CN1087009C - Efficient water-reducing, slow-settling plasticizing agent of concrete - Google Patents

Abstract

A high-efficiency water-reducing, retarding and plastic-preserving agent for concrete, which is compounded by retarding and plastic-preserving components such as aminotrimethylphosphonic acid (ATMP) and water-reducing components such as β-naphthalenesulfonate formaldehyde condensate, to replace the original The water-reducing retarder composed of retarding components such as sugars, acids and inorganic salts and water-reducing components can not only significantly reduce the slump loss of freshly mixed concrete, but also improve the compatibility between cement and admixtures. And can improve the mechanical properties and durability of hardened concrete. This concrete admixture is especially suitable for preparing large-volume concrete, commercial concrete and various high-performance concrete that are constructed under high temperature conditions.

Description

High-efficiency water-reducing, setting-retarding and plastic-retaining agent for concrete

The invention relates to a high-efficiency water-reducing, setting-retarding and plastic-preserving agent for concrete, also known as a concrete admixture (plastic-preserving agent) code-named N-2000, which belongs to the field of building materials.

In order to improve the working performance of freshly mixed concrete, increase the strength and durability of concrete, the application of high-efficiency water reducing agent in concrete is becoming more and more common. It has become another component of modern concrete following the three major components of cement, aggregate and water. Material. However, due to the compatibility of high-efficiency water reducers and cement, the reduction of concrete water-cement ratio, long-distance transportation of concrete, and construction under high temperature conditions, it is easy to cause the slump loss of fresh concrete, which directly affects Quality of Concrete Works (P.C. Aitcin, High Performance Concrete Science and Technology, Published by E&FN Spon 1997).

In the past concrete construction, the following two measures were often adopted to solve the slump loss of freshly mixed concrete (Feng Naiqian, High Performance Concrete, China Architecture and Architecture Press, 1996): one is to add high-efficiency water reducer while adding retarding Coagulants, commonly used retarders are lignosulfonates (such as wood calcium), sugars (such as sugar calcium or sugar), acids (such as sulfosalicylic acid), salts (such as sulfosalicylic acid Sodium, sodium tripolyphosphate, sodium hexametaphosphate, etc.); the second is to increase the amount of cement slurry in concrete to increase the initial slump of fresh concrete, so as to compensate for the loss of fresh concrete slump. These two methods all have problems in technology and economy. The former delays the initial setting time of fresh concrete by adding retarders to reduce the slump loss of fresh concrete. Under air temperature conditions, the effect of inhibiting the slump loss of fresh concrete is not obvious, or even invalid, and it will lead to a decrease in the early strength of hardened concrete; in addition, adding a variety of admixtures in the concrete production process is not convenient for quality control. The increase in the amount of cement slurry in the latter is not only economically unreasonable, but also seriously affects the durability of concrete. Solving the problem of slump loss of freshly mixed concrete must not be at the cost of sacrificing the durability of concrete.

The purpose of the present invention is: in order to overcome the slump loss of freshly mixed concrete and concrete production process by adding a variety of retarders to cause concrete performance reduction, more to solve the existing problem of adding a variety of retarders and delaying the delay under high temperature conditions. The slump loss effect of freshly mixed concrete is not obvious, and an economical, applicable and efficient concrete water-reducing and plastic-retarding agent that can overcome the above-mentioned shortcomings is sought.

In order to realize the purpose of the present invention, the technical measures taken are: aiming at the problems in the application of concrete high-efficiency water reducers, using retarding plastic components such as aminotrimethylene phosphonic acid (ATMP), hydroxyethylidene diphosphonic acid (HEDPA), polyacrylic acid That is, the excellent chelation effect of PAA on calcium and magnesium ions delays the crystallization of the hydration product Ca(OH) ₂ in the cement paste, so as to delay the initial setting time of fresh concrete and keep the slump of fresh concrete within a certain period of time. Basically no loss of purpose. In the present invention, the product codes are FDN, NF, NNO, UNF, AF, SN naphthalenesulfonate formaldehyde condensate series of high-efficiency water reducers, compounding new slow-setting plastic-preserving components ATMP and HEDPA according to a certain proportion and corresponding processes Or PAA, obtained the concrete high-efficiency water-reducing plastic-retarding agent N-2000. In the N-2000 series of high-efficiency water-reducing and plastic-retaining agents, the water-reducing component is 90% to 98%, and the retarding and plastic-preserving component is 2% to 10%. The production process of N-2000 series of high-efficiency water-reducing and plastic-retaining agents is as follows: in the sulfonation or neutralization stage of the production process of high-efficiency water-reducing agents, the retarding and plastic-retaining components are mixed in proportion, and the temperature, pressure and time are equal It is controlled according to the original production process parameters of high-efficiency water-reducing agent; the retarding plastic-retaining component can also be directly compounded with the water-reducing component in proportion to form water agent, the temperature is 10°C-40°C, the pressure is normal pressure, and the concentration of water agent is 10%~40%, vigorously stir for 10min~30min.

Compared with the existing technology, the technical effect achieved by the present invention is that ATMP, HEDPA and PAA are applied to concrete for the first time as retarding and plastic-retaining components, and combined with the above water-reducing components to form the N-2000 series High-efficiency water-reducing and plastic-retarding agent. According to the domestic and international online novelty search of the retrieval center of the Hubei Institute of Science and Technology Information, the technology of the present invention finds that "there is no literature report on the commissioned novelty search item".

The technical performance characteristics of the N-2000 series of high-efficiency water-reducing, retarding and plastic-preserving agents are as follows: 1. The technical performance indicators of the product of the present invention meet the requirements of the first-class product of the national standard GB8076-1997 "Concrete Admixture", and the test results are shown in Table 1. 2 .By adjusting the content of the plastic-retaining component, the product can be adapted to the reasonable construction of concrete in different seasons, which is one of the characteristics that distinguish this product from similar products; Under humidity conditions, the concrete mixture can better achieve the required retarding and plastic-preserving effect, which is another important feature that distinguishes this product from other similar products. 3. When adopting reference cement to add product of the present invention (0.5～1.0%)×C (accounting for the percentage of cement weight), water reducing rate＞18%, the routine dosage of product of the present invention is (0.5～1.0%)×C. 4. The product of the present invention can coordinate the development of concrete water-reducing rate and strength, the early compressive strength of concrete can be increased by more than 25%, and the later strength can develop stably, especially the 90-day strength of concrete still has a larger growth rate compared with the benchmark concrete , the test results are shown in Table 1. 5. According to construction requirements and construction conditions, the setting time of fresh concrete using the product of the present invention is controllable, and the initial setting time of fresh concrete mixed with the product of the present invention is delayed by 3 to 12 hours. The delayed effect of the invented product on the initial setting time of fresh concrete is less affected by the air temperature, and the time difference between initial setting and final setting is basically the same as that of the benchmark concrete, which means that the use of the product of the present invention does not affect the early strength development of concrete. The test results are shown in Table 1. 6. The concrete prepared by using the product of the present invention has the characteristics of large fluidity and high plastic retention. The slump of fresh concrete is generally 150-240mm, when the temperature is 25°C and the relative humidity is 70%, the slump of fresh concrete is basically not lost in 3-4 hours, and the test results are shown in Table 2. 7. The product of the present invention and Cement has good compatibility (adaptability), and the test results are shown in Table 2. 8. The compound performance of the product of the present invention and air-entraining agent is good, such as compounding with air-entraining agents such as rosin thermopolymer, PC-2, DH9s, AEA202 , can give full play to the high-efficiency water-reducing effect of the product of the present invention, the retarding and plastic-preserving effect and the air-entraining effect of the air-entraining agent, that is, there is a synergistic effect produced by compounding. When the two are used in combination, the initial setting time of fresh concrete Use the product of the present invention alone to delay 0.5 to 1.0 hours accordingly. 9. The durability indexes such as frost resistance and impermeability of the concrete mixed with the product of the present invention, for R ₉₀ ¹⁵⁰ D ₁₀₀ S ₈ , mixed with 40% of fly ash, can meet the design requirements at the age of 28 days, and improve the durability of concrete Performance, test result is shown in Table 4. 10. use the concrete of product of the present invention, owing to have reduced the consumption of cementitious material, has reduced the temperature rise of bulky concrete, concrete temperature control and anti-cracking performance are greatly improved, and A certain economic effect can be obtained, and the test results are shown in Table 4.

Table 1 N-2000 test results Sample name N-2000 Dosage 0.6% Testing method GB8076-1997 Cement type Benchmark cement 525# Detection conditions standard temperature Test items Standard first-class product index Test results Water reduction rate ≥12% 19% Bleeding ratio ≤100% 0 Gas content ≤4.5% 0.9% Coagulation time difference (min) initial setting >90 220 final set … 300 compressive strength ratio 3d ≥125% 165% 7d ≥125% 155% 28d ≥120% 141% 90d … 120% shrinkage ratio ≤135% 1 % steel corrosion Indicate that there is no corrosion hazard to the steel bar No rust hazard Conclusion: The test results meet the requirements of the first-class product of the national standard.

Table 2 Comparison of the relationship between the slump of fresh concrete mixed with N-2000 and similar products over time, temperature and cement types Cement type Test temperature Time-dependent changes in slump of fresh concrete mixed with N-2000/mixed with FDN-5 (mm) 0h 1h 2 hours 3 hours 4h Yiye PO 525# 23°C 202/180 185/90 185/15 185/- 180/- 37°C 185/120 180/40 180/- 170/- 125- Zheng Aluminum PO 525# 35°C 170/- 160/- 160/- 165/- - Shayang PO 525# 34°C 165/- 165/- 165/- 160/- - Huaxin PO 525# 34°C 195/165 195/60 185/25 180/- - 36°C 200/- 200/- 210/- 200/- - Jiahua PO 425#R 34°C 180/- 175/- 170/- 165/- - Southern P.II 525# 34°C 200/- 190/- 180/- 170/- - table note The dosage of N-2000 and FDN-5 is 0.8%, the cement dosage is 400-500kg/m ³ , the W/C is 0.34-0.40, the coarse and medium sand, and the gravel D _m is 5-31.5mm.

The following are examples of the present invention, which are only used to illustrate the implementation of the present invention.

Embodiment 1: The technology of the present invention is used to prepare N-2000 high-efficiency water-reducing, setting-retarding and plastic-preserving agent.

At a temperature of 25°C and 1 atm, first weigh 28.8g of FDN powder in a 2000ml clean and dry glass container, then pour 2.4g of ATMP liquid with a solid content of 50% into it, add 968.8g of water, and stir with a glass rod Until the FDN powder is fully dissolved and a uniform solution is formed. The solution is 30% N-2000 high-efficiency water-reducing, coagulation-retarding and plastic-preserving agent.

Embodiment 2: The dam concrete of the Three Gorges Water Conservancy Project is prepared by using the high-efficiency water-reducing, setting-retarding and plastic-retaining agent of Example 1.

Table 3 concrete design parameters Test No. Concrete Design Requirements Grading water-binder ratio Slump (cm) Water consumption(kg/m ³ ) Fly ash (%) Sand rate (%) Admixture (%) Cementitious material (kg/m ³ ) N-2000 DH ₉ cement fly ash 1-3 Dam interior R ₉₀ ¹⁵⁰ D ₁₀₀ S ₃ three 0.55 3-5 104 40 31 0.5 0.012 113 76 1-4 Four 88 26 96 64 2-3 Dam foundation R ₉₀ ²⁰⁰ D ₁₅₀ S ₁₀ three 0.50 102 35 31 0.012 133 71 2-4 Four 88 26 114 62 3-3 ABOVE AND UNDERWATER EXTERIOR R ₉₀ ²⁰⁰ D ₂₅₀ S ₁₀ three 0.50 102 25 30 0.011 153 51 3-4 Four 88 25 132 44 4-3 Outside the water level change area R ₉₀ ²⁵⁰ D ₂₅₀ S ₁₀ three 0.45 104 30 30 0.011 162 69 4-4 Four 90 25 150 50 table note The dosage of N-2000 is calculated by solid content. The data in this table are provided by Yichang Qingyun Water Conservancy and Hydropower Joint Venture Company.

The N-2000 concrete test measured result of table 4 mixing example 1 Test No. Air temperature (℃) Workability of fresh concrete Coagulation time (h: min) Compressive strength (MPa) Tensile strength (MPa) Impermeability grade Antifreeze label Slump (cm) Cohesion Analysis of water initial setting final set 7d 28d 90d 28d 90d 1-3 26 8.0 good few - - 11.8 16.8 29.7 - - >S ₈ >D ₁₀₀ 1-4 27 4.2 good few 13:05 18:45 12.1 20.1 27.8 1.78 2.59 2-3 twenty four 4.3 good few 12:30 17:20 14.0 21.7 33.5 1.08 2.85 >S ₁₀ >D ₁₅₀ 2-4 twenty one 4.4 good few 12:00 18:30 17.6 26.5 39.0 2.65 3.13 3-3 25 6.0 good few - - 20.5 28.2 43.7 2.90 3.29 >S ₁₀ >D ₂₅₀ 3-4 twenty four 3.8 good none 11:10 14:55 20.8 33.1 45.8 2.75 3.28 4-3 twenty two 5.0 good few 10:00 14:40 22.3 33.0 44.7 3.05 3.65 >S ₁₀ >D ₂₅₀ 4-4 twenty three 4.2 good few 14:00 17:30 26.0 39.5 52.6 3.00 3.66 table note The data in this table are provided by the laboratory of Yichang Qingyun Water Conservancy and Hydropower Co., Ltd.

As can be seen from Table 4, adopting the product of the present invention to prepare concrete for the Three Gorges Project, its various performance indicators all exceed the design requirements.

Example 3: China First Metallurgical Construction Company used the N-2000 of Example 1 to prepare a concrete engineering example.

Raw materials: First Metallurgical P.O 525# cement, Bahe medium sand, 5-31.5mm limestone crushed stone, N-2000 content is 0.6% of cement weight. The test results are shown in Table 5.

The N-2000 concrete test measured result of table 5 mixing example 1 Test No. Concrete mix ratio Time-dependent change of slump (mm) Compressive strength (MPa) Water: Cement: Sand: Stone: FDN-9001 0h 1h 2 hours 3 hours 3d 7d 28d 0 0.48:1:1 37:2.56:0 85 - - - 20.4/100 26.4/100 32.8/100 1 0.42:1:1.49:2.44:0.006 190 180 170 160 30.2/148 38.3/145 46.7/142 table note The dosage of N-2000 is based on solid content, the test temperature of slump over time is 35°C, and the compressive strength test is the standard condition.

It can be seen from Table 5 that the N-2000 fresh concrete mixed with Example 1 lost 5% of the slump after 1 hour, 11% in 2 hours, and 16% in 3 hours at 35°C.

Claims (3)

1. A high-efficiency water-reducing plastic-retarding agent using commonly used water-reducing components, characterized in that: it is compounded by industrially pure retarding plastic-retaining components and known water-reducing components; its composition ratio It is: 2%-10% of the retarding plastic-preserving component, and 90%-98% of the water-reducing component; the retarding plastic-preserving component is aminotrimethylene phosphonic acid, hydroxyethylidene diphosphonic acid or polyacrylic acid. 2. A method for producing the high-efficiency water-reducing, retarding, and plastic-preserving agent according to claim 1, characterized in that, during sulfonation or neutralization in the high-efficiency water-reducing agent production process, the retarding and plastic-preserving component is 2% ～10% and 90%～98% of the water-reducing component, the retarding plastic-retaining component is mixed into the water-reducing component, and its temperature, pressure and time are all controlled according to the original production process parameters of the high-efficiency water-reducing agent; or According to the ratio of 2% to 10% of the retarding plastic-preserving component and 90% to 98% of the water reducing component, the water agent is directly compounded into the water agent, the temperature is 10°C to 40°C, the pressure is normal pressure, and the concentration of the water agent is 10%. ~40%, stir vigorously for 10min~30min. 3. The high-efficiency water-reducing, setting-retarding and plastic-retaining agent of claim 1 is used for water-reducing, setting-retarding and plastic-retaining of concrete, mass concrete, commercial concrete and various high-performance concretes constructed under high temperature conditions.