.sup.8 0 0.3 0.3 0.3 Additives*.sup.9 0.4 0.4 0.4 0.4 *.sup.1ground granulated blast furnace slag (Blaine fineness 4500 cm.sup.2/g) *.sup.2BET surface 18-22 m.sup.2/g *.sup.3particle size D50 100 m *.sup.4particle sizes 0.1-0.7 mm, 0.6-1 mm, 1-2 mm, 2-3 mm *.sup.5particle size D50 8 m *.sup.6Lime CL-90 Q (<7% sieve residue at 90 m) *.sup.7particle size D50 15 m *.sup.8fatty acid ester of a mixed polyethylene/polypropylene glycol *.sup.9mixture of defoamer, superplasticizer, thickener

[0091] For the preparation of liquid grouts, the respective powders of examples 14 were slowly added to the mixing water within 3 minutes in a 3-L Hobart mixer. Water was used in an amount to give a water to powder weight ratio of 0.075. Mixing was then continued for 2 minutes at high speed. The liquid grout compositions were then immediately used for the following testing.

[0092] Dimensional stability was tested according to standard EN 12617-4. Fresh mortar expansion was measured according to standard ASTM C827. Autogenous shrinkage was measured according to standard ASTM C1698. All measurements were done after the time indicated in the below table 2.

[0093] The following table 2 gives an overview of the results.

TABLE-US-00002 TABLE 2 results measured Example 1 2 3 4 Dimensional stability +1.15 +0.9 n.m. +0.007 (24 h) [mm/m] Dimensional stability 0.006 0.018 n.m. 0.006 (7 d) [mm/m] Fresh mortar expansion +0.06 0.33 0 n.m. (1 h) [%] Fresh mortar expansion +0.6 0.53 +0.6 n.m. (24 h) [%] Autogenous shrinkage 0.29 0.144 0.130 n.m. (1 d) [strain] Autogenous shrinkage 0.42 0.214 0.191 n.m. (4 d) [strain] Bulk density 2367 2375 2370 2369 [kg/m.sup.3] n.m.: not measured positive values indicate expansion, negative values indicate shrinkage

[0094] It can be seen from the above examples that inventive compositions show improved dimensional stability (cf examples 1 and 2 with example 4). It can also be seen that inventive compositions show good expansion in the fresh state and less autogenous shrinkage (cf examples 1 and 2 with example 3).

Example 2

[0095] Cementitious grout materials were prepared in the same way as in example 1 by thoroughly mixing the raw materials as indicated in below table 3 for 3 minutes on a laboratory mixer. Mixes were visually homogeneous. Examples 5-8 are inventive examples.

TABLE-US-00003 TABLE 3 compositions of examples (all numbers relate to w %) Example 5 6 7 8 CEM I 52.5 R 24 24 24 24 Slag*.sup.1 10.55 10.5695 10.5695 10.5698 Silica fume*.sup.2 3 3 3 3 Micro silica*.sup.3 1.9 1.9 1.9 1.9 Ca(OH).sub.2 0.13 0.13 0.13 0.13 Sand*.sup.4 58.67 58.7 58.7 58.695 Aluminium powder*.sup.5 0.05 0.0005 0.0005 0.0002 CaO*.sup.6 1 1 1 1 Organic SRA*.sup.8 0.3 0.3 Organic SRA*.sup.10 0.3 Organic SRA*.sup.11 0.3 Additives*.sup.9 0.4 0.4 0.4 0.4 ADC*.sup.12 0.005 *.sup.1ground granulated blast furnace slag (Blaine fineness 4500 cm.sup.2/g) *.sup.2BET surface 18-22 m.sup.2/g *.sup.3particle size D50 100 m *.sup.4particle sizes 0.1-0.7 mm, 0.6-1 mm, 1-2 mm, 2-3 mm *.sup.5particle size D50 8 m *.sup.6Lime CL-90 Q (<7% sieve residue at 90 m) *.sup.8fatty acid ester of a mixed polyethylene/polypropylene glycol *.sup.9mixture of defoamer, superplasticizer, thickener *.sup.10glycerine (99% purity) *.sup.11polyethylene glycol (Mw appr. 500 g/mol) *.sup.12ADC: azodicarbonamide (CAS 123-77-3)

[0096] Liquid grouts were prepared in the same way as in example 1 with the respective powders of examples 5-8. Tests were done as described in example 1.

[0097] The following table 4 gives an overview of the results.

TABLE-US-00004 TABLE 4 results measured Example 5 6 7 8 Fresh mortar expansion +11 +0.23 0 +0.2 (1 h) [%] Fresh mortar expansion +11 +0.6 +0.67 +0.87 (24 h) [%] Autogenous shrinkage n.m. 0.13 0.34 0.16 (1 d) [strain] Bulk density 2386 2363 2368 2385 [kg/m.sup.3] n.m.: not measured positive values indicate expansion, negative values indicate shrinkage