Secondary ettringite type expanding agent and preparation method and application thereof

A technology of secondary calcium and expansion agent, which is applied in the field of material science and engineering science, can solve the problems of complex production process, consumption of natural resources, and high production cost of expansion agent, so as to protect the ecological environment, reduce shrinkage cracks, and improve internal stress status effect

Active Publication Date: 2011-08-31
HOHAI UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the currently used calcium sulfoaluminate expansion agent is produced by high-temperature treatment using pure raw materials such as alum and gypsum. Not only is the production process complicated, but it also consumes a large amount of natural resources, which increases the production cost of the expansion agent.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0022] The specific preparation method is: (1) will contain Al 2 o3 The pozzolanic material is mixed with calcareous material, gypsum and water, and then formed into green bodies or balls, which are naturally cured for 1 to 28 days, and cured in a curing cellar for 0.5 to 10 hours at 80°C to 90°C with dry heat. To 100°C-170°C, keep the temperature for 0.5-10 hours for dehydration and ettringite decomposition reaction, or after the formed green body or pellets stand still for 2-10 hours, autoclave at 120°C-190°C for 1 to 10 hours, and then dehydrated at 100°C for 0.5 to 10 hours, or to dehydrate the hydrothermally synthesized aluminosilicate material and its waste at 100°C for 0.5 to 10 hours; (2) 60 to 95 parts by weight The above materials are weighed with 5-40 parts by weight of anhydrite, and then mixed or ground to a particle size ≤ 80 μm, and then sent to an air mixer for homogenization to obtain a specific surface area greater than 200m 2 / kg powder is the secondary ett...

Embodiment 1

[0026] Embodiment 1: the preparation method of secondary ettringite type expansion agent

[0027] The following are parts by weight

[0028] (1) Weigh 20 parts of fly ash, 5 parts of lime, 1 part of gypsum and 12 parts of water, mix and stir, shape into green bodies or balls, and naturally cure for 1 to 28 days. Dry heat curing at 90°C for 0.5 to 10 hours, raise the temperature to 100°C to 170°C, and keep the temperature constant for 0.5 to 10 hours to carry out dehydration and ettringite decomposition reactions. Then weigh 60 parts of the above materials and 40 parts of anhydrous gypsum, mix and grind them and send them into an air mixer for homogenization, and the obtained powder with a particle size of ≤80 μm is the secondary ettringite-type expansion agent.

[0029] (2) Weigh 20 parts of coal gangue, 5 parts of lime, 1 part of gypsum and 12 parts of water, mix and stir, and shape it into green bodies or balls. Naturally cured for 0-28 days, in the curing cellar at 80 ℃ to...

Embodiment 2

[0037] Embodiment 2, the application example of secondary ettringite type expansion agent

[0038] (1) Application of the expansion agent of the present invention in self-leveling mortar

[0039] In this example, the cement is P·Ⅱ52.5; the fine sand has a fineness modulus of 1.9; the thickener is hydroxyethyl cellulose ether; the water reducing agent is the aliphatic The water reducing agent; the expansion agent is the secondary ettringite type expansion agent provided by the present invention.

[0040] Using a lime-sand ratio of 1:1.5, a water-cement ratio of 1:2.5, a superplasticizer dosage of 0.6% of the cement mass, and a thickener dosage of 0.3‰ of the cement mass, the dry powder secondary alum of the present invention The stone-type expansion agent is mixed with 6% equivalent cement mass (internal mixing). The performance of the freshly mixed self-leveling mortar is as follows: the self-expanding fluidity is 28cm, and the flow time in the Malanobis cone with the outlet...

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Abstract

The invention discloses a secondary ettringite type expanding agent and a preparation method and application thereof. The preparation method comprises the following steps of: stirring a pozzolanic material, a calcium material, plaster and water, forming into a blank or spheres, naturally curing, performing dry heating curing in a curing cell for 0.5 to 10 hours, raising the temperature to 100-170DEG C, and keeping the temperature for 0.5 to 10 hours for dehydration and ettringite decomposition reaction, or standing the formed blank or spheres for 2 to 10 hours, curing under steam pressure, and dehydrating for 0.5 to 10 hours, or dehydrating the thermally synthesized aluminosilicate material and wastes thereof at the temperature of higher than 100DEG C for 0.5 to 10 hours; and mixing and grinding 60 to 95 weight parts of material and 5 to 40 weight parts of anhydrous gypsum, or respectively grinding 60 to 95 weight parts of material and 5 to 40 weight parts of anhydrous gypsum and uniformly mixing to obtain powder of which the specific surface area is more than 200m<2> / kg, namely the secondary ettringite type expanding agent. The secondary ettringite type expanding agent can endow mortar and concrete with micro-expansion property, and improve the volume stability of the mortar and concrete.

Description

technical field [0001] The invention belongs to the technical field of material science and engineering science, and in particular relates to the preparation and application method of a secondary ettringite type expansion agent. Background technique [0002] A major defect of ordinary cement concrete products is volume shrinkage due to water loss and changes in temperature and humidity in the initial stage of setting and hardening. When the tensile stress generated by the restricted shrinkage exceeds the tensile strength of the concrete itself, the cement concrete members are prone to cracking. After cracking, the bearing capacity of the concrete decreases sharply. In addition, the durability of the concrete will be further deteriorated due to the infiltration of water, which will lead to corrosion of steel bars, structural damage, and reduce the performance of the concrete. The shrinkage and cracking of concrete has become an extremely common and serious problem in enginee...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B22/14
CPCC04B40/0039Y02W30/91C04B7/323C04B20/0076C04B22/143C04B7/12C04B18/0445C04B18/08C04B18/12C04B22/064C04B18/027C04B18/16
Inventor 蒋亚清胡飞龙顾越陈龙刘小艳
Owner HOHAI UNIV
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