阅读说明：本技术 一种适用于高原寒冷地区的双组份无碱速凝剂及使用方法 (Double-component alkali-free accelerator suitable for plateau cold regions and use method thereof ) 是由 王家赫 谢永江 冯仲伟 谭盐宾 仲新华 李享涛 渠亚男 于 2021-02-01 设计创作，主要内容包括：本发明属于混凝土外加剂技术领域,特别涉及一种适用于高原寒冷地区的双组份无碱速凝剂及使用方法,所述双组份无碱速凝剂包括快硬组分A和促凝组分B,二者质量比为70～80:20～30。其中,快硬组分A为粉体材料,主要由铝酸三钙(C-(3)A)、氢氧化钙(CH)、半水石膏(CaSO-(4)﹒0.5H-(2)O)组成；促凝组分B为液体材料,主要由聚合硫酸铝(PAS)、三乙醇胺(TEOA)、硫酸锂(Li-(2)SO-(4))、乳酸(HL)和水组成。本发明通过快硬组分与促凝组分协同作用,解决了高原低温环境下无碱速凝剂易结晶沉淀和促凝效果差的技术难题,研发出一种适用于高原寒冷地区的双组份无碱速凝剂,并提出相应的使用方法。该产品的使用将为我国西部高原寒冷地区隧道喷射混凝土用无碱速凝剂提供技术方案。(The invention belongs to the technical field of concrete admixtures, and particularly relates to a two-component alkali-free accelerator suitable for plateau cold regions and a using method thereof, wherein the two-component alkali-free accelerator comprises a quick-hardening component A and a set accelerating component B, and the mass ratio of the quick-hardening component A to the set accelerating component B is 70-80: 20-30. Wherein the rapid hardening component A is powder material mainly composed of tricalcium aluminate (C) 3 A) Calcium Hydroxide (CH), hemihydrate gypsum (CaSO) 4 ﹒0.5H 2 O) composition; the coagulation accelerator component B is a liquid material and mainly comprises polyaluminium sulfate (PAS), Triethanolamine (TEOA) and lithium sulfate (Li) 2 SO 4 ) Lactic acid (HL) and water. The invention solves the technical problems that the alkali-free accelerator is easy to crystallize and precipitate and has poor accelerating effect in the plateau low-temperature environment through the synergistic effect of the quick-hardening component and the accelerating component, develops the double-component alkali-free accelerator suitable for plateau cold regions, and provides a corresponding using method. TheThe use of the product provides a technical scheme for the alkali-free accelerator for the tunnel sprayed concrete in cold areas on western plateaus in China.)

1. The two-component alkali-free accelerator suitable for plateau cold regions and the using method are characterized by comprising a quick-hardening component A and a coagulation accelerating component B, wherein the mass ratio of the component A to the component B is 70-80: 20-30.

2. The two-component alkali-free accelerator suitable for the plateau cold regions and the use method of the two-component alkali-free accelerator as claimed in claim 1, wherein the quick-hardening component A is a powder material mainly composed of tricalcium aluminate (C)₃A) Calcium Hydroxide (CH), hemihydrate gypsum (CaSO)₄﹒0.5H₂O), and the mass ratio of the three materials is 50-80: 10-20: 10 to 30.

3. The two-component alkali-free accelerator suitable for the plateau cold regions and the using method thereof as claimed in claim 1, wherein the set accelerating component B is a liquid material, mainly composed of polyaluminium sulfate (PAS), Triethanolamine (TEOA), lithium sulfate (Li)₂SO₄) The composite material comprises lactic acid (HL) and water, wherein the mass ratio of the five materials is 20-40: 5-10: 5-10: 3-5: 35-67 parts.

4. The two-component alkali-free accelerator suitable for the plateau cold regions and the use method of the two-component alkali-free accelerator are characterized in that the quick-hardening component A is prepared in a physical mixing mode, and the preparation process of the accelerating component B comprises the following steps:

step 1: mixing polyaluminium sulfate, lithium sulfate and water, reacting for 2 hours at the temperature of 60-80 ℃, and stirring at the rotating speed of 300-500 rpm;

step 2: slowly dripping triethanolamine into the solution at a dripping speed of 1.0-1.5 ml/min, reacting for 1h at the temperature of 60-80 ℃, and stirring at the rotating speed of 300-500 rpm;

and step 3: slowly dripping lactic acid into the solution at the dripping speed of 1.5-2.0 ml/min, and adjusting the pH value of the solution to 3.0-4.0, thereby preparing the alkali-free accelerator accelerating component B.

5. The two-component alkali-free accelerator suitable for the plateau cold regions and the use method of the two-component alkali-free accelerator are characterized in that the component A and the component B in the two-component alkali-free accelerator are used simultaneously in the concrete spraying construction process, and the use steps are as follows:

step 1: after the sprayed concrete mixture is conveyed to a construction site through a tank truck, adding a powder component A with specified mass into the concrete tank truck, keeping the rotating speed of a concrete tank at 10-15 revolutions per minute, and stirring for 5 minutes;

step 2: the wet shotcrete construction is carried out immediately after the stirring is finished, and a liquid component B with specified mass is added at a nozzle, and the material is atomized by compressed air and then is fully mixed with the shotcrete in a mixing cavity.

6. The two-component alkali-free accelerator suitable for the plateau cold regions and the using method of the two-component alkali-free accelerator are characterized in that the using amount of the two-component alkali-free accelerator is 10-15% of the total mass of a cementing material in sprayed concrete.

Technical Field

The invention belongs to the technical field of concrete admixtures, and particularly relates to a double-component alkali-free accelerator suitable for plateau cold regions and a using method thereof.

Background

The accelerator is a chemical additive which can make concrete lose fluidity rapidly, and is one of the additives which must be used in the process of spraying concrete. The quick-setting admixture can be divided into an alkali quick-setting admixture and an alkali-free quick-setting admixture according to different alkali contents. After the alkali accelerating agent is used, the influence on the later strength guarantee rate of the sprayed concrete and the construction environment is large, so that the product is gradually eliminated and replaced by the alkali-free accelerating agent with more excellent product performance. The alkali-free accelerator has the advantages of small influence on later strength of sprayed concrete, small environmental pollution and the like, and is the main development direction of the accelerator for the sprayed concrete. However, in order to achieve a better accelerating effect, inorganic salt compounds having accelerating action, such as aluminum sulfate, magnesium sulfate, lithium sulfate and the like, are generally added to the alkali-free accelerator in a higher proportion. Therefore, the solid content of the alkali-free accelerator is usually high and can reach 55-65%. The outstanding problems of poor stability, unstable performance and the like of the commercially available alkali-free accelerator are caused, and particularly, when the environmental temperature changes violently, the alkali-free accelerator is more serious in a precipitation site. However, with the continuous advance of infrastructure construction in China, the emphasis of railway engineering construction has gradually shifted to the western regions in China. Taking the Yaan-Linzhi section of the Sichuan-Tibet railway to be fully built for work, the occupation ratio of the tunnel of the line is up to 82%, and the total length of the newly built tunnel is about 800 kilometers. Wherein, the alkali-free accelerator is required to be used in the construction of the primary support shotcrete of the tunnel by about 80 ten thousand tons. Therefore, the demand of infrastructure construction in western regions of China on accelerator products is huge. However, compared with the east coastal areas, the west areas of China have fluctuating topography, numerous mountains and cold climate, and the day and night temperature difference of part of the areas can reach more than 30 ℃. The natural condition of plateau cold aggravates the possibility of the crystallization and precipitation of the traditional liquid alkali-free accelerator. In western regions of China, a plurality of projects have the phenomena of crystallization, precipitation and the like of the alkali-free accelerator, and the process seriously influences the construction efficiency and the service performance of the sprayed concrete. The condensation effect of the sprayed concrete is also poor when the high-altitude low-temperature environment induces the liquid alkali-free accelerator to precipitate or even lose efficacy. Because the hydration rate of the cement particles is closely related to the ambient temperature, the low-temperature condition of the concrete mixture in the plateau low-temperature environment can obviously reduce the reaction rate of the cement particles and the accelerating agent, thereby influencing the setting and hardening effect and obviously improving the rebound rate of the sprayed concrete construction. In western areas of China, the rebound rate of sprayed concrete of partial tunnel engineering can reach more than 50%. Therefore, related researches are carried out aiming at the technical problems that the liquid alkali-free accelerator is easy to precipitate and the sprayed concrete is slow to set and harden under the high-altitude low-temperature condition, and the proposed alkali-free accelerator solution suitable for the high-altitude low-temperature condition has important significance for improving the construction performance of the sprayed concrete in western areas of China.

At present, researchers at home and abroad make certain progress in the aspects of research and development and performance improvement of alkali-free setting accelerators, but research on the technical improvement of the stability and the setting hardening performance of the setting accelerators in plateau cold environments is still relatively less. Chinese patent CN110615638A 'A low temperature resistant liquid alkali-free quick-setting admixture and a preparation method thereof' introduces a stabilizer and a reinforcing agent into the alkali-free quick-setting admixture to improve the frost resistance of the alkali-free quick-setting admixture under low temperature conditions. However, the solid content of the accelerator product reaches 55-60%, and the accelerator product is still prepared by a hydrothermal synthesis method in the production processThe solid material is dissolved in the liquid phase, and the solid material is not crystallized and separated out when the accelerator is recovered to normal temperature by using materials such as a stabilizer, so that the stability of the accelerator is ensured. However, the solubility of compounds such as aluminum sulfate gradually decreases with decreasing solution temperature, and solid phase crystallization occurs. The use of the stabilizer can only delay the process to a certain extent, but cannot fundamentally solve the problem of crystallization and precipitation of the accelerator under the low-temperature condition. Chinese patent CN107298540A 'an antifreezing alkali-free accelerator and a preparation method thereof', the technology ensures the stability of the accelerator under low temperature conditions by using an antifreezing agent. The antifreezing agent mainly comprises soluble starch, and the gelatinized components are adsorbed on the surfaces of cement particles, so that the later hydration process of the cement particles in concrete is seriously influenced. From the above analysis, the essential reason that the alkali-free accelerator is prone to stability problems in cold plateau areas is that the solid content of the commercially available alkali-free accelerator product is generally high. The water in the accelerator freezes under low temperature environment, so that the water content is reduced and the solubility of the inorganic salt is gradually reduced, and the factors jointly cause the precipitation acceleration of the alkali-free accelerator under the low temperature environment. On the other hand, the hydration rate of cement particles in a plateau low-temperature environment becomes slow, resulting in deterioration of the quick setting effect. The analysis shows that the effective component Al in the alkali-free accelerator³⁺And SO₄ ^2-After the concrete is added, the cement is mainly mixed with tricalcium aluminate (C) in the cement₃A) Calcium Hydroxide (CH), etc. However, the reaction rate of ordinary portland cement is significantly slow when the cement is superimposed on a low-temperature environment, because the tricalcium aluminate content is relatively low. According to the basic principle of chemical reaction kinetics, if the relative concentration of reactants can be improved, the reaction of the alkali-free setting accelerator and cement particles is obviously promoted, so that the setting accelerating effect is improved. Therefore, in order to improve the comprehensive performance of the alkali-free accelerator under the cold condition of the plateau and fundamentally solve the outstanding problems of easy crystallization precipitation and slow setting and hardening of the alkali-free accelerator under the low-temperature condition, the invention solves the problems by regulating and controlling the effective solid content of the alkali-free accelerator and improving the content of active minerals in concrete.

Disclosure of Invention

The invention aims to solve the problems that the traditional alkali-free accelerator is easy to crystallize and precipitate in plateau cold regions and the coagulation effect of sprayed concrete is poor at low temperature, and further provides a two-component alkali-free accelerator suitable for the plateau cold regions and a using method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

the problems that the alkali-free accelerator is easy to crystallize and precipitate and the concrete is slow to set and harden under the cold condition of the plateau are solved by reasonably controlling the effective solid content of the alkali-free accelerator and improving the content of active minerals in the sprayed concrete, so that the two-component alkali-free accelerator suitable for the cold region of the plateau is prepared, and a corresponding using method is provided. The alkali-free accelerator consists of a component A and a component B, wherein the component A is a quick-hardening component and has the function of improving the content of active minerals in sprayed concrete; the component B is a coagulation promoting component, and has the functions of ensuring the coagulation hardening effect in the concrete spraying construction process and ensuring the stability under the low-temperature condition. The component A is a powder material and is added after the concrete is transported to a working surface; the component B is a liquid material and is added at a nozzle in the construction process of spraying concrete. The two components have synergistic effect, and can effectively ensure the stability of the alkali-free accelerator and the concrete workability in cold areas on plateaus.

Specifically, the two-component alkali-free accelerator suitable for plateau cold regions and the use method thereof comprise the following components:

the quick hardening component A is a powder material (the mass percentage is 70-80 percent) and mainly comprises tricalcium aluminate (C)₃A) Calcium Hydroxide (CH), hemihydrate gypsum (CaSO)₄﹒0.5H₂O), and the mass ratio of the three materials is 60-70: 10-20: 10 to 30.

The coagulation accelerator component B is a liquid material (the mass ratio is 20-30%), and mainly comprises polyaluminium sulfate (PAS), Triethanolamine (TEOA) and lithium sulfate (Li)₂SO₄) The composite material comprises lactic acid (HL) and water, wherein the mass ratio of the five materials is 40-50: 5-10: 5-10: 3-5: 25 to 47.

The invention relates to a double-component alkali-free accelerator suitable for plateau cold regions and a use method thereof, wherein a quick-hardening component A is prepared in a physical mixing mode, and a preparation process of a coagulation accelerating component B comprises the following steps:

step 1: mixing polyaluminium sulfate, lithium sulfate and water, and reacting for 2 hours at the temperature of 60-80 ℃, wherein the stirring speed is 300-500 rpm.

Step 2: and slowly dripping triethanolamine into the solution at the dripping speed of 1.0-1.5 ml/min. Reacting for 1h at the temperature of 60-80 ℃, wherein the stirring speed is 300-500 rpm.

And step 3: slowly dripping lactic acid into the solution at a dripping speed of 1.5-2.0 ml/min, and adjusting the pH value of the solution to 3.0-4.0. Thus, the alkali-free accelerator component B was obtained.

In the two-component alkali-free accelerator suitable for the plateau cold region and the use method thereof, the component A and the component B in the two-component alkali-free accelerator are required to be used simultaneously in the concrete spraying construction process, and the use steps are as follows:

step 1: after the sprayed concrete mixture is conveyed to a construction site through a tank truck, adding a powder component A with specified mass into the concrete tank truck, keeping the rotating speed of the concrete tank at 10-15 revolutions per minute, and stirring for 5 minutes.

Step 2: the wet shotcrete construction is carried out immediately after the stirring is finished, and a liquid component B with specified mass is added at a nozzle, and the material is atomized by compressed air and then is fully mixed with the shotcrete in a mixing cavity.

The invention discloses a two-component alkali-free accelerator suitable for plateau cold regions and a using method thereof, and is characterized in that the using amount of the two-component alkali-free accelerator is 10-15% of the total mass of a cementing material in sprayed concrete.

Detailed Description

To better illustrate the features of the present invention, the following description will be given with reference to specific examples, but the present invention is not limited to the examples.

Example 1

A two-component alkali-free accelerator suitable for plateau cold regions and a preparation method of an alkali-free accelerator AB component in a using method thereof comprise the following steps:

preparation of component A

(1) 50g of tricalcium aluminate (C) are mixed by a powder mixer₃A) 20g of Calcium Hydroxide (CH) and 30g of hemihydrate gypsum (CaSO)₄﹒0.5H₂O) are evenly mixed to obtain the component A of the alkali-free setting accelerator.

Preparation of component B

(1) 67g of water, 20g of aluminum sulfate (PAS) and 5g of lithium sulfate (Li) were added at 70 deg.C₂SO₄) The mixture was mixed homogeneously, the reaction time was 2h and the stirring speed was 400 rpm.

(2) 5g of triethanolamine was slowly added dropwise to the above solution at a rate of 1.0 ml/min. The reaction was carried out at 70 ℃ for 1h with a stirring speed of 400 rpm.

(3) 3g of lactic acid was slowly dropped into the above solution at a dropping rate of 2.0 ml/min, thereby obtaining an alkali-free accelerator accelerating component B.

Example 2

A two-component alkali-free accelerator suitable for plateau cold regions and a preparation method of an alkali-free accelerator AB component in a using method thereof comprise the following steps:

preparation of component A

(1) 60g of tricalcium aluminate (C) are mixed by a powder mixer₃A) 20g of Calcium Hydroxide (CH) and 20g of hemihydrate gypsum (CaSO)₄﹒0.5H₂O) are evenly mixed to obtain the component A of the alkali-free setting accelerator.

Preparation of component B

(1) 62g of water, 25g of aluminum sulfate (PAS) and 5g of lithium sulfate (Li) at 70 DEG C₂SO₄) The mixture was mixed homogeneously, the reaction time was 2h and the stirring speed was 400 rpm.

(2) 5g of triethanolamine was slowly added dropwise to the above solution at a rate of 1.0 ml/min. The reaction was carried out at 70 ℃ for 1h with a stirring speed of 400 rpm.

(3) 3g of lactic acid was slowly dropped into the above solution at a dropping rate of 2.0 ml/min, thereby obtaining an alkali-free accelerator accelerating component B.

Example 3

A two-component alkali-free accelerator suitable for plateau cold regions and a preparation method of an alkali-free accelerator AB component in a using method thereof comprise the following steps:

preparation of component A

(1) 70g of tricalcium aluminate (C) are mixed by a powder mixer₃A) 10g of Calcium Hydroxide (CH) and 20g of hemihydrate gypsum (CaSO)₄﹒0.5H₂O) are evenly mixed to obtain the component A of the alkali-free setting accelerator.

Preparation of component B

(1) 57g of water, 30g of aluminum sulfate (PAS) and 5g of lithium sulfate (Li) were mixed at 70 ℃₂SO₄) The mixture was mixed homogeneously, the reaction time was 2h and the stirring speed was 400 rpm.

(2) 5g of triethanolamine was slowly added dropwise to the above solution at a rate of 1.0 ml/min. The reaction was carried out at 70 ℃ for 1h with a stirring speed of 400 rpm.

(3) 3g of lactic acid was slowly dropped into the above solution at a dropping rate of 2.0 ml/min, thereby obtaining an alkali-free accelerator accelerating component B.

Example 4

A two-component alkali-free accelerator suitable for plateau cold regions and a preparation method of an alkali-free accelerator AB component in a using method thereof comprise the following steps:

preparation of component A

(1) 80g of tricalcium aluminate (C) are mixed by a powder mixer₃A) 10g of Calcium Hydroxide (CH) and 10g of hemihydrate gypsum (CaSO)₄﹒0.5H₂O) are evenly mixed to obtain the component A of the alkali-free setting accelerator.

Preparation of component B

(1) 52g of water, 30g of polyaluminium sulfate (PAS) and 10g of lithium sulfate (Li) were mixed at 70 deg.C₂SO₄) The mixture was mixed homogeneously, the reaction time was 2h and the stirring speed was 400 rpm.

(2) 5g of triethanolamine was slowly added dropwise to the above solution at a rate of 1.0 ml/min. The reaction was carried out at 70 ℃ for 1h with a stirring speed of 400 rpm.

(3) 3g of lactic acid was slowly dropped into the above solution at a dropping rate of 2.0 ml/min, thereby obtaining an alkali-free accelerator accelerating component B.

The alkali-free accelerator A component and the alkali-free accelerator B component prepared in the embodiments 1 to 4 are prepared according to the mass ratio of 70:30, and are added according to the using steps of the two-component alkali-free accelerator in the construction process of sprayed concrete. In order to comparatively illustrate the stability and the coagulation accelerating effect of the two-component alkali-free accelerator under the cold condition on the plateau, a traditional alkali-free accelerator (comparative example 1) and an anti-freezing alkali-free accelerator (comparative example 2) are specially selected for carrying out a comparative test.

Comparative example 1

The traditional alkali-free setting accelerator is selected, and the preparation method comprises the steps of mixing 55g of aluminum sulfate and 35g of water, and stirring for 0.5h at the temperature of 80 ℃ and the rotating speed of 400 rpm. 7g of organic alcohol amine and 3g of inorganic acid are slowly dropped into the solution, and the dropping speed is 1.0 ml/min. The reaction was carried out at 80 ℃ for 0.5h with a stirring speed of 400 rpm.

Comparative example 2

The accelerator of comparative example 2 was prepared according to the formulation of example 5 in "an antifreeze alkali-free accelerator and its preparation method" of chinese patent CN 107298540A.

The performances of the two-component alkali-free setting accelerator prepared in the embodiments 1-4 and the performances of the traditional alkali-free setting accelerator and the frost-resistant alkali-free setting accelerator prepared in the comparative examples 1-2 are tested, the stability and the setting accelerating effect of the alkali-free setting accelerator subjected to a low-temperature environment are evaluated, and the results are shown in table 1.

Low temperature stability test method: 100ml of the liquid alkali-free accelerator is taken and placed in a measuring cylinder with a plug, the measuring cylinder is placed in an environment with the temperature of minus 20 ℃ for freezing for 20 days, and the measuring cylinder is taken out and placed in an environment with the normal temperature (20 ℃) until the ice is completely melted. The volume of the bottom precipitate/supernatant in the measuring cylinder after the alkali-free setting accelerator completely melted is recorded, so as to measure the stability of the alkali-free setting accelerator under the low-temperature condition.

The accelerating effect evaluation method comprises the following steps: in order to evaluate the coagulation accelerating effect of the alkali-free accelerator after being frozen, the alkali-free accelerator subjected to the freeze-thaw process is taken for coagulation time. And the construction resilience rate under a low-temperature environment is researched through a field test, all raw materials of the concrete are subjected to freezing treatment in the test process, and the leaving temperature of the sprayed concrete mixture is controlled to be 5 ℃.

The setting time test is obtained according to the test of accelerator for sprayed concrete (GB/T35159 and 2017), and the used liquid accelerators are all the accelerators thawed by the process. When the setting time of the two-component alkali-free accelerator is tested, the powder component A is proportionally added into the powder cementing material to be mixed.

Table 1 results of performance test of examples and comparative examples

As can be seen from Table 1: examples 1 to 4 the two-component alkali-free setting accelerator component A tricalcium aluminate (C)₃A) The content is gradually increased, and the content of polyaluminium sulfate (PAS) in the component B is gradually increased. From the low-temperature stability test results, it is known that the two-component alkali-free quick-setting agent hardly precipitates at low temperatures, as compared with the ordinary alkali-free quick-setting agent of comparative example 1 and the freeze-resistant alkali-free quick-setting agent of comparative example 2. The reason is that the effective solid content of the liquid B component in the two-component alkali-free accelerator is about 25-40%, the inorganic salt is less crystallized and precipitated after the two-component alkali-free accelerator is subjected to low-temperature conditions, and the B component of the alkali-free accelerator hardly has crystallization and precipitation under the action of the stabilizer. However, since the solid content of the common alkali-free accelerator and the anti-freezing alkali-free accelerator is about 60%, the crystallization phenomenon is easy to occur in an extremely low temperature environment (20 ℃ below zero). From the aspect of accelerating effect, the two-component alkali-free accelerator adds tricalcium aluminate (C) into the sprayed concrete mixture₃A) And the coagulation accelerating component, so that the components react rapidly and coagulate and harden after the liquid accelerator B component is added. Compared with comparative examples 1 and 2, the setting time of the two-component alkali-free setting accelerator is remarkably shortened, and the rebound rate of the arch crown and the arch waist is remarkably reduced. According to the test results, the invention solves the technical problems that the traditional alkali-free accelerator is easy to crystallize and precipitate and has poor accelerating effect in the cold environment of the plateau through researching and developing the double-component alkali-free accelerator, and effectively improves the construction quality and the construction efficiency of the sprayed concrete in the cold region of the plateau.