阅读说明：本技术 一种混凝土冬季施工防冻方法 (Concrete winter construction anti-freezing method ) 是由 刘胜男 江鑫 黄周熠 鄢梅梅 陈昌龙 于 2021-09-23 设计创作，主要内容包括：本发明涉及混凝土施工技术领域,尤其是涉及一种混凝土冬季施工防冻方法,包括以下步骤：采用骨料、水泥、水和外加剂制备混凝土；将钢筋放置在待浇筑区域,在钢筋的外周放置加热板,对钢筋进行预热,用混凝土对预热后的钢筋进行浇筑；采用加热板持续加热,使混凝土的温度升高,并在混凝土的表面覆盖保温材料,混凝土逐渐硬化；将加热板停止加热,待混凝土冷却后,拆除加热板和保温材料,获得浇筑件。本发明的技术方案通过加热板对混凝土进行加热,使混凝土在浇筑和养护期间保持较高的温度,防止混凝土在冬季低温环境下受冻损害,避免因天气寒冷而造成的混凝土质量问题,保证混凝土在低温条件下的施工质量。(The invention relates to the technical field of concrete construction, in particular to a concrete winter construction anti-freezing method, which comprises the following steps: preparing concrete by adopting aggregate, cement, water and an additive; placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bars, preheating the steel bars, and pouring the preheated steel bars by using concrete; continuously heating by adopting a heating plate to increase the temperature of the concrete, covering a heat-insulating material on the surface of the concrete, and gradually hardening the concrete; and stopping heating the heating plate, and removing the heating plate and the heat insulation material after the concrete is cooled to obtain the pouring piece. According to the technical scheme, the heating plate is used for heating the concrete, so that the concrete is kept at a higher temperature during pouring and maintenance, the concrete is prevented from being frozen and damaged in a low-temperature environment in winter, the quality problem of the concrete caused by cold weather is avoided, and the construction quality of the concrete under the low-temperature condition is ensured.)

1. The concrete winter construction anti-freezing method is characterized by comprising the following steps of:

s1, putting aggregate and cement into a stirrer for dry mixing, and then adding water and an additive for stirring to obtain concrete;

s2, placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bars, preheating the steel bars by using the heating plates, pouring the preheated steel bars by using the concrete obtained in the step S1, arranging heating elements in the heating plates, and arranging temperature sensors on the heating plates;

s3, continuously heating by adopting a heating plate to increase the temperature of the concrete, covering a heat-insulating material on the surface of the concrete, and gradually hardening the concrete;

and S4, stopping heating the heating plate, and removing the heating plate and the heat insulation material after the concrete is cooled to obtain the pouring piece.

2. The concrete winter construction antifreezing method as claimed in claim 1, wherein in the step S4, the heating plate and the thermal insulation material are removed when the concrete is cooled to a temperature difference between the surface temperature of the concrete and the external temperature of less than 5 ℃.

3. The concrete winter construction antifreezing method as set forth in claim 1, wherein in the step S1, the admixture comprises the following raw materials in parts by weight: 30-40 parts of ethylene glycol, 8-12 parts of grinding wheel ash, 10-15 parts of sodium thiosulfate and 25-30 parts of mesoporous molecular sieve.

4. The concrete winter construction anti-freezing method as claimed in claim 1, wherein the step S3 is: and continuously heating by adopting a heating plate to increase the temperature of the concrete, wherein the temperature increase rate of the concrete is 4-6 h/DEG C, covering a heat insulation material on the surface of the concrete to control the temperature of the concrete to be 20-30 ℃, and carrying out heat insulation to gradually harden the concrete.

5. The concrete winter construction antifreezing method as claimed in claim 4, wherein in the step S3, the thermal insulation material comprises a plastic film and a cotton felt, the plastic film covers the surface of the concrete, and the cotton felt covers the plastic film.

6. The concrete winter construction anti-freezing method according to claim 5, characterized in that in step S3, when the outside temperature is less than or equal to 0 ℃ and less than or equal to 5 ℃, the concrete surface is covered with a layer of plastic film and a layer of cotton felt; when the external temperature is less than or equal to 0 ℃ below zero 5 ℃, covering a layer of plastic film and two layers of cotton felts on the surface of the concrete; when the outside temperature is more than or equal to minus 10 ℃ and less than or equal to minus 5 ℃, the surface of the concrete is covered with a layer of plastic film and three layers of cotton felts.

7. The concrete winter construction antifreezing method as claimed in claim 1, wherein the preheating temperature of the steel bars in step S2 is 5-8 ℃.

8. The concrete winter construction anti-freezing method as claimed in claim 7, wherein in step S2, after the preheated steel bars are poured by the concrete obtained in step S1, the concrete is vibrated for 20-30S, the vibrating distance is 40-50 cm, and the vibrating depth is 80-100 cm.

9. The concrete winter construction antifreezing method as set forth in claim 3, wherein in the step S1, the cement is early strength portland cement, and the additive amount of the admixture is 1-1.5% of the cement.

10. The concrete winter construction anti-freezing method as claimed in claim 9, wherein in step S1, the dry mixing time is 3-5 min, and the stirring time is 9-12 min.

Technical Field

The invention relates to the technical field of concrete construction, in particular to a concrete winter construction anti-freezing method.

Background

The concrete is a composite material prepared by mixing a gel material, an aggregate and water according to a proper proportion and hardening for a certain time, has the characteristics of easiness in molding, high compressive strength, good durability and the like, and is widely applied to infrastructure construction.

The concrete is easily affected by the ambient temperature in the hardening process, particularly in winter and in low-temperature environments, a part of water in the concrete begins to freeze, so that the hydration rate of cement is reduced, the strength of the concrete is slowly increased, ice with large particles is formed on the surfaces of aggregates and reinforcing steel bars after the water turns into ice, the bonding force of cement paste, the aggregates and the reinforcing steel bars is weakened, the compressive strength of the concrete is affected, and various gaps are formed in the concrete after the ice melts, so that the compactness and the durability of the concrete are reduced. Therefore, in order to ensure the construction quality of concrete in a low-temperature environment, an anti-freezing method for concrete construction in winter is urgently needed.

Disclosure of Invention

The invention aims to provide a concrete winter construction anti-freezing method which can prevent concrete from being damaged by freezing in a low-temperature environment in winter, avoid the quality problem of the concrete caused by cold weather and ensure the construction quality of the concrete under the low-temperature condition.

The invention provides a concrete winter construction anti-freezing method, which comprises the following steps:

s1, putting aggregate and cement into a stirrer for dry mixing, and then adding water and an additive for stirring to obtain concrete;

s2, placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bars, preheating the steel bars by using the heating plates, pouring the preheated steel bars by using the concrete obtained in the step S1, arranging heating elements in the heating plates, and arranging temperature sensors on the heating plates;

s3, continuously heating by adopting a heating plate to increase the temperature of the concrete, covering a heat-insulating material on the surface of the concrete, and gradually hardening the concrete;

and S4, stopping heating the heating plate, and removing the heating plate and the heat insulation material after the concrete is cooled to obtain the pouring piece.

Further, in step S4, when the concrete is cooled to a temperature difference between the surface temperature of the concrete and the external temperature of the concrete is less than 5 ℃, the heating plate and the heat insulating material are removed. When concrete cools, the thermal insulation material covering the concrete surface is reserved to prevent the sudden drop of the concrete surface temperature, great tensile stress is caused on the concrete surface, when the tensile stress exceeds the anti-cracking capacity of the concrete, the concrete can crack, the quality of the concrete is affected, when the concrete surface temperature and the external temperature difference are less than 5 ℃, the thermal insulation material is detached, the concrete surface can be prevented from generating tensile stress, and the concrete can be prevented from cracking.

Further, in step S1, the admixture includes the following raw materials in parts by weight: 30-40 parts of ethylene glycol, 8-12 parts of grinding wheel ash, 10-15 parts of sodium thiosulfate and 25-30 parts of mesoporous molecular sieve. The glycol serving as the antifreezing agent can reduce the freezing point of the concrete, so that the concrete can still undergo hydration reaction in a low-temperature environment, and the strength of the concrete is not influenced; the mesoporous molecular sieve has a microporous structure, can be used as a carrier of the ethylene glycol, improves the dispersibility of the ethylene glycol, enables the ethylene glycol to be dispersed in cement paste, increases the contact area with concrete, and further exerts the antifreezing performance of the ethylene glycol; the particle size of the grinding wheel ash is small, the grinding wheel ash can be filled in the pores in the concrete, the compactness of the concrete is improved, the later-period shrinkage is reduced, the grinding wheel ash and the glycol act together, the frost resistance of the concrete is further improved, and meanwhile, the strength of the concrete can also be improved; the sodium thiosulfate can improve the reinforcing speed of the concrete, enable the concrete to be early-strengthened, shorten the hardening time of the concrete, and enable the concrete to achieve higher strength in a shorter time under the combined action of the sodium thiosulfate, the sand wheel ash and the early-strengthening silicate cement.

Further, step S3 is: and continuously heating by adopting a heating plate to increase the temperature of the concrete, wherein the temperature increase rate of the concrete is 4-6 h/DEG C, covering a heat insulation material on the surface of the concrete to control the temperature of the concrete to be 20-30 ℃, and carrying out heat insulation to gradually harden the concrete. By controlling the heating rate of the concrete, the temperature of the concrete is slowly increased, the tensile stress generated in the concrete by the sudden temperature rise of the concrete is avoided, so that cracks are generated in the concrete, the temperature of the concrete is controlled to be between 20 and 30 ℃, the moisture in the concrete is prevented from being frozen into ice under the low-temperature condition, the moisture in the concrete is prevented from evaporating under the low-temperature condition, the hydration effect of the cement is ensured to be carried out normally or accelerated, and the concrete just poured can be hardened normally or accelerated, and the strength of the concrete is increased.

Further, in step S3, the heat insulation material includes a plastic film and a cotton felt, the plastic film covers the surface of the concrete, and the cotton felt covers the plastic film. Cover the plastic film on concrete surface, can make the inside free water of evaporation of concrete accumulate and keep warm the maintenance on concrete surface, cover the heat preservation effect that the cotton felt can strengthen the concrete on plastic film surface, ensure that the concrete can not receive the damage of freezing.

Further, in the step S3, when the external temperature is less than or equal to 5 ℃ below 0 ℃, covering a layer of plastic film and a layer of cotton felt on the surface of the concrete; when the external temperature is less than or equal to 0 ℃ below zero 5 ℃, covering a layer of plastic film and two layers of cotton felts on the surface of the concrete; when the outside temperature is more than or equal to minus 10 ℃ and less than or equal to minus 5 ℃, the surface of the concrete is covered with a layer of plastic film and three layers of cotton felts. According to the temperature condition of a construction site, the number of the covering layers of the cotton felt is selected, so that the heat preservation effect is more excellent.

Further, in step S2, the preheating temperature of the steel bars is 5-8 ℃.

Further, in step S2, after the preheated steel bars are poured by the concrete obtained in step S1, the concrete is vibrated for 20-30S, the vibrating distance is 40-50 cm, and the vibrating depth is 80-100 cm. The method comprises the steps of vibrating poured concrete, removing air bubbles in the concrete, enabling the concrete to be combined in dense chambers, further improving the strength of the concrete, plastering the concrete after vibrating, carrying out first plastering before initial setting of the concrete, carrying out second plastering after initial setting until final setting of the concrete, and closing uneven and irregular cracks on the surface of the concrete.

Further, in step S1, the cement is early strength portland cement, and the addition amount of the additive is 1-1.5% of the cement. The early-strength portland cement has high hydration heat and can shorten the time for increasing the strength of the concrete.

Further, in step S1, the dry mixing time is 3-5 min, and the stirring time is 9-12 min.

The invention has the beneficial effects that:

according to the technical scheme, the heating plate is used for heating the concrete, so that the concrete is kept at a higher temperature during pouring and maintenance, the concrete is prevented from being frozen and damaged in a low-temperature environment in winter, the quality problem of the concrete caused by cold weather is avoided, and the construction quality of the concrete under the low-temperature condition is ensured.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms also include the plural forms unless the context clearly dictates otherwise, and further, it is understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and/or combinations thereof.

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A concrete winter construction anti-freezing method comprises the following steps:

s1, preparing an additive by adopting 1.5Kg of ethylene glycol, 0.4Kg of grinding wheel ash, 0.5Kg of sodium thiosulfate and 1.25Kg of mesoporous molecular sieve, putting 100Kg of early strength portland cement and 383Kg of aggregate into a stirrer, dry-stirring for 3min, then adding 38Kg of water and 1Kg of additive, and stirring for 9min to obtain concrete;

s2, placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bar structures, wherein the heating plates are externally connected with a power supply, arranging electric heating tubes in the heating plates, preheating the steel bars by using the electric heating tubes, pouring the preheated steel bars by using the concrete obtained in the step S1, and arranging waterproof layers on the heating plates to prevent moisture in the concrete from entering the heating plates to cause the electric heating tubes to break down;

s3, after concrete pouring is finished, vibrating the poured concrete for multiple times, wherein the vibrating depth is 80cm each time, so that the combination of the concrete is enhanced, the vibrating time is 20s each time, sand and cement paste are prevented from being separated, stones sink, a sand layer is formed on the surface of the concrete, the quality of the concrete is influenced, the distance between the front and the back of each vibrating is 40cm, vibration leakage is prevented, after the vibrating is finished, the concrete is subjected to primary plastering before initial setting, and during the period from initial setting to final setting, the surface of the concrete is subjected to multiple times, cracks on the surface of the concrete are closed, and then the concrete is subjected to secondary plastering;

s4, after plastering treatment, continuously heating the concrete by adopting a heating plate to enable the temperature of the concrete to rise at a speed of 4 ℃/h, covering a plastic film and a cotton felt on the surface of the concrete to cure the concrete, gradually hardening the concrete, selecting the number of layers covering the cotton felt according to the external temperature, and measuring the temperature of the concrete by a temperature sensor arranged on the heating plate during curing to control the temperature of the concrete to be 20 ℃;

and S5, after the concrete is hardened, stopping heating the heating plate to gradually reduce the temperature of the concrete, taking down the plastic film and the cotton felt on the surface of the concrete when the concrete is cooled to a temperature difference between the surface temperature of the concrete and the external temperature of less than 5 ℃, and removing the heating plate to obtain a pouring piece.

Example 2

A concrete winter construction anti-freezing method comprises the following steps:

s1, preparing an additive by adopting 1.75Kg of ethylene glycol, 0.6Kg of grinding wheel ash, 0.65Kg of sodium thiosulfate and 1.5Kg of mesoporous molecular sieve, putting 100Kg of early strength portland cement and 383Kg of aggregate into a stirrer, dry-stirring for 4min, adding 38Kg of water and 1Kg of additive, and stirring for 11min to obtain concrete;

s2, placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bar structures, wherein the heating plates are externally connected with a power supply, arranging electric heating tubes in the heating plates, preheating the steel bars by using the electric heating tubes, pouring the preheated steel bars by using the concrete obtained in the step S1, and arranging waterproof layers on the heating plates to prevent moisture in the concrete from entering the heating plates to cause the electric heating tubes to break down;

s3, after concrete pouring is finished, vibrating the poured concrete for multiple times, wherein the vibrating depth is 90cm each time to reinforce the combination of the concrete, the vibrating time is 25s each time, sand and cement paste are prevented from being separated, stones sink, a sand layer is formed on the surface of the concrete to influence the quality of the concrete, the distance between the front and the back of each vibrating is 45cm to prevent vibration leakage, after the vibrating is finished, performing first plastering on the concrete before initial setting of the concrete, and performing second plastering on the concrete after the initial setting and during the final setting of the concrete for multiple times on the surface of the concrete to close cracks on the surface of the concrete;

s4, after plastering treatment, continuously heating the concrete by adopting a heating plate to enable the temperature of the concrete to rise at a speed of 5 ℃/h, covering a plastic film and a cotton felt on the surface of the concrete to cure the concrete, gradually hardening the concrete, selecting the number of layers covering the cotton felt according to the external temperature, and measuring the temperature of the concrete by a temperature sensor arranged on the heating plate during curing to control the temperature of the concrete to be 25 ℃;

and S5, after the concrete is hardened, stopping heating the heating plate to gradually reduce the temperature of the concrete, taking down the plastic film and the cotton felt on the surface of the concrete when the concrete is cooled to a temperature difference between the surface temperature of the concrete and the external temperature of less than 3 ℃, and dismantling the heating plate to obtain a pouring piece.

Example 3

A concrete winter construction anti-freezing method comprises the following steps:

s1, preparing an additive by adopting 1.9Kg of ethylene glycol, 0.6Kg of grinding wheel ash, 0.75Kg of sodium thiosulfate and 1.5Kg of mesoporous molecular sieve, putting 100Kg of early strength portland cement and 383Kg of aggregate into a stirrer, dry-stirring for 5min, adding 38Kg of water and 1Kg of additive, and stirring for 12min to obtain concrete;

s2, placing the steel bars in a to-be-poured area, placing heating plates on the peripheries of the steel bar structures, wherein the heating plates are externally connected with a power supply, arranging electric heating tubes in the heating plates, preheating the steel bars by using the electric heating tubes, pouring the preheated steel bars by using the concrete obtained in the step S1, and arranging waterproof layers on the heating plates to prevent moisture in the concrete from entering the heating plates to cause the electric heating tubes to break down;

s3, after concrete pouring is finished, vibrating the poured concrete for multiple times, wherein the vibrating depth is 90cm each time to reinforce the combination of the concrete, the vibrating time is 30s each time, sand and cement paste are prevented from being separated, stones sink, a sand layer is formed on the surface of the concrete to influence the quality of the concrete, the distance between the front and the back of each vibrating is 50cm to prevent vibration leakage, after the vibrating is finished, performing first plastering on the concrete before initial setting of the concrete, and performing second plastering on the concrete after the initial setting and during the final setting of the concrete for multiple times on the surface of the concrete to close cracks on the surface of the concrete;

s4, after plastering treatment, continuously heating the concrete by adopting a heating plate to enable the temperature of the concrete to rise at the speed of 6 ℃/h, covering a plastic film and a cotton felt on the surface of the concrete to cure the concrete, gradually hardening the concrete, selecting the number of layers covering the cotton felt according to the external temperature, and measuring the temperature of the concrete by a temperature sensor arranged on the heating plate during curing to control the temperature of the concrete to be 30 ℃;

and S5, after the concrete is hardened, stopping heating the heating plate to gradually reduce the temperature of the concrete, taking down the plastic film and the cotton felt on the surface of the concrete when the concrete is cooled to a temperature difference between the surface temperature of the concrete and the external temperature of less than 2 ℃, and removing the heating plate to obtain a pouring piece.

Comparative example 1

The concrete winter construction antifreezing method is basically the same as the concrete winter construction antifreezing method in the embodiment 1, and the only difference is that: in step S1, no external additive is added.

Comparative example 2

The concrete winter construction antifreezing method is basically the same as the concrete winter construction antifreezing method in the embodiment 1, and the only difference is that: in step S1, the admixture is composed of urea, grinding wheel dust, and sodium thiosulfate.

Comparative example 3

The concrete winter construction antifreezing method is basically the same as the concrete winter construction antifreezing method in the embodiment 1, and the only difference is that: in step S5, after the heating of the heating plate is stopped, the thermal insulation material on the surface of the concrete is directly removed.

Test example

The compressive strength of the casting obtained in example 1 and the casting obtained in comparative examples 1 to 3 were measured, and the results are shown in table 1.

TABLE 1

Sample (I)	Compressive strength/MPa
		Example 1	31
Example 2	34
		Example 3	36
Comparative example 1	24
		Comparative example 2	28
Comparative example 3	18

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.