Sea sand chloride solidifying agent and application method thereof

Abstract

The present application relates to a kind of sea sand chloride solidifying agent and its application method, the solidifying agent includes solidifying agent A and solidifying agent B;The solidifying agent A is proportioned according to the raw material of weight parts as follows: modified hydrotalcite 2~5 parts, ultrafine silica powder 0.05~0.2 parts, water 30~120 parts;The solidifying agent B is proportioned according to the raw material of weight parts as follows: metakaolin 1~4 parts, calcium hydroxide 0.1~0.3 parts, water 45~180 parts.The present application is attached to the surface of sea sand by modified hydrotalcite with ion adsorption effect and forms inner solid layer, can effectively absorb the chloride ion released by sea sand;While using calcium hydroxide to excite metakaolin with sheet shape and form stable outer solid layer, can effectively prevent the shedding of inner solid layer material;The generated hydrated calcium silicate and hydrated calcium aluminate gel can also absorb the chloride ion solidified from the escape of inner solid layer, further improve the chloride ion solidification effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a sea sand chloride solidifying agent and an application method thereof. BACKGROUND

[0002] Using sea sand with good particle shape and low clay content to replace river sand is one of the effective ways to solve the shortage of sand and gravel resources in China. There are harmful substances such as chloride salts in sea sand, which can reduce the durability of concrete structures if directly used. Although the use of sea sand that has been purified and meets the standard requirements is allowed by the state, the phenomenon of concrete structure damage caused by chloride ions is still widespread in actual engineering investigations. This is mainly due to the fact that a large amount of chloride ions still remain in the cracks of the purified sea sand. To solve this problem, common treatment methods include adding materials with chloride ion solidification effect or coating treatment in concrete, such as slag, fly ash, and hydrotalcite, etc. However, there are many problems in actual application, which are summarized as follows:

[0003] (1) The existing application method is to directly add solidifying materials to concrete to achieve chloride ion solidification, and the amount of addition has a great influence on the solidification effect of chloride ions. When the amount of addition is small, the solidification effect is poor, and when the amount of addition increases, the solidification effect increases, but the mechanical properties and working properties of concrete will be adversely affected.

[0004] (2) Although the solidifying materials can solidify chloride ions, they can only solidify the chloride ions released by sea sand, i.e. they cannot effectively block the release and transmission of chloride ions in sea sand. In the areas and pores of concrete where there is no distribution of solidifying materials, they will still become channels for the accumulation and transmission of chloride ions, thereby reducing the durability of concrete.

[0005] (3) Due to long-term immersion in water, there are a lot of organic substances accumulated on the surface of sea sand. Therefore, the existing coating process needs to treat sea sand with water washing and other processes to reduce the falling of coating materials. This undoubtedly increases the application cost of sea sand. Moreover, it is found in actual application that even after water washing and coating, a large amount of coating material will still fall off during the transportation, loading and unloading, and stirring process of preparing cement-based materials, reducing the solidification effect on chloride ions. SUMMARY

[0006] In order to solve the problems existing in the prior art, the application provides a sea sand chloride solidifying agent and an application method thereof, which forms a uniform and continuous inner solid layer and an outer solid layer on the surface of sea sand, thereby effectively adsorbing the chloride ions released by sea sand.

[0007] To achieve the above-mentioned purposes, the application adopts the following technical solutions:

[0008] A kind of sea sand chloride solidifying agent, the solidifying agent includes solidifying agent A and solidifying agent B;The raw material ratio of solidifying agent A by weight parts is as follows: modified hydrotalcite 2~5 parts, ultrafine silica powder 0.05~0.2 parts, water 30~120 parts;The raw material ratio of solidifying agent B by weight parts is as follows: metakaolin 1~4 parts, calcium hydroxide 0.1~0.3 parts, water 45~180 parts.

[0009] The modified hydrotalcite is high-temperature calcination to hydrotalcite;Specific method is to place hydrotalcite into muffle furnace, heated to 500 DEG C at 5 DEG C / min and calcined for 3h to obtain.

[0010] The particle size of metakaolin is less than 60 μm.The particle size of ultrafine silica powder is not more than 10 μm.

[0011] A kind of sea sand chloride solidifying agent application method, as follows:

[0012] Step one: modified hydrotalcite and ultrafine silica powder are placed in water, and solidifying agent A is prepared by ultrasonic dispersion;Calcium hydroxide is placed in water and stirred for 2~5 min, then metakaolin is added and ultrasonic dispersion is prepared to obtain solidifying agent B;

[0013] Step two: sea sand is poured into the pool containing solidifying agent A, stirred and dispersed, and then placed for 3~8 min, solidifying agent A is attached to the surface and crack of sea sand to form the inner solid layer of adsorbing chloride ion;

[0014] Step three: sea sand is taken out and placed in stirring device, solidifying agent B is sprayed while stirring, and solidifying agent B is attached to the surface of inner solid layer to form outer solid layer with the protection of inner solid layer and the effect of solidifying chloride ion;

[0015] Step four: after curing treatment, sea sand is conveyed to stockyard and dried for 10~24 h, and can be used.

[0016] The amount of solidifying agent A and solidifying agent B is 4~10 L and 3~8 L per ton of sea sand respectively.

[0017] The flow rate of each spray head during spraying is 2~6 L / min.

[0018] The frequency and time of ultrasonic dispersion in step one are 20~40 KHz and 8~15 min.

[0019] Compared with prior art, the beneficial effects of the present application are:

[0020] 1.The present application adopts modified hydrotalcite with anion adsorption effect to adhere to the surface of sea sand to form an internal solid layer, which can effectively adsorb the chlorine ions released from sea sand; the spherical ultra-fine silica powder is dispersed at the same time as the modified hydrotalcite to prepare a curing agent A, which can improve the dispersion degree of the modified hydrotalcite and the adhesion effect on the surface of sea sand, ensure the formation of a uniform and continuous internal solid layer of the modified hydrotalcite, reduce the escape channel of chlorine ions in sea sand, and thus significantly inhibit the transmission of chlorine ions in sea sand in concrete.

[0021] 2.The present application uses calcium hydroxide to excite the sheet-like metakaolin to form a stable external solid layer, which can effectively prevent the internal solid layer material from falling off; the generated hydrated calcium silicate and hydrated calcium aluminate gel can also adsorb the chlorine ions cured from the internal solid layer, further improving the curing effect of chlorine ions. In addition, the curing treatment method of the present application does not need to wash the sea sand before coating, which reduces the process and cost of curing treatment. DETAILED DESCRIPTION

[0022] The present application provides a sea sand chlorine ion curing agent and its application method. In order to further illustrate the technical means and effects adopted by the present application, the present application will be described in detail below in combination with specific embodiments.

[0023] In this embodiment, a sea sand chlorine ion curing agent, the curing agent includes curing agent A and curing agent B; the raw material ratio of the curing agent A by weight parts is: modified hydrotalcite 2-5 parts, ultra-fine silica powder 0.05-0.2 parts, water 30-120 parts; the raw material ratio of the curing agent B by weight parts is: metakaolin 1-4 parts, calcium hydroxide 0.1-0.3 parts, water 45-180 parts.

[0024] The modified hydrotalcite is calcined at high temperature. The specific method is to put the hydrotalcite into a muffle furnace, heat to 500℃ at a heating rate of 5℃ / min and calcine for 3h to obtain.

[0025] The particle size of the metakaolin is less than 60μm. The particle size of the ultra-fine silica powder is not more than 10μm.

[0026] The application method of a sea sand chlorine ion curing agent is as follows:

[0027] Step one: the modified hydrotalcite and the ultra-fine silica powder are placed in water, and the curing agent A is prepared by ultrasonic dispersion; the calcium hydroxide is placed in water and stirred for 2-5min, and then the metakaolin is added and ultrasonically dispersed to prepare the curing agent B;

[0028] Step two: the sea sand is poured into a pool containing the curing agent A, stirred and dispersed, and then placed for 3-8min, the curing agent A adheres to the surface and cracks of the sea sand to form an internal solid layer that adsorbs chlorine ions;

[0029] Step three: the sea sand is fished out and placed in a stirring device, and the curing agent B is sprayed while stirring, and the curing agent B is attached to the surface of the inner curing layer to form an outer curing layer with the functions of protecting the inner curing layer and curing the chloride ions;

[0030] Step four: the sea sand after curing treatment is transported to the yard for airing for 10-24h and can be used.

[0031] The amount of the curing agent A and the curing agent B is 4-10L and 3-8L per ton of sea sand, respectively.

[0032] The flow rate of each spray head during spraying is 2-6L / min.

[0033] The frequency and time of ultrasonic dispersion are 20-40KHz and 8-15min, respectively.

[0034] Example 1:

[0035] 3 parts by weight of modified hydrotalcite and 0.08 parts by weight of superfine silica powder are placed in 55 parts by weight of water, and ultrasonic dispersion is carried out for 10 minutes to obtain the curing agent A; 0.15 parts by weight of calcium hydroxide is placed in 80 parts by weight of water and stirred for 3min, and then 2 parts by weight of metakaolin is added and ultrasonic dispersion is carried out to prepare the curing agent B; 20kg of sea sand is poured into a pool containing the curing agent A and stirred and dispersed, and then placed for 6min; the sea sand is fished out and placed in a stirring device, and the curing agent B is sprayed while stirring; the sea sand is transported to the yard for airing for 12h. The amount of the curing agent A and the curing agent B is 8L and 3L per ton of sea sand, respectively.

[0036] Comparative Example 1:

[0037] 20kg of sea sand without treatment.

[0038] Comparative Example 2:

[0039] 3 parts by weight of modified hydrotalcite and 0.08 parts by weight of superfine silica powder are placed in 55 parts by weight of water, and ultrasonic dispersion is carried out for 10 minutes to obtain the curing agent A; 20kg of sea sand is poured into a pool containing the curing agent A and stirred and dispersed, and then placed for 6min; the sea sand is transported to the yard for airing for 12h. The amount of the curing agent A is 8L per ton of sea sand.

[0040] Comparative Example 3:

[0041] 3 parts by weight of modified hydrotalcite is placed into 55 parts by weight of water, and ultrasonic dispersion is carried out for 10 minutes to obtain a solidifying agent A; 0.15 parts by weight of calcium hydroxide is placed into 80 parts by weight of water, and stirring is carried out for 3 minutes, then 2 parts by weight of metakaolin is added and ultrasonic dispersion is carried out to prepare a solidifying agent B; 20 kg of sea sand is poured into a pool containing the solidifying agent A, and stirring and dispersion are carried out, then the sea sand is placed into a stirring device after standing for 6 minutes, and the solidifying agent B is sprayed while stirring; the sea sand is conveyed to a stockyard and is dried for 12 hours. The amounts of the solidifying agent A and the solidifying agent B are respectively 8 L and 3 L per ton of sea sand.

[0042] The sea sand chloride solidification effect is determined by the following method: 500 g of dry sand is weighed into a grinding bottle, 500 mL of distilled water is injected into the grinding bottle, the bottle is shaken once after being capped, and then is placed for 2 hours, then is shaken once every 5 minutes, a total of 3 times; the solution is filtered, and the chloride ion content in deionized water is obtained by potentiometric titration. The test results of example 1, comparative example 1, comparative example 2 and comparative example 3 are respectively: 0.031 wt%, 0.162 wt%, 0.085 wt%, 0.054 wt%.

[0043] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent changes and modifications within the technical range disclosed by the present application, and the changes and modifications shall fall within the protection scope of the present application.

Claims

1. A method for applying a chloride ion curing agent for sea sand, characterized in that: The curing agent includes curing agent A and curing agent B; the raw material ratio of curing agent A by weight is: 2-5 parts modified hydrotalcite, 0.05-0.2 parts ultrafine silica powder, and 30-120 parts water; the raw material ratio of curing agent B by weight is: 1-4 parts metakaolin, 0.1-0.3 parts calcium hydroxide, and 45-180 parts water. The modified hydrotalcite is prepared by high-temperature calcination of hydrotalcite; specifically, hydrotalcite is placed in a muffle furnace, heated to 500°C at a heating rate of 5°C / min, and calcined for 3 hours. The particle size of the metakaolin is less than 60 μm; The particle size of the ultrafine silicon powder is no greater than 10 μm; The application method of the aforementioned sea sand chloride ion curing agent includes the following steps: Step 1: Modified hydrotalcite and ultrafine silica powder are placed in water and ultrasonically dispersed to prepare curing agent A; calcium hydroxide is placed in water and stirred for 2-5 minutes, then metakaolin is added and ultrasonically dispersed to prepare curing agent B; Step 2: Pour the sea sand into a water tank containing curing agent A, stir and disperse, and let it stand for 3-8 minutes. Curing agent A adheres to the surface and cracks of the sea sand to form an inner solid layer that adsorbs chloride ions. Step 3: Take out the sea sand and put it into the mixing device. While mixing, spray the curing agent B. The curing agent B adheres to the surface of the inner solid layer to form an outer solid layer that protects the inner solid layer and cures chloride ions. Step 4: Transport the cured sea sand to the material yard and let it dry for 10-24 hours before use.

2. The application method of the sea sand chloride ion curing agent according to claim 1, characterized in that: The amounts of curing agent A and curing agent B are 4~10L and 3~8L per ton of sea sand, respectively.

3. The application method of the sea sand chloride ion curing agent according to claim 1, characterized in that: The flow rate of each nozzle during spraying is 2~6L / min.

4. The application method of the sea sand chloride ion curing agent according to claim 1, characterized in that: The frequency and time of the ultrasonic dispersion are 20~40KHz and 8~15min.