High-flowability filling mortar with large amount of fly ash and preparation method thereof

Abstract

The application discloses a high-flowability filling mortar with a large amount of fly ash and a preparation method thereof. The high-flowability filling mortar is prepared from the following components in parts by weight: fly ash 425-595 parts, silicate cement 170-250 parts, quicklime 17-40 parts, sand 200-280 parts, water 100 parts, naphthalene sulfonate formaldehyde condensate 5-10 parts, triethanolamine 3-7 parts, polyacrylamide 1-5 parts, calcium formate 2-3 parts and ethylenediaminetetraacetic acid disodium 2-3 parts. The high-flowability filling mortar can shorten the setting time, reduce the hydration heat and greatly reduce the influence of the sand silt content on the performance of the mortar, and meets the filling demand of the mortar in underground engineering construction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underground engineering filling, and particularly relates to a high-flowability filling mortar with a large amount of fly ash and a preparation method thereof. BACKGROUND

[0002] The statements herein are provided only to complement the background of the present application and are not necessarily indicative of the prior art.

[0003] The filling mortar is a main material for grouting filling in underground engineering construction, and currently, the filling mortar mainly uses sand as the main material, but the quality of sand on the market is uneven, and there is a problem of high clay content, which reduces the strength of the filling mortar, increases the dry shrinkage of the mortar, reduces the impermeability of the filling mortar, and has an influence on the regulation performance of the superplasticizer, resulting in poor regulation effect of the water reducing agent. In addition, the filling mortar used on the market currently also has problems of slow setting time and serious hydration heat. SUMMARY

[0004] In view of the problems in the prior art, the present application aims to provide a high-flowability filling mortar with a large amount of fly ash and a preparation method thereof, which can shorten the setting time, reduce the hydration heat, and greatly reduce the influence of the clay content of sand on the performance of the mortar, and meet the needs of the mortar filling in underground engineering construction.

[0005] In order to achieve the above-mentioned purpose, the present application is implemented by the following technical scheme:

[0006] In the first aspect, the present application provides a high-flowability filling mortar with a large amount of fly ash, which is composed of the following components by weight: fly ash 425-595 parts, Portland cement 170-250 parts, quicklime 17-40 parts, sand 200-280 parts, water 100 parts, naphthalene sulfonate formaldehyde condensate 5-10 parts, triethanolamine 3-7 parts, polyacrylamide 1-5 parts, calcium formate 2-3 parts, and ethylenediaminetetraacetic acid disodium 2-3 parts.

[0007] The functions of the components in the filling mortar are as follows:

[0008] Fly ash: The fly ash has a micro-bead shape effect and a micro-aggregate effect, which can enhance the fluidity of the slurry, reduce the amount of cement, enhance the compactness of the slurry, improve the strength of the slurry, and improve the impermeability of the slurry.

[0009] For large volume concrete buildings, such as large volume cement dam, super long cast-in-place pile, super high-rise building foundation slab, etc., a large amount of concrete is needed for on-site pouring, and a large amount of heat is generated during the hydration process of the commonly used cement, which causes thermal strain and internal damage, thereby causing material degradation and even destruction, which can cause great harm to the service life and safety of the related buildings. The "Large Volume Concrete Construction Standard" (GB50496-2018) also puts forward strict requirements for temperature control during the construction process of large volume concrete. In addition, using a large amount of fly ash to replace cement can reduce water consumption to a certain extent, which has significant environmental protection significance and economic benefits for projects in water-scarce or water-deficient areas.

[0010] In the present application, by adjusting the proportion of each component of the filling mortar, a large amount of fly ash can be added to ensure that the slurry meets the requirements of the specification, without increasing the cost of the slurry, while reducing the proportion of cement in the slurry ratio, effectively reducing the generation of slurry hydration heat.

[0011] Quicklime: has weak alkalinity, has an excitation and promotion effect on fly ash material hydration, and promotes the slurry to quickly increase the strength to the required value.

[0012] Sand: as a filling aggregate of the slurry, provides part of the slurry strength.

[0013] Naphthalene sulfonate formaldehyde condensate: belongs to a superplasticizer, which improves the fluidity of the slurry.

[0014] Triethanolamine: can form a complex with cementitious materials, improve the workability of the slurry, accelerate the setting speed of the slurry, and shorten the setting time.

[0015] Polyacrylamide: has lubricity, improves the plasticity of the slurry.

[0016] Calcium formate: promotes the rapid formation of hydrated calcium silicate, accelerates the setting speed of the slurry, and shortens the setting time.

[0017] Disodium ethylenediaminetetraacetate: can preferentially adsorb on the surface of soil particles to form a complex, preventing the adsorption of superplasticizer on the surface of soil particles, and improving the efficiency of superplasticizer.

[0018] In some embodiments, the specific surface area of the Portland cement is greater than 360 m 2 / kg.

[0019] Preferably, the setting time of the Portland cement is 5-20 min when the water-cement ratio is 0.5.

[0020] In some embodiments, the average specific surface area of the fly ash is 450 m 2 / kg.

[0021] In some embodiments, the quicklime has a particle size of 2-4 mm.

[0022] In some embodiments, the sand is medium sand.

[0023] In some embodiments, the naphthalene sulfonate formaldehyde condensate powder is brownish-yellow in color, has an effective content of more than 94%, a paste fluidity greater than 230 mm, a chloride ion content of less than 0.5%, and a pH value of 7-9 for a 1% aqueous solution, where % is a mass percentage.

[0024] In some embodiments, the molecular weight of the polyacrylamide is 10 million to 18 million.

[0025] Secondly, the present invention provides a method for preparing the high-fluidity filling mortar with a large amount of fly ash, comprising the following steps:

[0026] After mixing the components in the specified proportions, a high-fluidity filling mortar with a large amount of fly ash is obtained.

[0027] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0028] This invention discloses a high-fluidity fly ash-based high-fluidity backfill mortar and its preparation technology. The preparation of this material includes the following materials and steps: fly ash, silicate cement, quicklime, sand, water, naphthalenesulfonate formaldehyde condensate, triethanolamine, polyacrylamide, calcium formate, and disodium ethylenediaminetetraacetate. These materials are mixed according to specific mass ratios to ultimately form the high-fluidity fly ash-based high-fluidity backfill mortar and its preparation method. Applying this invention can shorten setting time, reduce heat of hydration, and significantly reduce the impact of sand mud content on mortar performance, meeting the backfill mortar requirements for underground engineering construction. Detailed Implementation

[0029] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] The present invention will be further described below with reference to the embodiments.

[0031] Example 1

[0032] A high-fluidity filling mortar with a large amount of fly ash comprises, by weight, 425 parts fly ash, 170 parts silicate cement, 17 parts quicklime, 200 parts sand, 100 parts water, 5 parts naphthalene sulfonate formaldehyde condensate, 3 parts triethanolamine, 2 parts polyacrylamide, 2 parts calcium formate, and 2 parts disodium ethylenediaminetetraacetate.

[0033] After mixing the components in proportion, a high-fluidity filling mortar with a large amount of fly ash is formed.

[0034] The slurry prepared according to the above proportions has an initial setting time of 30s, a final setting time of 30min, a 3-day compressive strength of 7MPa, a 28-day compressive strength of 11.2MPa, a truncated cone mold diameter of 18cm, and a hydration heat rise of 50℃.

[0035] Hydration heat measurement test procedure:

[0036] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0037] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0038] (3) Heat of hydration temperature = final temperature - initial temperature.

[0039] Example 2

[0040] A high-fluidity filling mortar with a large amount of fly ash, comprising, by weight, 500 parts fly ash, 200 parts silicate cement, 30 parts quicklime, 240 parts sand, 100 parts water, 8 parts naphthalene sulfonate formaldehyde condensate, 5 parts triethanolamine, 3 parts polyacrylamide, 2 parts calcium formate, and 2 parts disodium ethylenediaminetetraacetate.

[0041] After mixing the components in proportion, a high-fluidity filling mortar with a large amount of fly ash is formed.

[0042] The filling mortar prepared according to the above proportions has an initial setting time of 20s, a final setting time of 20min, a 3-day compressive strength of 8.2MPa, a 28-day compressive strength of 14MPa, a truncated cone mold diameter of 20cm, and a hydration heat rise of 45℃.

[0043] Hydration heat measurement test procedure:

[0044] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0045] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0046] (3) Heat of hydration temperature = final temperature - initial temperature.

[0047] Example 3

[0048] A high-fluidity filling mortar with a large amount of fly ash comprises, by weight, 580 parts fly ash, 230 parts silicate cement, 30 parts quicklime, 240 parts sand, 100 parts water, 9 parts naphthalene sulfonate formaldehyde condensate, 5 parts triethanolamine, 3 parts polyacrylamide, 3 parts calcium formate, and 3 parts disodium ethylenediaminetetraacetate.

[0049] The components are mixed in proportion to form a high-fluidity filling mortar with a large amount of fly ash.

[0050] The filling mortar prepared according to the above proportions has an initial setting time of 20s, a final setting time of 20min, a 3-day compressive strength of 9MPa, a 28-day compressive strength of 15MPa, a truncated cone mold diameter of 21cm, and a hydration heat rise of 35℃.

[0051] Hydration heat measurement test procedure:

[0052] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0053] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0054] (3) Heat of hydration temperature = final temperature - initial temperature.

[0055] Comparative Example 1

[0056] The difference from Example 3 is that all the fly ash in Example 3 is replaced with silicate cement, while the rest is the same as in Example 3.

[0057] The filling mortar has an initial setting time of 30s, a final setting time of 130min, a 3-day compressive strength of 9.2MPa, a 28-day compressive strength of 11MPa, a truncated cone mold diameter of 16cm, and a hydration heat rise of 75℃.

[0058] Hydration heat measurement test procedure:

[0059] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0060] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0061] (3) Heat of hydration temperature = final temperature - initial temperature.

[0062] Comparative Example 2

[0063] The difference from Example 3 is that the quicklime in Example 3 is omitted, while the rest is the same as Example 3.

[0064] The filling mortar has an initial setting time of 25s, a final setting time of 23min, a 3-day compressive strength of 8MPa, a 28-day compressive strength of 15MPa, a truncated cone mold diameter of 21cm, and a hydration heat rise of 35℃.

[0065] Hydration heat measurement test procedure:

[0066] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0067] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0068] (3) Heat of hydration temperature = final temperature - initial temperature.

[0069] Comparative Example 3

[0070] The difference from Example 3 is that triethanolamine in Example 3 is omitted, but otherwise it is the same as Example 3.

[0071] The filling mortar has an initial setting time of 26s, a final setting time of 25min, a 3-day compressive strength of 9MPa, a 28-day compressive strength of 15MPa, a truncated cone mold diameter of 18cm, and a hydration heat rise of 35℃.

[0072] Hydration heat measurement test procedure:

[0073] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0074] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0075] (3) Heat of hydration temperature = final temperature - initial temperature.

[0076] Comparative Example 4

[0077] The difference from Example 3 is that calcium formate in Example 3 is omitted, while the rest is the same as Example 3.

[0078] The filling mortar has an initial setting time of 24s, a final setting time of 23min, a 3-day compressive strength of 8.3MPa, a 28-day compressive strength of 15MPa, a truncated cone mold diameter of 21cm, and a hydration heat rise of 35℃.

[0079] Hydration heat measurement test procedure:

[0080] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0081] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0082] (3) Heat of hydration temperature = final temperature - initial temperature.

[0083] Comparative Example 5

[0084] The difference from Example 3 is that disodium ethylenediaminetetraacetate in Example 3 is omitted, while the rest is the same as Example 3.

[0085] The filling mortar has an initial setting time of 20s, a final setting time of 20min, a 3-day compressive strength of 9MPa, a 28-day compressive strength of 15MPa, a truncated cone mold diameter of 19cm, and a hydration heat rise of 35℃.

[0086] Hydration heat measurement test procedure:

[0087] (1) The water temperature before the addition of materials was measured using a thermometer as the initial temperature.

[0088] (2) Weigh 100g of material and add it to 40ml of distilled water. Stir well for 3 minutes and use a thermometer to monitor the water temperature at any time. Take the highest value as the final temperature.

[0089] (3) Heat of hydration temperature = final temperature - initial temperature.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-fluidity filling mortar with a large amount of fly ash, characterized in that: It is composed of the following components in parts by weight: 425-595 parts fly ash, 170-250 parts silicate cement, 17-40 parts quicklime, 200-280 parts sand, 100 parts water, 5-10 parts naphthalene sulfonate formaldehyde condensate, 3-7 parts triethanolamine, 1-5 parts polyacrylamide, 2-3 parts calcium formate, and 2-3 parts disodium ethylenediaminetetraacetate.

2. The high-fluidity filling mortar with large fly ash content according to claim 1, characterized in that: It is composed of the following components in parts by weight: 440-590 parts fly ash, 190-240 parts silicate cement, 20-40 parts quicklime, 220-260 parts sand, 100 parts water, 5-8 parts naphthalene sulfonate formaldehyde condensate, 4-7 parts triethanolamine, 3-5 parts polyacrylamide, 2-3 parts calcium formate, and 2-3 parts disodium ethylenediaminetetraacetate.

3. The high-fluidity filling mortar with large fly ash content according to claim 1, characterized in that: The silicate cement has a specific surface area greater than 360 m². 2 / kg.

4. The high-fluidity filling mortar with large fly ash content according to claim 3, characterized in that: The silicate cement has a setting time of 5-20 minutes when the water-cement ratio is 0.

5.

5. The high-fluidity filling mortar with large fly ash content according to claim 1, characterized in that: The average specific surface area of ​​the fly ash is 450 m². 2 / kg.

6. The high-fluidity filling mortar with high fly ash content according to claim 1, characterized in that: The quicklime has a particle size of 2-4 mm.

7. The high-fluidity filling mortar with high fly ash content according to claim 1, characterized in that: The sand is medium sand.

8. The high-fluidity filling mortar with large fly ash content according to claim 1, characterized in that: The pH of a 1% aqueous solution of the naphthalene sulfonate formaldehyde condensate is 7-9, where % is a mass percentage.

9. The high-fluidity filling mortar with large fly ash content according to claim 1, characterized in that: The molecular weight of the polyacrylamide is 10 million to 18 million.

10. The method for preparing high-fluidity fly ash filling mortar according to any one of claims 1-9, characterized in that: Includes the following steps: After mixing the components in the specified proportions, a high-fluidity filling mortar with a large amount of fly ash is obtained.