CN109293301B

CN109293301B - Anti-freezing concrete

Info

Publication number: CN109293301B
Application number: CN201811117107.9A
Authority: CN
Inventors: 李鹏宇
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-25
Filing date: 2018-09-25
Publication date: 2021-06-01
Anticipated expiration: 2038-09-25
Also published as: CN109293301A

Abstract

The invention discloses an antifreezing concrete, which belongs to the field of building materials and comprises, by weight, 289 parts of 206-type cement, 1040 parts of 982-type gravel, 442 parts of 358-type river sand, 52-68 parts of fly ash, 75-96 parts of mineral powder, 50-75 parts of silica powder, 2.55-5.78 parts of an expanding agent, 10-20 parts of hollow glass beads, 4-7 parts of a water reducing agent, 10-20 parts of an antifreezing agent, 10-15 parts of bentonite and 226 parts of 182-type water. The high-temperature-resistant cable can adapt to temperature changes in alpine regions, is not easy to freeze, has high strength, compact structure and good durability, and is not easy to crack.

Description

Anti-freezing concrete

Technical Field

The invention relates to the field of building materials, in particular to antifreezing concrete.

Background

Concrete, referred to as concrete for short, is a general name of engineering composite materials formed by cementing aggregate into a whole by cementing materials, cement is used as the cementing material, sand and stone are used as the aggregate, and the concrete can be mixed with water, additives and the like according to a certain proportion and is obtained by stirring, and is widely applied to civil engineering.

In recent years, with the continuous and rapid development of the economy of China, the construction strength and scale of the infrastructure of China are also continuously increased, the application of concrete members is more and more, and the concrete is widely applied to the engineering fields of underground engineering, bridges, pools, tunnels, wharfs, hydropower stations and the like.

According to the regulation of construction engineering winter construction regulations (JGJ104-2011), when the outdoor average temperature is less than 5 ℃ continuously for 5 days, winter construction is started, and when the outdoor average temperature is more than 5 ℃ continuously for 5 days, the winter construction is removed. When the concrete is constructed in winter, if the maintenance measures are not proper, when the temperature of newly poured concrete is lower than 4 ℃, water in the concrete can be frozen, the frozen water can not carry out hydration reaction, and the volume of the frozen water is increased, so that the durability of the concrete is insufficient.

In China, the annual average temperature in alpine regions is low, the negative temperature time is as long as 7 months, when the temperature is low, the hydration of cement can be delayed, the concrete construction time is influenced, and due to the fact that the temperature difference change in the alpine regions is large, the concrete is prone to cracking, crisping and water seepage after being repeatedly frozen and melted for many times, indexes such as strength, toughness and stability of the concrete are seriously influenced, the durability of the structure is lost, the normal use function of the structure is even seriously influenced, and the actual service life of the engineering is shortened.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the antifreezing concrete which can adapt to the temperature change in the alpine region, is not easy to freeze, has high strength, compact structure, is not easy to crack and has good durability.

The technical purpose of the invention is realized by the following technical scheme:

an antifreezing concrete comprises, by weight, 289 parts of cement 206-.

By adopting the technical scheme, because the concrete is doped with the antifreezing agent, the freezing point of concrete mortar can be effectively reduced, the antifreezing performance of the concrete at negative temperature is improved, the concrete forms an early structure adaptive to hydration, the activation energy of water is increased, and the reaction speed of water and cement at negative temperature is accelerated, so that the antifreezing concrete disclosed by the invention can adapt to temperature change in alpine regions and can be constructed at low temperature. Meanwhile, the bentonite and the silica micropowder are added, so that the effective strength and the viscosity characteristic of the concrete are effectively improved, the mechanical property of the concrete is enhanced, and the bentonite has viscosity, so that the combination degree of the components in the concrete is enhanced, the connection between aggregates is tighter, the concrete structure is compact, and the performances of crack resistance, seepage resistance, durability and the like of the concrete are improved.

The antifreezing agent further comprises, by weight, 20-30 parts of calcium nitrite, 10-15 parts of cationic polyacrylamide, 5-8 parts of urea, 12-20 parts of sodium lignosulphonate, 1-5 parts of an initiator, 1-5 parts of micron-sized shell powder, 5-8 parts of a mesoporous molecular sieve, 5-10 parts of polyethylene glycol, 3-8 parts of pumice powder and 30-50 parts of water.

By adopting the technical scheme, because the antifreezing agent provided by the invention is a composite antifreezing agent, and the added calcium nitrite, urea and polyethylene glycol are common antifreezing agent components, the freezing point of the solution can be reduced, so that the crystal lattice structure of ice is seriously deformed and cannot form frost heaving force, the concrete can still be subjected to hydration reaction at negative temperature, the early structure of the concrete cannot be damaged, and the concrete is ensured to have higher early strength and better later strength. Meanwhile, cationic polyacrylamide and sodium lignosulfonate are added into the antifreezing agent provided by the invention, so that substances containing cations can be decomposed and can be adsorbed to the surface of clay in a limited way, the adsorption of soil and stone powder on the effective components of the antifreezing agent and additives is reduced, the hydration effect of cement is improved, in addition, the antifreezing agent can be used as a carrier of the antifreezing agent due to the microporous structures of the mesoporous molecular sieve and the pumice powder, the antifreezing agent is carried and dispersed into cement mortar, the contact area with the concrete mortar is increased, and the utilization rate of the antifreezing agent is improved. When the temperature is lower, the antifreezing agent provided by the invention can effectively reduce the freezing point of concrete, improve the hydration reaction, ensure that the concrete has higher strength during winter construction, cannot generate cracks, improve the durability of the concrete and improve the working performance of the concrete.

Further, the initiator comprises an oxidizing agent and a reducing agent in a mass ratio of 1: 0.3-1.2.

The invention further discloses that the oxidant is at least one selected from hydrogen peroxide, potassium persulfate and ammonium persulfate; the reducing agent is at least one selected from potassium sulfite, potassium thiosulfate and oxalic acid.

Further, the antifreeze is prepared by the following steps:

(1) preparing solution A from calcium nitrite, cationic polyacrylamide, urea, sodium lignosulphonate and 4/5 formula amount of water at 50-60 ℃, and preserving heat;

(2) preparing an initiator and the rest of the formula amount of water into a solution B;

(3) dropwise adding the solution B in the step (2) into the solution A in the step (1), heating to 60-65 ℃, preserving heat, reacting for 1-2h, cooling to 30-40 ℃, and adding a sodium hydroxide solution to adjust the pH value of the reaction solution to 6.5-7.5;

(4) and (4) adding polyethylene glycol, a mesoporous molecular sieve, micron-sized shell powder and pumice powder into the reaction liquid obtained in the step (3), and stirring and mixing uniformly to obtain the antifreezing agent.

By adopting the technical scheme, the antifreezing agent can be prepared by adopting the steps of the method, so that the freezing point of concrete during winter construction is effectively reduced, water icing in the hydration process of cement wool is prevented, the antifreezing concrete can adapt to construction in alpine regions, high early strength and compact structure can be ensured, and cracks are prevented.

Further, the particle size of the micron shell powder is 1-3 μm.

Further, the mineral powder is S95 blast furnace slag powder.

Through adopting above-mentioned technical scheme, owing to adopt blast furnace slag powder, improve the pore structure and the intensity after the concrete sclerosis, again because the powdered ore fineness is higher, can adsorb on cement granule surface, make the cement flocculation structure that probably forms originally can't form, play the effect of similar water-reducing agent in proper order, can show the flow velocity that improves the concrete mixture under the same circumstances of water consumption, improve its flow property, and have certain effect to the early pore structure who improves the concrete, be favorable to improving the durability of concrete.

Further, the expanding agent is azodicarbonamide plastic expanding agent.

By adopting the technical scheme, the azodicarbonamide plastic expanding agent is selected, so that the micro-expansion can be generated in the plastic stage of the anti-freezing concrete to compensate the shrinkage in the plastic stage, and the anti-freezing concrete has compact internal structure, better chlorine ion permeability resistance and better durability.

Furthermore, the content of the spherical glass bodies in the fly ash is more than 70%, the particle size of the fly ash is continuously distributed and is less than or equal to 3 mu m, and the water requirement ratio is not more than 95%.

By adopting the technical scheme, because the fly ash with smaller particle size is added and the added sand is matched as aggregate, better density of the solidified concrete can be ensured, so that the strength of the concrete can be improved to meet the use requirement, the content of spherical glass bodies in the fly ash is higher, the surfaces of the glass bodies are smooth, have no edges and corners and have stable performance, the fly ash plays a lubricating role in the concrete, the frictional resistance between concrete mixtures is reduced, the workability of the concrete mixtures can be obviously improved, the hydration heat is reduced, the drying shrinkage rate of the concrete is reduced, and the impermeability, frost resistance, elastic modulus and the like of the concrete are effectively improved.

Further, the water reducing agent is a polycarboxylic acid water reducing agent.

In conclusion, the invention has the following beneficial effects:

firstly, because the antifreezing agent is added, the freezing point of concrete mortar can be effectively reduced, the antifreezing performance of concrete at negative temperature is improved, the concrete forms an early structure adaptive to hydration, the activation energy of water is increased, and the reaction speed of water and cement at negative temperature is accelerated, so that the antifreezing concrete can adapt to the temperature change in alpine regions and can be constructed at low temperature. Meanwhile, the bentonite and the silica micropowder are added, so that the effective strength and the viscosity characteristic of the concrete are effectively improved, the combination degree of the components in the concrete is enhanced, the concrete structure is compact, and the performances of crack resistance, seepage resistance, durability and the like of the concrete are improved.

Secondly, the antifreezing agent provided by the invention is a composite antifreezing agent, cationic polyacrylamide and sodium lignosulfonate are added on the basis of adding calcium nitrite, urea and polyethylene glycol which are active ingredients of a common antifreezing agent, so that substances containing cations can be decomposed and can be adsorbed to the surface of clay in a limited way, the adsorption of soil and stone powder on the active ingredients of the antifreezing agent and additives is reduced, the hydration effect of cement is improved, in addition, the antifreezing agent can be used as a carrier of the antifreezing agent due to the microporous structures of mesoporous molecular sieves and pumice powder, the antifreezing agent is carried and dispersed in cement mortar, the contact area with the concrete mortar is increased, the utilization rate of the antifreezing agent is improved, and the cost is reduced.

Thirdly, the invention selects the azodicarbonamide plastic expanding agent, so that the micro-expansion can be generated in the plastic stage of the anti-freezing concrete to compensate the shrinkage in the plastic stage, therefore, the anti-freezing concrete has compact internal structure, better anti-chloride ion permeability and better durability.

Detailed Description

The present invention will be described in further detail with reference to examples. It should be understood that the preparation methods described in the examples are only for illustrating the present invention and are not to be construed as limiting the present invention, and that the simple modifications of the preparation methods of the present invention based on the concept of the present invention are within the scope of the present invention as claimed.

In the following examples, the materials used are all commercially available. Wherein, waterThe mud is P.O 42.5 grade Portland cement with surface area of 326m²Per Kg, the initial setting time is 150min, and the final setting time is 280 min; the river sand is natural medium sand with apparent density of 2669kg/m³The mud content is 2.4%, the water content is 2.4%, and the fineness modulus is 2.79; the crushed stone is selected from crushed stone with 5-20mm particle size and continuous gradation, and has apparent density of 2706kg/m³The crush index is 5.6%; the fly ash is II-grade fly ash, the ignition loss is 3.25 percent, the water demand is 95 percent, and the fineness is 12 percent; the water reducing agent is AN AN4000 polycarboxylic acid high-performance water reducing agent produced by Beijing, the density is 1.049g/cm3, the pH value is 5.8, the water reducing rate is 32%, the gas content is 4.0%, the solid content is 22.16%, and the degree of collapse is 10mm after 1 h; the particle sizes of the silicon micro powder and the hollow glass beads are both 200-300 meshes; the water is drinking water, wherein the pH value is 5-8, and the chloride is calculated by Cl-<1800mg/L, sulfate calculated as SO42-<2100mg/L。

Preparation example 1 of antifreeze

(1) Preparing 20kg of calcium nitrite, 10kg of cationic polyacrylamide, 5kg of urea, 12kg of sodium lignosulphonate and 24kg of water with the formula amount into a solution A at the temperature of 50 ℃, and preserving heat;

(2) preparing 0.77kg of hydrogen peroxide, 0.23kg of potassium sulfite and 6kg of water into a solution B;

(3) dropwise adding the solution B in the step (2) into the solution A in the step (1), heating to 60 ℃, carrying out heat preservation reaction for 2 hours, cooling to 30 ℃, and adding a sodium hydroxide solution to adjust the pH value of the reaction solution to 6.5;

(4) and (3) adding 5kg of polyethylene glycol, 5kg of mesoporous molecular sieve, 1kg of micron-sized shell powder and 3kg of pumice powder into the reaction solution obtained in the step (3), and uniformly stirring and mixing to obtain the antifreezing agent.

Preparation example 2 of antifreeze

(1) Preparing 25kg of calcium nitrite, 12kg of cationic polyacrylamide, 7kg of urea, 16kg of sodium lignosulphonate and 32kg of water with the formula amount into a solution A at the temperature of 55 ℃, and preserving heat;

(2) preparing 1.67kg of potassium persulfate, 1.33kg of potassium thiosulfate and 8kg of water into a solution B;

(3) dropwise adding the solution B in the step (2) into the solution A in the step (1), heating to 62 ℃, preserving heat, reacting for 1.5h, cooling to 35 ℃, and adding a sodium hydroxide solution to adjust the pH value of the reaction solution to 7.5;

(4) and (4) adding 8kg of polyethylene glycol, 6.5kg of mesoporous molecular sieve, 3kg of micron-sized shell powder and 6kg of pumice powder into the reaction liquid obtained in the step (3), and uniformly stirring and mixing to obtain the antifreezing agent.

Preparation example 3 of antifreeze

(1) Preparing 30kg of calcium nitrite, 15kg of cationic polyacrylamide, 8kg of urea, 20kg of sodium lignosulphonate and 40kg of water with the formula amount into a solution A at the temperature of 60 ℃, and preserving heat;

(2) preparing 2.27kg of ammonium persulfate, 2.73kg of oxalic acid and 10kg of water into a solution B;

(3) dropwise adding the solution B in the step (2) into the solution A in the step (1), heating to 65 ℃, preserving heat, reacting for 1h, cooling to 40 ℃, and adding a sodium hydroxide solution to adjust the pH value of the reaction solution to 7;

(4) and (3) adding 10kg of polyethylene glycol, 8kg of mesoporous molecular sieve, 5kg of micron-sized shell powder and 8kg of pumice powder into the reaction solution obtained in the step (3), and uniformly stirring and mixing to obtain the antifreezing agent.

Example 1

206kg of cement, 982kg of broken stone, 358kg of river sand, 52kg of fly ash, 50kg of silicon micropowder, 75kg of mineral powder, 10kg of hollow glass microsphere, 10kg of bentonite, 4kg of water reducing agent, 10kg of antifreezing agent provided in the antifreezing agent preparation example 1 and 182kg of water are mixed and stirred uniformly.

Example 2

257kg of cement, 1010kg of broken stone, 389kg of river sand, 60kg of fly ash, 65kg of silicon micropowder, 83kg of mineral powder, 15kg of hollow glass microsphere, 12kg of bentonite, 6kg of water reducing agent and 15kg of antifreezing agent provided in the antifreezing agent preparation example 2 and 194kg of water are mixed and stirred uniformly.

Example 3

289kg of cement, 1040kg of broken stone, 442kg of river sand, 68kg of fly ash, 75kg of silicon micropowder, 96kg of mineral powder, 20kg of hollow glass microspheres, 15kg of bentonite, 7kg of water reducing agent, 20kg of antifreezing agent provided in the antifreezing agent preparation example 3 and 226kg of water are mixed and stirred uniformly.

Comparative example 1

289kg of cement, 1040kg of broken stone, 442kg of river sand, 68kg of fly ash, 75kg of silica micropowder, 96kg of mineral powder, 20kg of hollow glass beads, 15kg of bentonite, 7kg of water reducing agent and 226kg of water are mixed and stirred uniformly.

Comparative example 2

257kg of cement, 1010kg of broken stone, 389kg of river sand, 60kg of fly ash, 65kg of silica micropowder, 83kg of mineral powder, 6kg of water reducing agent, 15kg of common anti-freezing agent and 194kg of water are mixed and stirred uniformly. Wherein the common antifreezing concrete is commercially available.

In order to study the anti-freezing performance and mechanical performance of the concrete obtained in examples 1-3 and comparative examples 1-2, the concrete obtained in examples 1-3 and comparative examples 1-2 was prepared into a test block, and then the test block was cured at a negative temperature of (-5 ℃, -10 ℃, -15 ℃) for 7 days, and after the curing period, the mechanical performance of the frozen concrete test block was tested according to the standard of general concrete mechanical performance test methods (GB/T50081-2001), and the test results are shown in Table 1.

TABLE 1 mechanical Property test results

As shown in Table 1, the filling of the antifreezing agent in the concrete can effectively reduce the freezing point of the concrete, reduce the construction temperature of the concrete, and inhibit the water freezing in the hydration process of the concrete, so that the concrete can be prevented from generating cracks due to the freezing and expansion of the hydration water, and the concrete has higher compressive strength in the low-temperature environment. The antifreezing agent provided by the invention is a composite antifreezing agent, cationic polyacrylamide and sodium lignosulfonate are added on the basis of adding calcium nitrite, urea and polyethylene glycol which are active ingredients of a common antifreezing agent, so that substances containing cations can be decomposed and can be adsorbed to the surface of clay in a limited way, the adsorption of soil and stone powder on the active ingredients of the antifreezing agent and additives is reduced, and the hydration effect of cement is improved.

In order to further study the frost resistance of the concrete, the concrete test blocks obtained in examples 1-3 and comparative examples 1-2 were subjected to a relative dynamic modulus of the test block of the active powder concrete plate measured at intervals of 50 cycles by using a DR-2 type full-automatic rapid freeze-thaw machine and a DT-10W dynamic modulus tester, wherein the dynamic modulus of elasticity was measured by a tapping method using a JS-II type dynamic modulus tester, and the test results are shown in Table 2.

TABLE 2 relative dynamic elastic modulus of concrete test block at different freezing-thawing cycle times

As can be seen from Table 2, after 300 times of freeze-thaw cycle, the relative dynamic elastic modulus of the test blocks of examples 1-3 is still higher, and is more than 93%, and is higher than that of comparative examples 1-2, which shows that the antifreeze agent provided by the invention can effectively reduce the freezing point of concrete mortar, improve the frost resistance of concrete at negative temperature, enable the concrete to form an early structure adapted to hydration, increase the activation energy of water, accelerate the reaction speed of water and cement at negative temperature, and enable the antifreeze concrete of the invention to be suitable for the temperature change in high and cold areas and be constructed at low temperature. Meanwhile, the bentonite and the silicon micropowder are added, so that the effective strength and the viscosity characteristic of the concrete are effectively improved, the combination degree of all components in the concrete is enhanced, and the concrete structure is compact, so that the freeze-thaw resistance of the anti-freezing concrete is excellent, and the durability is good.

Claims

1. An antifreezing concrete is characterized by comprising, by weight, 289 parts of cement 206-; the antifreezing agent comprises, by weight, 20-30 parts of calcium nitrite, 10-15 parts of cationic polyacrylamide, 5-8 parts of urea, 12-20 parts of sodium lignosulfonate, 1-5 parts of an initiator, 1-5 parts of micron-sized shell powder, 5-8 parts of a mesoporous molecular sieve, 5-10 parts of polyethylene glycol, 3-8 parts of pumice powder and 30-50 parts of water.

2. The antifreeze concrete of claim 1, wherein the initiator comprises an oxidizing agent and a reducing agent in a mass ratio of 1: 0.3-1.2.

3. The antifreeze concrete of claim 2, wherein the oxidant is at least one selected from hydrogen peroxide, potassium persulfate and ammonium persulfate; the reducing agent is at least one selected from potassium sulfite, potassium thiosulfate and oxalic acid.

4. The antifreeze concrete of claim 1, wherein the antifreeze agent is prepared by the steps of:

(1) preparing solution A from calcium nitrite, cationic polyacrylamide, urea, sodium lignin sulfonate and 4/5 formula amount of water at 50-60 deg.C, and keeping the temperature;

5. The antifreeze concrete of claim 1, wherein the micron-sized shell powder has a particle size of 1 to 3 μm.

6. The antifreeze concrete as claimed in claim 1, wherein the mineral powder is S95 grade blast furnace slag powder.

7. The antifreeze concrete of claim 1, wherein the expanding agent is an azodicarbonamide plastic expanding agent.

8. The antifreeze concrete of claim 1, wherein the content of the spherical glass bodies in the fly ash is more than 70%, the particle sizes of the spherical glass bodies are continuously distributed and are less than or equal to 3 μm, and the water demand ratio is not more than 95%.

9. The antifreeze concrete of claim 1, wherein the water reducing agent is a polycarboxylic acid water reducing agent.