CN116217191B - Cold region desert sand composite alkali-activated anti-freezing mortar and preparation and construction methods thereof - Google Patents

Abstract

The desert sand composite alkali-activated anti-freezing mortar for cold areas and the preparation and construction methods thereof comprise the following components in parts by weight: 100 parts of fly ash, 20-30 parts of quicklime, 10-15 parts of alkali-activated agent, 500-800 parts of desert sand, 4-8 parts of composite water reducer and 35-50 parts of water; taking water with the temperature of 60-80 ℃ and an alkali excitant according to the mixing proportion, fully stirring and mixing, and placing the mixture in a curing box with the temperature of 60-80 ℃ for standby after fully dissolving; weighing fly ash, quicklime and desert sand according to the mixing ratio, mixing and stirring uniformly, and slowly adding the prepared alkali-exciting agent solution and stirring uniformly; filling the prepared mixed mortar into cracks and holes, trowelling and cleaning the filling surface after filling, covering a plastic film and curing; the scheme of the invention is simple, green and environment-friendly, and the cost is low; the grouting slurry has high fluidity, good filling property, early strength and quick hardening of slurry molding, and durable hardening material, and can be widely applied to practical engineering such as filling holes, foundation pits and cracks in northern cold areas.

Description

Cold region desert sand composite alkali activated antifreeze mortar and its preparation and construction method

Technical Field

The invention relates to the technical field of antifreeze of cold region construction projects, and in particular to a cold region desert sand composite alkali-activated antifreeze mortar and a preparation and construction method thereof.

Background Art

With the development of cold region economy, the demand for mortar for engineering construction is increasing. Cold region buildings such as highway pavement, bridge piers, high-voltage iron tower pile foundations, etc. are susceptible to freeze-thaw damage and cracks; hot rod foundation pits need high fluidity, uniformity, and rapid backfilling of foundation pit gaps during backfilling. In addition, desert sand is widely distributed in cold regions. At present, there are no related reports on alkali-activated mortar technology developed for cold region projects.

Patent application CN202011347104.1 discloses a slag-based alkali-activated cementitious material, a preparation method and an application thereof. The components of the alkali-activated cementitious material are: 70-99 parts by mass of slag, 1-30 parts by mass of calcium-silicon slag, 1%-5% of alkali activator, and the alkali-activated liquid is sodium silicate with a modulus of 2.2-3.4. Patent application CN201510810774.5 discloses a modified alkali-activated cementitious material. The raw materials include, by mass, 100 parts of fly ash and slag, 25-50 parts of alkali activator, 0.5-2 parts of retarder, and 2-15 parts of polymer rubber powder, wherein the solid content of the alkali activator is 30%-40%, and the polymer rubber powder is selected from one or more of butadiene-styrene copolymer rubber powder, styrene-acrylic acid copolymer rubber powder, acrylate copolymer rubber powder, ethylene vinyl acetate copolymer rubber powder, vinyl acetate-versatate vinyl ester copolymer rubber powder, or vinyl acetate-versatate vinyl ester-acrylate copolymer rubber powder.

The above-mentioned existing alkali-activated cementitious materials have the following defects: (1) Most alkali-activated mortars are designed from the perspective of materials science and have no engineering specificity, especially there is no alkali-activated mortar suitable for cold-region projects; (2) Alkali activation mostly adopts a composite alkali activation combination of NaOH and _Na2SiO4 , and the activation effect still has a lot of room for improvement; (3) The powder uses fly ash and _slag , which does not achieve efficient alkali activation of fly ash, and the strength of the generated mortar is relatively low; (4) The fluidity of the mortar is rarely considered. However, in cold-region filling projects, the fluidity directly determines the filling density and later durability.

Summary of the invention

In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a cold-region desert sand composite alkali-activated antifreeze mortar and a preparation and construction method thereof. Common desert sand and fly ash in cold regions are used as raw materials, and composite alkali activation technology and durability improvement measures are adopted to prepare mortar suitable for cold-region engineering construction. The mortar can solve the current technical problems in cold-region engineering, has the advantages of local materials, convenient construction, early strength and fast hardening, good antifreeze performance, and good filling performance, and makes full use of local resources to reduce engineering costs.

In order to achieve the above object, the technical solution adopted by the present invention is:

A cold region desert sand composite alkali-activated antifreeze mortar comprises the following components by weight: 100 parts of fly ash, 20-30 parts of quicklime, 10-15 parts of alkali activator, 500-800 parts of desert sand, 4-8 parts of composite water reducing agent, and 35-50 parts of water.

The fly ash comprises active SiO ₂ , active Al ₂ O ₃ and f-CaO in any proportion accounting for 50%-70% of the fly ash mass, and Fe ₂ O ₃ accounting for 5%-10% of the fly ash mass. The fly ash fineness is less than 100um.

The quicklime is common ground quicklime, in which CaO accounts for more than 70% of the quicklime mass, and the quicklime is medium-speed lime.

The alkaline activator is a composite activator, comprising uniformly mixed NaOH accounting for 1%-2% of the mass of the alkaline activator and CaCl ₂ accounting for 2%-3% of the mass of the alkaline activator.

The desert sand has a particle size of 25um-400um and a fineness modulus of 0.2-0.3.

The composite water reducing agent is an air entraining type water reducing agent, with a water reduction rate greater than 25% and an air entraining amount of 6%-15%.

The temperature of the water is between 60°C and 80°C.

A method for preparing cold region desert sand composite alkali activated antifreeze mortar comprises the following steps:

(1) Take water at 60°C to 80°C and an alkali activator according to the antifreeze mortar mix ratio of claim 1, stir and mix thoroughly, and place in a 60°C to 80°C curing box for standby after being fully dissolved;

(2) According to the antifreeze mortar mix ratio of claim 1, fly ash, quicklime and desert sand are weighed, mixed and stirred evenly, and then the alkaline activator solution prepared in step (1) is slowly added;

(3) The mortar obtained in step (2) is stirred at a speed of 100-150 r/min for 5-8 min, and the composite water reducing agent and water are slowly added during the stirring process.

The amount of water used in step (3) = the total amount of water used - the amount of water used in the alkali excitation.

A construction method of cold region desert sand composite alkali activated antifreeze mortar, specifically comprising the following steps:

Step 1: Prepare water, electricity, pipes and other construction materials, level the ground of the rock cracks and holes, and then inject running water into the cracks and holes to flush them clean;

Step 2: pouring the mortar mixed in the step (3) of preparing the desert sand-alkali activated antifreeze mortar, the construction is continuous to avoid segregation and leakage, and ensure that the pouring is completed before the mortar begins to set;

Step 3: After filling the gaps and holes, smooth and clean the poured surface and cover it with plastic film for maintenance.

The beneficial effects of the present invention are:

(1) Desert sand, which is widely distributed in the north, is used as the main raw material. It is easy to obtain, low-priced, green and environmentally friendly, and has good engineering applicability. It has significant advantages in terms of economy and environmental protection. The particle size composition of desert sand is shown in Table 1. The average particle size of desert sand is 0.04mm-0.08mm. Due to its small particle size, the mortar prepared with it has an inherent advantage of good fluidity; the characteristics of desert sand particles are shown in Table 2 and Figure 1. Its surface is relatively rough, and its bonding strength when preparing mortar is close to that of standard sand; the chemical composition of desert sand is shown in Table 3. Its alkaline components such as CaO, _K2O and _Na2O are higher than those of ordinary sand, especially the CaO content is close to 17%. The alkaline components mainly composed of CaO in desert sand can supplement the deficiency of alkaline raw materials in alkali-activated materials, increase the gelling effect of alkali activation, and are conducive to the generation of alkali-activated strength.

Table 1 Grain size composition of desert sand on the Qinghai-Tibet Plateau (W%)

Table 2 Characteristics of desert sand

Table 3 Chemical composition of desert sand

(2) Use the optimal ratio of fly ash and quicklime. Fly ash belongs to the Cao-SiO ₂ -Al ₂ O ₃ system, and its composition is shown in Table 4. Compared with ordinary Portland cement clinker, fly ash has a lower CaO content and is "congenitally calcium deficient". Therefore, supplementing the CaO content and increasing the amount of Ca(OH) ₂ generated are more conducive to the hydration and hardening of fly ash to form strength. The CaO content in quicklime is 70%-76%, and the cost is low, making it very suitable as an auxiliary material for fly ash. Through a large number of experiments, it was found that the best mechanical properties can be obtained when the ratio of fly ash to lime is 75:25. The heat generated by quicklime during digestion (up to 80℃-90℃) and the consumption of water can promote the activation of fly ash activity and reduce the porosity of the hardening system. The temporary high concentration of OH ^-1 in the system corrodes the surface of fly ash particles, destroying its ≡Si-O-Si≡ and Si-O-Al≡ grid structure, thereby achieving a better activation effect.

Table 4 Chemical composition of fly ash

(3) The composite alkali activator of NaOH and _CaCl2 is used, which has a good strength activating effect. The components of fly ash are acidic oxides, so it has a certain weak acidity. The ^OH- in NaOH can break and cleave the Si-O bonds and Al-O bonds in the fly ash, thereby enhancing the activity of the fly ash; at the same time, the Na ⁺ in NaOH can change the fly ash glass network structure, disintegrate the network structure, and improve the activity of the fly ash. The Ca2 ⁺ and ^Cl- in _CaCl2 can diffuse well into the fly ash particles, react chemically with _the active _Al2O3 in the fly ash, generate CAH, increase the internal and external osmotic pressure, and destroy the fly ash inclusions; _CaCl2 can also react chemically with Ca(OH) ₂ in the system to generate calcium oxychloride complex salt, which is insoluble in water, and increases the solid phase component in the system, thereby increasing the strength of the system (Figure 2).

(4) Use composite water reducer to increase strength and durability. Composite water reducer is a high-efficiency air-entraining water reducer that has a dispersing effect on powder particles, can improve its workability, reduce unit water consumption, improve fluidity, and save powder materials. The addition amount is 1.5%-2.5% of the total mass of the silt. While keeping the slump unchanged, the mixing water consumption is reduced by 10%-20%; or while keeping the water-cement ratio unchanged, the fluidity of the mortar is increased by 25%-35%. At the same time, the composite water reducer can introduce a large number of tiny, closed and evenly distributed bubbles during the mixing process to reduce the bleeding and segregation of the mixture, improve workability, and significantly improve the frost resistance and durability of the mortar. The composite water reducer can make the mortar have high strength and high durability at the same time. After testing, the basic properties are shown in Table 5.

Table 5 Basic parameters of mortar durability

In summary, the present invention uses common desert sand and fly ash in cold regions as raw materials, adopts alkali activation technology and durability improvement measures to prepare mortar suitable for cold region engineering construction, which can solve the current technical problems of cold region engineering; the technical solution is simple, resource-rich, green and environmentally friendly, and low-cost; the pouring slurry has high fluidity and good filling properties, the slurry is formed early and hardens quickly, and has the advantage of durable hardened materials, and can be widely used in the filling construction of holes, foundation pits, and cracks in northern cold regions.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a characteristic diagram of different types of sand under an electron microscope magnified 1000 times, where (a) is standard sand, (b) is Qinghai-Tibet Plateau desert sand, and (c) is Maowusu Desert sand.

FIG. 2 is a graph showing the composite stimulator strength results of the present invention.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Example 1

A cold region desert sand composite alkali activated antifreeze mortar, mainly used in northern cold region engineering construction, including the following components:

100 parts of fly ash, 20 parts of quicklime, 10 parts of alkali activator, 500 parts of desert sand, 4 parts of composite water reducer, and 35 parts of water; the fly ash is industrial fly ash, such as solid waste discharged from coal-fired power plants, and any proportion of active _SiO2 , active _Al2O3 and f-CaO (free calcium oxide) accounts for 50% of the fly ash mass, _{and Fe2O3} accounts for 5% of the fly _ash mass; the alkali activator is a composite activator, containing evenly mixed NaOH accounting for 1% of the mass of the alkali activator and _CaCl2 accounting for 2% of the mass of the alkali activator; the composite water reducer is an air-entraining type water reducer with a water reduction rate of 25% and an air entrainment amount of 6%; the water temperature is 60°C.

A method for preparing cold region desert sand composite alkali activated antifreeze mortar comprises the following steps:

(1) Prepare the composite alkali activator: Take 10 parts of NaOH accounting for 1% of the mass of the alkali activator and CaCl ₂ accounting for 2% of the mass of the alkali activator, mix them thoroughly with 60°C water to dissolve, and place them in a 60°C curing box for use after they are fully dissolved;

(2) Take 100 parts of fly ash, 20 parts of quicklime and 500 parts of desert sand, stir repeatedly until evenly mixed and set aside;

(3) slowly adding the composite activator solution prepared in step (1) into the mortar obtained in step (2), stirring in a stirrer at a speed of 120 r/min, and slowly adding 4 parts of air-entraining water-reducing agent and water during stirring, wherein the amount of water used = the total amount of water used - the amount of water used in alkali activation;

Due to the effect of the water reducer, the mortar will become viscous, so the entire water adding and stirring time is 8 minutes. The desert sand alkali activated antifreeze mortar material is sealed and stored for later use. The mortar engineering parameters are shown in Table 6.

A construction method of cold region desert sand composite alkali activated antifreeze mortar, comprising the following steps:

Step 1: Prepare water, electricity, pipelines and other construction materials, level the ground of the rock crack, and then inject running water into the crack to clean it, thereby increasing the bonding force between the rock and the cementitious material;

Step 2: Pour the prepared desert sand-alkali activated antifreeze mortar into the mortar. It should be noted that continuous construction is required to avoid segregation and leakage, and the pouring is completed before the mortar begins to set;

Step 3. After the filling is completed, the poured surface is smoothed and cleaned, and covered with plastic film to prevent moisture loss and surface drying and cracking during the curing process, thereby improving the mortar strength.

Table 6 Mortar engineering parameters

Example 2

A cold region desert sand composite alkali activated antifreeze mortar, mainly used in northern cold region engineering construction, including the following components:

100 parts of fly ash, 25 parts of quicklime, 13 parts of alkali activator, 600 parts of desert sand, 6 parts of composite water reducer, and 40 parts of water; the fly ash is industrial fly ash, such as solid waste discharged from coal-fired power plants, and any proportion of active _SiO2 , active _Al2O3 and f-CaO (free calcium oxide) accounts for 51.3% of the fly ash mass, and _Fe2O3 accounts for 5.1% of the fly _ash mass; the alkali activator is a composite _activator , containing evenly mixed NaOH accounting for 1.5% of the mass of the alkali activator and _CaCl2 accounting for 2.3% of the mass of the alkali activator; the composite water reducer is an air-entraining type water reducer with a water reduction rate of 22.4% and an air entrainment amount of 6.5%; the temperature of the water is 70°C.

A method for preparing cold region desert sand composite alkali activated antifreeze mortar comprises the following steps:

(1) Prepare a composite alkali activator: Take 13 parts of NaOH accounting for 1.5% of the mass of the alkali activator and CaCl ₂ accounting for 2.3% of the mass of the alkali activator, mix them thoroughly with 60°C water to dissolve, and place them in a 70°C curing box for use after they are fully dissolved;

(2) Take 100 parts of fly ash, 25 parts of quicklime and 600 parts of desert sand, stir repeatedly until evenly mixed and set aside;

(3) slowly adding the composite activator solution prepared in step (1) into the mortar obtained in step (2), stirring in a stirrer at a speed of 120 r/min, and slowly adding 6 parts of air-entraining water-reducing agent and water during stirring, wherein the amount of water used = the total amount of water used - the amount of water used in alkali activation;

Due to the effect of the water reducer, the mortar will become viscous, so the entire water adding and stirring time is 8 minutes. The desert sand alkali activated antifreeze mortar material is sealed and stored for later use. The mortar engineering parameters are shown in Table 7.

A construction method of cold region desert sand composite alkali activated antifreeze mortar, comprising the following steps:

Step 1: Prepare water, electricity, pipelines and other construction materials, level the ground of the rock crack, and then inject running water into the crack to clean it, thereby increasing the bonding force between the rock and the cementitious material;

Step 2: Pour the prepared desert sand-alkali activated antifreeze mortar into the mortar. It should be noted that continuous construction is required to avoid segregation and leakage, and the pouring is completed before the mortar begins to set;

Step 3. After the filling is completed, the poured surface is smoothed and cleaned, and covered with plastic film to prevent moisture loss and surface drying and cracking during the curing process, thereby improving the mortar strength.

Table 7 Mortar engineering parameters

Example 3

A cold region desert sand composite alkali activated antifreeze mortar, comprising the following components:

100 parts of fly ash, 23 parts of quicklime, 14 parts of alkali activator, 620 parts of desert sand, 6 parts of composite water reducer, and 42 parts of water; the fly ash is industrial fly ash, such as solid waste discharged from coal-fired power plants, and any proportion of active _SiO2 , active _Al2O3 and f-CaO (free calcium oxide) accounts for 57% of the fly ash mass, _{and Fe2O3} accounts for 5.7% of the fly _ash mass; the alkali activator is a composite activator, containing uniformly mixed NaOH accounting for 1.4% of the mass of the alkali activator and _CaCl2 accounting for 2.3% of the mass of the alkali activator; the composite water reducer is an air-entraining type water reducer with a water reduction rate of 22.4% and an air entrainment amount of 6.5%; the temperature of the water is 70°C.

A method for preparing cold region desert sand composite alkali activated antifreeze mortar comprises the following steps:

(1) Prepare a composite alkali activator: Take 14 parts of NaOH accounting for 1.4% of the mass of the alkali activator and CaCl ₂ accounting for 2.3% of the mass of the alkali activator, mix them thoroughly with 70°C water to dissolve, and place them in a 70°C curing box for use after they are fully dissolved;

(2) Take 100 parts of fly ash, 23 parts of quicklime and 620 parts of desert sand, stir repeatedly until they are evenly mixed and set aside;

(3) slowly adding the composite activator solution prepared in step (1) into the mortar obtained in step (2), stirring in a stirrer at a speed of 120 r/min, and slowly adding 6 parts of air-entraining water-reducing agent and water during stirring, wherein the amount of water used = the total amount of water used - the amount of water used in alkali activation;

Due to the effect of the water reducer, the mortar will become viscous, so the entire water adding and stirring time is 8 minutes. The desert sand alkali activated antifreeze mortar material is sealed and stored for later use. The mortar engineering parameters are shown in Table 8.

A construction method of cold region desert sand composite alkali activated antifreeze mortar, comprising the following steps:

Step 1: Prepare water, electricity, pipelines and other construction materials, level the ground of the rock crack, and then inject running water into the crack to clean it, thereby increasing the bonding force between the rock and the cementitious material;

Step 2: Pour the prepared desert sand-alkali activated antifreeze mortar into the mortar. It should be noted that continuous construction is required to avoid segregation and leakage, and the pouring is completed before the mortar begins to set;

Step 3. After the filling is completed, the poured surface is smoothed and cleaned, and covered with plastic film to prevent moisture loss and surface drying and cracking during the curing process, thereby improving the mortar strength.

Table 8 Mortar engineering parameters

Example 4

A cold region desert sand composite alkali activated antifreeze mortar, comprising the following components:

100 parts of fly ash, 28 parts of quicklime, 13 parts of alkali activator, 700 parts of desert sand, 7 parts of composite water reducer, and 47 parts of water; the fly ash is industrial fly ash, such as solid waste discharged from coal-fired power plants, and any proportion of active _SiO2 , active _Al2O3 and f-CaO (free calcium oxide) accounts for 50% of the fly ash mass, _{and Fe2O3} accounts for 5% of the fly _ash mass; the alkali activator is a composite activator, containing evenly mixed NaOH accounting for 1.3% of the mass of the alkali activator and _CaCl2 accounting for 2.6% of the mass of the alkali activator; the composite water reducer is an air-entraining type water reducer with a water reduction rate of 25% and an air entrainment amount of 6%; the water temperature is 60°C.

A method for preparing cold region desert sand composite alkali activated antifreeze mortar comprises the following steps:

(1) Prepare a composite alkali activator: Take 13 parts of NaOH accounting for 1.3% of the mass of the alkali activator and CaCl ₂ accounting for 2.6% of the mass of the alkali activator, mix them thoroughly with 60°C water to dissolve, and place them in a 60°C curing box for use after they are fully dissolved;

(2) Take 100 parts of fly ash, 28 parts of quicklime and 700 parts of desert sand, stir repeatedly until evenly mixed and set aside;

(3) slowly adding the composite activator solution prepared in step (1) into the mortar obtained in step (2), stirring in a stirrer at a speed of 120 r/min, and slowly adding 7 parts of air-entraining water-reducing agent and water during stirring, wherein the amount of water used = the total amount of water used - the amount of water used in alkali activation;

Due to the effect of the water reducer, the mortar will become viscous, so the entire water adding and stirring time is 8 minutes. The desert sand alkali activated antifreeze mortar material is sealed and stored for later use. The mortar engineering parameters are shown in Table 8.

A construction method of cold region desert sand composite alkali activated antifreeze mortar, comprising the following steps:

Step 1: Prepare water, electricity, pipelines and other construction materials, level the ground of the rock crack, and then inject running water into the crack to clean it, thereby increasing the bonding force between the rock and the cementitious material;

Step 2: Pour the prepared mortar into the mortar. It should be noted that continuous construction is required to avoid segregation and leakage, and the pouring should be completed before the mortar begins to set;

Step 3. After the filling is completed, the poured surface is smoothed and cleaned, and covered with plastic film to prevent moisture loss and surface drying and cracking during the curing process, thereby improving the mortar strength.

Table 9 Mortar engineering parameters

The above-mentioned specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification, equivalent substitution and improvement of the present invention within the spirit of the present invention and the protection scope of the claims shall be included in the protection scope of the present invention.

Claims (5)

1. The desert sand composite alkali-activated anti-freezing mortar in cold areas is characterized in that: the weight portion of the mixture is as follows: 100 parts of fly ash, 20-30 parts of quicklime, 10-15 parts of alkali-activated agent, 500-800 parts of desert sand, 4-8 parts of composite water reducer and 35-50 parts of water;

the fly ash comprises active SiO ₂, active Al ₂O₃ and f-CaO which account for 50-70% of the fly ash by mass, fe ₂O₃ which accounts for 5-10% of the fly ash by mass, and the fineness of the fly ash is less than 100um;

The quicklime is common ground quicklime, caO accounts for more than 70% of the quicklime in mass, and the quicklime is middle-speed lime;

the average grain diameter of the desert sand is 0.04-0.08 mm;

the alkali excitant is a compound excitant comprising NaOH and CaCl ₂;

the composite water reducing agent is an air entraining water reducing agent;

and the cold region desert sand composite alkali-activated anti-freezing mortar is prepared by the following steps:

(1) According to the mixing proportion of the anti-freezing mortar, water at 60-80 ℃ and an alkali-exciting agent are fully stirred and mixed, and the mixture is placed in a curing box for standby after being fully dissolved;

(2) Weighing fly ash, quicklime and desert sand according to the mixing ratio of the anti-freezing mortar, uniformly mixing and stirring, and slowly adding the alkali-activated agent solution prepared in the step (1);

(3) Stirring the mortar obtained in the step (2), and slowly adding a composite water reducing agent and water in the stirring process;

water usage in step (3 = total water usage-water usage in the alkali-activator solution.

2. The desert sand composite alkali-activated anti-freezing mortar in cold areas according to claim 1, which is characterized in that: the alkali excitant is a compound excitant and comprises NaOH accounting for 1-2% of the mass of the alkali excitant and CaCl ₂ accounting for 2-3% of the mass of the alkali excitant which are uniformly mixed.

3. The desert sand composite alkali-activated anti-freezing mortar in cold areas according to claim 1, which is characterized in that: the water reducing rate of the air entraining type water reducing agent is more than 25%, and the air entraining amount is 6% -15%.

4. A preparation method of cold region desert sand composite alkali-activated anti-freezing mortar based on any one of claims 1 to 3, which is characterized by comprising the following steps: the method specifically comprises the following steps:

(1) Taking water with the temperature of 60-80 ℃ and an alkali-activated agent according to the mixing proportion of the anti-freezing mortar, fully stirring and mixing, and placing the mixture in a curing box with the temperature of 60-80 ℃ for standby after the mixture is fully dissolved;

(2) Weighing fly ash, quicklime and desert sand according to the mixing ratio of the anti-freezing mortar, uniformly mixing and stirring, and slowly adding the alkali-activated agent solution prepared in the step (1);

(3) Stirring the mortar obtained in the step (2) at a speed of 100-150r/min for 5-8min, and slowly adding the composite water reducing agent and water in the stirring process;

water usage in step (3 = total water usage-water usage in the alkali-activator solution.

5. The construction method for preparing the desert sand composite alkali-activated anti-freezing mortar in cold areas based on the method of claim 4 is characterized by comprising the following steps: the method specifically comprises the following steps:

Firstly, preparing water, electricity and pipeline construction materials, leveling the ground of rock cracks and holes, and then injecting running water into the cracks and holes to clean the inside of the cracks and holes;

secondly, pouring and filling the prepared mixed mortar, wherein the construction is continuous construction, so that segregation and slurry leakage are avoided, and pouring is completed before the mortar is initially set;

and thirdly, after filling the gaps and the holes, trowelling and cleaning the pouring surface, and covering a plastic film for maintenance.