Liquid accelerator for the setting of concrete mixtures

• US 4,504,315 A
• Filed: 02/22/1984
• Issued: 03/12/1985
• Est. Priority Date: 02/24/1983
• Status: Expired due to Fees

• Current Assignee: Dynamit Nobel AG
• Original Assignee: Dynamit Nobel AG
• Inventors: Vogel, Gunter, Hass, Hansjurgen, Deneke, Klaus, Allemann, Kurt
• Primary Examiner(s): Poer, James
• Application Number:
  US06/582,625
• Time in Patent Office: 384 Days
• Field of Search: 106/89, 106/97, 106/315
• US Class Current: 106/713
• CPC Class Codes: C04B 22/00 Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators , shrinkage compensating agents
• CPC Class Codes: C04B 22/062 of the alkali or alkaline-earth metals
• CPC Class Codes: C04B 22/10 containing carbon in the anion
• CPC Class Codes: C04B 28/04 Portland cements

Abstract

The present invention relates to liquid accelerators for the setting of concrete mixtures. These accelerators have a long shelf life even in higher concentrations than the liquid accelerators known heretofore and, within the defined concentrations, produce no precipitation. The new accelerators are characterized by containing only potassium aluminate, potassium carbonate and potassium hydroxide in a defined range. They can be used in any known hydraulic binding agents, they shorten the set time of these binding agents, and they improve the compressive strength of the products made with them.

Claims

1. A liquid accelerator for setting concrete mixtures comprising an aqueous solution of potassium aluminate, potassium hydroxide and potassium carbonate wherein

(a) the ratio of moles of K₂ O not bound to potassium carbonate to moles of Al₂ O₃ is between about 1.1 and 1.4;

(b) the content of water as a solvent is such that the ratio of moles of water to moles of Al₂ O₃ is between about 9.5 and 20; and

(c) the potassium carbonate content is between about 0.1 and 3.4 mole-%.

2. The accelerator of claim 1 wherein the ratio of moles of K₂ O not bound to potassium carbonate, to moles of Al₂ O₃ is between 1.25 and 1.37.

3. The accelerator of claim 2 wherein the ratio of moles of water to moles Al₂ O₃ is between 14 and 17.

4. The accelerator of claim 1 wherein the ratio of moles of water to moles Al₂ O₃ is between 14 and 17.

5. In a mortar or concrete mixture based on Portland cement, the improvement comprising an effective amount of the liquid accelerator of claim 1 to accelerate the setting of the mixture.

6. The mixture of claim 5 containing between 2 and 6% of the accelerator based on the weight of the cement.

7. In a mortar or concrete mixture with a liquid accelerator according to claim 1, the improvement comprising limiting the loss of compressive strength at the age of 28 days to no more than 15% compared with the same mixture without said accelerator.