WO2014079252A1 - Retarder suitable for quick setting and rapid hardening magnesium phosphate cement system and methods of use thereof - Google Patents

Abstract

A retarder suitable for the quick setting and rapid hardening magnesium phosphate cement system and methods of use thereof. The retarder is composed of one or more chloride salts and is used in four ways: 1) to prepare a solution on the spot; 2) to prepare a solution in advance; 3) to modify the magnesium phosphate cement by stiring on the spot; and 4) to modify the magnesium phosphate cement by stiring in advance.

Description

 Retarder for quick-setting fast-hardening magnesium phosphate cement system and using method thereof Technical field

The invention belongs to the field of preparation of magnesium phosphate cement-based composite materials, in particular to a novel retarder suitable for use in a magnesium phosphate cement system and a method for using the same.

Background technique

Since the 1980s, the rapid development of economic construction has promoted the vigorous development of the transportation industry and put forward higher requirements for road construction. Due to heavy traffic loads, environmental conditions and improper use and maintenance, the newly constructed high-grade concrete pavement has also suffered a certain degree of damage. In order to reduce the economic loss caused by the traditional long-term repairing construction, there is an urgent need for a quick-hardening and early-strength repairing material. As a new type of cementitious material, magnesium phosphate cement has been widely used in the United States and other Western countries in the 1980s because of its fast, hard and early strength. It is widely used in concrete such as highways, bridge decks and airstrips. Rapid repair of pavements, and industrial plant floors. However, the main action phase in the magnesium phosphate cement system - magnesium oxide and phosphate react very strongly after contact with water. When the retarder is not added or the retarder is mixed for a short time, the magnesium phosphate cement is mixed from The final setting time is extremely short and it is difficult to meet the construction operation and process requirements. Therefore, in order to solve this situation, the development of a retarder suitable for the magnesium phosphate system is a prerequisite for the rapid, hard, and early strength of the magnesium phosphate cement system in repairing construction.

At present, many scholars at home and abroad have studied different types of retarders for magnesium phosphate systems, among which borax and boric acid have the best effect. However, the retardation effects of these two and other existing retarders are still very limited, and they all have a common problem, that is, the existing retarder greatly inhibits the early strength development of magnesium phosphate cement, and When the temperature is high, the retarder basically loses its retarding effect. Therefore, we need a new retarder that has a stronger retarding effect, a good retarding effect at higher temperatures, and less inhibition of early strength development.

technical problem

The invention solves the technical problems that the setting time of the magnesium phosphate cement repairing system is extremely short, and can not meet the requirements of the operation time during the actual repairing construction. On the one hand, the retarder can not only prolong the setting time of the magnesium phosphate repair system at normal temperature, but also has a strong retarding effect in a high temperature environment; on the other hand, the retarder can not only ensure the magnesium phosphate cement The early strength of the sample also improved its late strength to some extent. The invention also provides four methods for using the retarder, the four methods of use are simple and quick to use in preparing the magnesium phosphate cement repairing material, and different retarders also have different effects, changing the magnesium phosphate The current status of the system using solid retarders for a long time.

Technical solution

 In order to solve the above technical problems, the technical solution adopted by the present invention is:

 A new retarder is used, which consists of one or several chlorine salts.

The chloride salt may be magnesium chloride hexahydrate MgCl ₂ ·6H ₂ O, sodium chloride NaCl, potassium chloride KCl, calcium chloride CaCl ₂ , copper chloride CuCl ₂ , ferric chloride FeCl ₃ , ferrous chloride FeCl _2. A complex of one or more of a chloride salt such as barium chloride BaCl ₂ or tetrabutylammonium chloride C ₁₆ H ₃₆ ClN, and is not limited to the above chloride salt.

 There are four main methods of using this retarder:

The first type, the existing solution, according to the actual construction requirements, before the construction, using the retarder and water of the invention to prepare a uniform clear solution, the solution concentration is maintained at 5%-40%, and then directly used in the magnesium phosphate cement system. ;

 The second type, the pre-dispensing solution, according to the actual construction requirements, using the retarder of the invention and water to prepare a uniform clear solution, the mass concentration of the solution is maintained at 5%-40%, sealed and allowed to stand in the magnesium phosphate cement system;

Thirdly, the currently mixed modified magnesium phosphate cement, according to the actual construction requirements, before the construction, using the retarder of the invention, is added to the magnesium phosphate cement as a solid powder, and the ratio of the retarder to the magnesium oxide In 2%-20% , mix well, then add water to use;

The fourth type is premixed modified magnesium phosphate cement. When the magnesium phosphate cement is produced, the retarder of the invention is uniformly mixed with magnesium oxide and phosphate, and the ratio of the retarder to the magnesium oxide is

 2%-20%

 Prepared as modified magnesium phosphate cement, and then directly added with water.

Beneficial effect

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

1. When the retarder of the invention is used in a magnesium phosphate cement system, the retarding effect is excellent. The retarder not only greatly prolongs the setting time of the magnesium phosphate repair system at normal temperature, but also has a strong retarding effect in a high temperature environment.

2. When the retarder is used in the magnesium phosphate cement system, the retardation time can be up to 54 minutes, and the retardation time can be arbitrarily adjusted within 3 to 54 minutes. Compared with the retarding effect of the conventional retarder existing under the same conditions, the retarder is more than 1.5-2 times of the retarder already used by the retarder of the present invention.

3. When the retarder of the invention is used in a magnesium phosphate cement system, the mechanical properties of the magnesium phosphate cement can be improved. The retarder has little inhibitory effect on the early strength development of the magnesium phosphate cement system, and can promote the development of the late strength of the magnesium phosphate cement in a certain degree. The major drawbacks of existing retarders (such as borax) to inhibit the early strength development of magnesium phosphate cement are completely avoided. Long-term tests have also shown that the strength of the magnesium phosphate cement sample incorporating the appropriate amount of the retarder of the invention is increased.

4. When the retarder of the invention is used in a magnesium phosphate cement system, the preparation process is simple. When the existing blending method and the ready-mixing method are used, the retarder preparation of the invention is simple and quick, and the retarding effect is remarkable. When the pre-mixing and pre-mixing modes are selected, the retarder of the invention is a uniform clear solution, which is not volatile. It can be stored for a long time without affecting its retarding effect.

Embodiments of the invention

The invention will be further elucidated below in conjunction with the embodiments.

The invention is a retarder, the retarder is mainly magnesium chloride hexahydrate (MgCl ₂ • 6H ₂ O), sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl ₂ ), chlorine Copper chloride (CuCl ₂ ), ferric chloride (FeCl ₃ ), ferrous chloride (FeCl ₂ ), barium chloride (BaCl ₂ ), tetrabutylammonium chloride (C ₁₆ H ₃₆ ClN) and other chloride salts One or several complexes, and is not limited to the above chloride salts. Its role is mainly to control the setting time of the magnesium phosphate cement system, so as to facilitate molding on the construction site. Since the reaction of magnesium oxide and phosphate is an acid-base neutralization reaction, the reaction is severe. In order to facilitate the molding operation, a retarder is added during the test to adjust the setting time of the magnesium phosphate system. When preparing the magnesium phosphate cement sample, the retarder can be prepared in the following four ways, and then fully stirred with the magnesium phosphate cement component, the stirring time is not less than 1 minute, and the mixture is uniformly molded and then injected into the mold.

The first type, the existing solution, according to the actual construction requirements, before the construction, the retarder is mixed with water to form a uniform clear solution, the solution concentration is maintained between 5% and 40%, and then directly used for the magnesium phosphate cement. In the system;

The second type, the pre-dispensing solution, according to the actual construction requirements, using the retarder of the invention and water to prepare a uniform clear solution, the solution concentration is maintained between 5% and 40%, the seal is allowed to stand, and then used for the magnesium phosphate cement. In the system;

Thirdly, the currently mixed modified magnesium phosphate cement, according to the actual construction requirements, before the construction, using the retarder of the invention, is added to the magnesium phosphate cement as a solid powder, and the ratio of the retarder to the magnesium oxide Between 2% and 20%, mix well, then add water;

The fourth type, ready-mixed modified magnesium phosphate cement, in the production of magnesium phosphate cement, the retarder of the present invention is uniformly mixed with magnesium oxide and phosphate, and the mass ratio of retarder to magnesium oxide is 2%-20 Between the %, the modified magnesium phosphate cement is prepared and then directly added with water.

The type and amount of chloride salt are selected according to the requirements of the construction process for the retardation time and strength development and the ambient temperature during construction.

Comparative example 1:

In the examples, it was found that the magnesium phosphate cement system could not be formed without the addition of a retarder. Therefore, doped borax was selected as a comparative example. In the comparative example, the molar ratio of magnesium oxide/potassium dihydrogen phosphate was 5:1, and the borax/magnesium oxide mass ratio was 0.05.

The test results showed that the initial setting time of the sample was 3 min, the final setting time was 6 min, the strength at 3 h was 20.16 MPa, and the strength at 1 d was 31.47 MPa.

Example 1:

The invention provides a retarder for preparing a magnesium phosphate cement sample, and the chlorine salt is selected from sodium chloride (NaCl). According to the first method of use, sodium chloride and water are mixed and stirred according to the mass ratio of magnesium chloride/water quality=14%. Clarify the solution evenly.

Weigh magnesium oxide (595g) and Potassium dihydrogen phosphate powder (405 g) was uniformly mixed, and 198 g of the retarder prepared above was immediately added, and stirred for 1 min to prepare a uniform magnesium phosphate cement paste. A part of the mold was poured into a mold of 30 mm * 30 mm * 30 mm, and placed in a temperature of 20 ± 2 ° C, relative humidity of 60 ± 5% in the environment to naturally maintain; another part of the slurry for the condensation time test. Coagulation time test test reference GB/T1346-2001 "Ceramic standard consistency water consumption condensation time stability test method", compressive strength test according to GB/T 17671-1999 "Test method for strength of cement mortar (ISO method)".

The test results showed that the initial setting time of the magnesium phosphate cement paste added with the chlorine salt retarder was 7 min, the final setting time was 12 min, the 3 h strength was 24.97 MPa, and the 1 d strength was 35.71 MPa.

Example 2:

The magnesium phosphate cement sample is prepared by using the retarder of the invention, and the chloride salt is selected from magnesium chloride hexahydrate (MgCl ₂ • 6H ₂ O). According to the second method of use, magnesium chloride hexahydrate and water are used according to the mass of magnesium chloride/water quality=0.14. Mix and stir into a homogeneous clear solution, and seal to stand for use.

Magnesium oxide (595 g) and potassium dihydrogen phosphate powder (405 g) were weighed uniformly, and the retarder (198 g) prepared above was added and stirred for 1 min to prepare a uniform magnesium phosphate cement paste. A part of the mold was poured into a mold of 30 mm * 30 mm * 30 mm, and placed in a temperature of 20 ± 2 ° C, relative humidity of 60 ± 5% in the environment to naturally maintain; another part of the slurry for the condensation time test. Coagulation time test test reference GB/T1346-2001 "Ceramic standard consistency water consumption condensation time stability test method", compressive strength test according to GB/T 17671-1999 "Test method for strength of cement mortar (ISO method)".

The test results showed that the initial setting time of the magnesium phosphate cement paste added with the chlorine salt retarder was 6 min, the final setting time was 13 min, the 3 h strength was 25.4 MPa, and the 1 d strength was 39.7 MPa.

Example 3:

The invention provides a retarder for preparing a magnesium phosphate cement sample, and the chloride salt is selected from potassium chloride (KCl). According to the third method of use, according to the mass of potassium chloride / mass of magnesium chloride / mass of potassium dihydrogen phosphate = 0.05:1: In the ratio of 0.68, the three powders were mixed and stirred uniformly, and then water containing 0.17 by mass of magnesium oxide and potassium dihydrogen phosphate was added and stirred for 1 minute to prepare a uniform magnesium phosphate cement paste. A part of the mold was poured into a mold of 30 mm * 30 mm * 30 mm, and placed in a temperature of 20 ± 2 ° C, relative humidity of 60 ± 5% in the environment to naturally maintain; a part of the slurry for the condensation time test. Coagulation time test test reference GB/T1346-2001 "Ceramic standard consistency water consumption condensation time stability test method", compressive strength test according to GB/T 17671-1999 "Test method for strength of cement mortar (ISO method)".

Test results: The initial setting time of the magnesium phosphate cement paste added with the chloride salt retarder was 7 min, the final setting time was 13 min, the 3 h intensity was 21.32 MPa, and the 1d intensity was 31.42. MPa.

The present invention is not limited by the above-described embodiments, and the above-described embodiments and the description are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention. Improvements are within the scope of the claimed invention.

Claims (6)

1.  A retarder suitable for a quick-setting fast-hardening magnesium phosphate cement system, characterized in that the retarder is composed of one or several chlorine salts.
2. The retarder for a fast setting fast hard magnesium phosphate cement system according to claim 1, wherein the chlorine salt comprises: magnesium chloride hexahydrate MgCl ₂ • 6H ₂ O, sodium chloride NaCl, potassium chloride. KCl, calcium chloride CaCl ₂ , copper chloride CuCl ₂ , ferric chloride FeCl ₃ , ferrous chloride FeCl ₂ , barium chloride BaCl ₂ , tetrabutylammonium chloride C ₁₆ H ₃₆ ClN, and are not limited to the above Chloride salt.
3. A method for using a retarder suitable for a quick-setting fast-hardening magnesium phosphate cement system according to claim 1, characterized in that the first use of the retarder is: a ready-to-use solution, according to actual construction requirements Before the construction, the retarder is mixed with water to form a uniform clear solution, and the solution concentration is maintained at 5%-40%, and then directly used in the magnesium phosphate cement system.
4. A method for using a retarder suitable for fast setting fast hard magnesium phosphate cement system according to claim 1, characterized in that the second usage of the retarder is: pre-dispensing solution, according to actual construction requirements The retarder is mixed with water to form a uniform clear solution, the mass concentration of the solution is maintained at 5%-40%, the seal is allowed to stand, and then used in the magnesium phosphate cement system.
5. A method for using a retarder suitable for a quick-setting fast-hardening magnesium phosphate cement system according to claim 1, wherein the third use of the retarder is: fresh-mixed magnesium phosphate cement, According to the actual construction requirements, before the construction, the retarder is used in the form of a solid powder and added to the magnesium phosphate cement. The mass ratio of the retarder to the magnesium oxide is between 2% and 20%, and the mixture is uniform, and then water is added. use.
6. A method for using a retarder suitable for a quick-setting quick-hardening magnesium phosphate cement system according to claim 1, characterized in that the fourth usage of the retarder is: premixed modified magnesium phosphate cement, In the production of magnesium phosphate cement, the retarder of the invention is uniformly mixed with magnesium oxide and phosphate, and the mass ratio of the retarder to the magnesium oxide is 2%-20%, and the modified magnesium phosphate cement is prepared, and then Use water directly.