A rigid waterproof non-shrinkage anti-crack low-carbon concrete

Abstract

The application discloses a preparation method of low-shrinkage low-heat low-carbon concrete, and has the technical characteristics that high-water-absorption autoclaved silicate functional aggregate is used to replace gravel and yellow sand, and the mass sum of fly ash and mineral powder in the cementing material can be up to 60% at most. The high-water-absorption water-saturated autoclaved silicate functional aggregate and the expanding agent are added into the concrete, the humidity is released through the functional aggregate, the internal curing and the expansion of the expanding agent are cooperated, the self-shrinkage, the drying shrinkage and the hydration heat shrinkage of the concrete are reduced, and the strength of the concrete is improved; the grading of the fine aggregate of the superfine yellow sand is improved through the addition of the fine functional aggregate, the working performance of the concrete is improved, and the low-carbon environmental protection of the concrete is realized through the large amount of mineral admixtures.

Description

Technical Field

[0001] This invention relates to a method for preparing concrete, and more particularly to a method for preparing non-shrink, low-heat, low-carbon concrete using autoclaved silicate functional aggregates and high-volume mineral admixtures. Background Technology

[0002] Cracking of large-volume concrete is a challenging problem in engineering. In densely populated underground structures, such as subway stations, concrete cracking can easily compromise its rigid waterproofing properties, affecting the normal use of the underground space. For open-air structures, harmful corrosive media can erode the concrete through cracks. Therefore, it is necessary to design a novel concrete preparation method to produce non-shrink, crack-resistant concrete while ensuring project quality and without increasing costs.

[0003] Concrete undergoes shrinkage during curing and service due to various factors. When this shrinkage exceeds a certain level, cracking can occur. Numerous studies have shown that when the effective water-cement ratio of concrete is below 0.42, external moisture must be added to prevent autogenous and drying shrinkage. High-performance concrete typically has a water-cement ratio of around 0.34, resulting in significant early autogenous and drying shrinkage, which easily leads to cracking. Furthermore, the heat of hydration released during cement hydration causes the concrete to shrink during cooling; this shrinkage is called thermal shrinkage. When pouring large volumes of concrete, the internal temperature can reach over 80°C due to the heat of hydration, resulting in significant thermal shrinkage and increasing the risk of cracking.

[0004] In engineering, internal curing materials are often used to reduce concrete shrinkage. These materials pre-store moisture, continuously replenishing it during the hardening process and mitigating autogenous and drying shrinkage. The most commonly used internal curing agent is hydroquinone, which has a high water absorption rate. However, hydroquinone leaves pores in the concrete, easily leading to a decrease in strength, thus its dosage is extremely limited. Sintered ceramsite has a very low water absorption rate. Although crushing it can increase the water absorption rate, it significantly reduces its strength as aggregate. Therefore, common internal curing materials are not suitable for preparing high-performance concrete.

[0005] Spherical silicate particles prepared by hydrothermal synthesis using cement, lime, etc. as calcareous materials and fly ash, slag, steel slag, tailings slag, etc. as siliceous raw materials, through batching, mixing, pelletizing, pre-curing, and autoclaving, are called autoclaved silicate functional aggregates. They have a compressive strength greater than 10 MPa, a saturated water absorption rate of 10-30%, and a particle shape coefficient of less than 1.1, and are very promising for the preparation of low-shrinkage and crack-resistant concrete. Summary of the Invention

[0006] This invention provides a non-shrink, crack-resistant low-carbon concrete for rigid waterproofing, comprising the following components in parts by weight:

[0007] Cementitious material: 400-500 parts;

[0008] Natural coarse aggregate: 100-1000 parts;

[0009] Artificial coarse aggregate: 60-900 parts;

[0010] Natural fine aggregate: 300-500 parts;

[0011] Artificial fine aggregate: 60-200 parts;

[0012] Water: 120-170 parts;

[0013] Water-reducing agent: 2-14 parts;

[0014] Expanding agent: 30-40 parts.

[0015] Furthermore, the cementitious material comprises the following components in parts by weight:

[0016] Cement: 160-380 parts;

[0017] Fly ash: 40-200 parts;

[0018] Mineral powder: 40-100 parts.

[0019] Furthermore, it includes the following components in parts by weight:

[0020] Cement: 310-370 parts;

[0021] Fly ash: 40-70 parts;

[0022] Mineral powder: 40-70 parts;

[0023] Natural coarse aggregate: 780–950 parts;

[0024] Artificial coarse aggregate: 60-220 parts;

[0025] Natural fine aggregate: 450-470 parts;

[0026] Artificial fine aggregate: 160-190 parts;

[0027] Water: 130-140 parts;

[0028] Water-reducing agent: 3-4 parts;

[0029] Expanding agent: 35-38 parts.

[0030] Furthermore, the artificial coarse aggregate is autoclaved silicate functional coarse aggregate, and the artificial fine aggregate is autoclaved silicate functional fine aggregate sand.

[0031] Furthermore, the total volume of coarse aggregate accounts for 40% to 50% of the volume of concrete, and the ratio of the volume of artificial coarse aggregate to the total volume of coarse aggregate is 10% to 90%, wherein the total volume of coarse aggregate is the sum of the volumes of natural coarse aggregate and artificial coarse aggregate.

[0032] Furthermore, the ratio of the volume of the artificial fine aggregate to the total volume of the fine aggregate is 10% to 40%, and the total volume of the fine aggregate is the sum of the volumes of the natural fine aggregate and the artificial fine aggregate.

[0033] Furthermore, the mass ratio of water to the cementitious material is 30% to 35%.

[0034] Furthermore, the mass ratio of the expanding agent to the cementitious material is 6% to 12%.

[0035] Furthermore, the particle size of the artificial coarse aggregate or the natural coarse aggregate is 5mm to 20mm, and the particle size of the artificial fine aggregate is 2mm to 4mm.

[0036] Furthermore, the apparent density of the artificial coarse aggregate or the artificial fine aggregate is 1550 kg / m³. 3 ~2150kg / m 3 .

[0037] Furthermore, the mass of the cementitious material is 450 kg / m³. 3 The mass of the cement is 180 kg / m³. 3 ~360kg / m 3 The mass of the fly ash is greater than or equal to 45 kg / m³. 3 The mass of the mineral powder is greater than or equal to 45 kg / m³. 3 .

[0038] Furthermore, the autoclaved silicate functional coarse aggregate and the autoclaved silicate functional fine aggregate sand are produced by hydrothermal synthesis, with a synthesis pressure greater than or equal to 1 MPa, and their 24-hour saturated water absorption rate is 10% to 30%.

[0039] Furthermore, the expanding agent is one or more of magnesium oxide, calcium oxide, calcium sulfoaluminate gypsum type, and alum stone gypsum type expanding agents.

[0040] Furthermore, the particle shape coefficient of the artificial coarse aggregate or the artificial fine aggregate is less than 1.1.

[0041] Beneficial effects

[0042] Compared with existing technologies, the non-shrink, crack-resistant low-carbon concrete for rigid waterproofing of this invention has the following advantages:

[0043] (1) Saturated autoclaved silicate functional aggregates have an internal curing effect, which can continuously replenish the water consumed during the hardening process of concrete and alleviate the autogenous shrinkage and drying shrinkage of concrete. The large amount of mineral admixtures in concrete prolongs the hydration time of concrete and reduces the peak heat of hydration; the high water absorption rate of saturated autoclaved silicate functional aggregates contains a large amount of water inside, and its specific heat capacity is much greater than that of crushed stone. The heat required to rise by one degree is greater than that absorbed by crushed stone, which can reduce the temperature rise rate of concrete; the synergistic effect of the two can significantly reduce the temperature difference shrinkage of concrete.

[0044] (2) The saturated autoclaved silicate functional aggregate has an internal curing effect. The water stored inside it is released during the hardening process of concrete, which can promote the early hydration of fly ash and mineral powder, making the 7-day and 28-day compressive strength of concrete 15-30% higher than that of ordinary concrete. At the same time, it improves the early strength of concrete and solves the problem that the addition of traditional internal curing materials reduces the strength of concrete.

[0045] (3) Autoclaved silicate functional aggregate is a spherical aggregate with a particle shape coefficient of less than 1.1, which can significantly improve the slump of concrete, improve pumping performance, and facilitate construction.

[0046] (4) Autoclaved silicate functional fine aggregate sand can improve the gradation of fine aggregates. The fineness modulus of natural yellow sand is often less than 1.4, which is too small for construction sand. Adding autoclaved silicate functional fine aggregate sand can increase the fineness modulus to 2.5, reaching the standard of medium sand and realizing the gradation control function.

[0047] (5) Using solid waste to prepare autoclaved silicate functional aggregates and using a large amount of fly ash and mineral powder as cementing materials can make full use of solid waste and realize a green and low-carbon concrete preparation method. Attached Figure Description

[0048] Figure 1 This is a schematic diagram illustrating the implementation process of the present invention for non-shrink, crack-resistant low-carbon concrete used in rigid waterproofing. Detailed Implementation

[0049] Since commercially available fly ash and mineral powder have large particle sizes, this invention uses fly ash and mineral powder that have been ball-milled and have an average fineness greater than 400 mesh. Other raw materials are all commercially available.

[0050] Autoclaved silicate functional aggregates have an internal curing effect. Therefore, the effective water-cement ratio of the non-shrink, crack-resistant, and energy-saving concrete described in this invention should be the ratio of the total mass of concrete mixing water plus the water stored inside the autoclaved silicate functional aggregates to the mass of the cementitious materials.

[0051] The concrete preparation method of this invention is as follows:

[0052] Step 1: 24 hours before mixing concrete, weigh autoclaved silicate functional aggregates according to the designed mix proportions, so that they can fully absorb water, reach saturated water absorption rate, and be in a saturated state.

[0053] Step 2: Weigh out crushed stone, autoclaved silicate functional aggregate and yellow sand in sequence, mix them and stir for 30 seconds; then weigh out fly ash and mineral powder and add them to the above mixture, continue stirring for 2 minutes to obtain the mixture.

[0054] Step 3: Mix the above mixture with cement, water, polycarboxylate superplasticizer and expansion agent, stir for 2 minutes to obtain the non-shrink crack-resistant low-carbon concrete of the present invention.

[0055] The implementation process for low-carbon, non-shrink, and crack-free concrete is as follows: Figure 1 .

[0056] This invention relates to rigid, waterproof, non-shrink, crack-resistant low-carbon concrete, which comprises the following components in parts by weight:

[0057] Cementitious materials: 400-500 parts; natural coarse aggregate: 100-1000 parts; artificial coarse aggregate: 60-900 parts; natural fine aggregate: 300-500 parts; artificial fine aggregate: 60-200 parts; water: 120-170 parts; water-reducing agent: 2-14 parts; expanding agent: 30-40 parts; wherein, the cementitious materials include the following components by weight: cement: 160-380 parts; fly ash: 40- 200 parts; mineral powder: 40-100 parts; preferred cement: 310-370 parts; fly ash: 40-70 parts; mineral powder: 40-70 parts; natural coarse aggregate: 780-950 parts; artificial coarse aggregate: 60-220 parts; natural fine aggregate: 450-470 parts; artificial fine aggregate: 160-190 parts; water: 130-140 parts; water-reducing agent: 3-4 parts; expansion agent: 35-38 parts.

[0058] Artificial coarse aggregate or artificial fine aggregate with a particle shape coefficient of less than 1.1 can significantly improve the slump of concrete, enhance pumpability, and facilitate construction.

[0059] The artificial coarse aggregate in this invention is autoclaved silicate functional coarse aggregate, and the artificial fine aggregate is autoclaved silicate functional fine aggregate sand. The autoclaved silicate functional coarse aggregate and autoclaved silicate functional fine aggregate sand are produced by hydrothermal synthesis method, with a synthesis pressure greater than or equal to 1 MPa, and its 24-hour saturated water absorption rate is 10% to 30%.

[0060] In this invention, the total volume of coarse aggregate in concrete accounts for 40% to 50% of the total volume, and the ratio of the volume of artificial coarse aggregate to the total volume of coarse aggregate is 10% to 90%, wherein the total volume of coarse aggregate is the sum of the volumes of natural coarse aggregate and artificial coarse aggregate; while the ratio of the volume of artificial fine aggregate to the total volume of fine aggregate is 10% to 40%, wherein the total volume of fine aggregate is the sum of the volumes of natural fine aggregate and artificial fine aggregate; in this application, the particle size of artificial or natural coarse aggregate is 5mm to 20mm, and the particle size of artificial fine aggregate is 2mm to 4mm; and the apparent density of artificial coarse aggregate or artificial fine aggregate is 1550kg / m³. 3 ~2150kg / m 3 .

[0061] The mass ratio of water to cementitious material is 30% to 35%, and the mass ratio of expansion agent to cementitious material is 6% to 12%. The expansion agent is one or more of magnesium oxide, calcium oxide, calcium sulfoaluminate gypsum type, and alum stone gypsum type expansion agents.

[0062] The following description elaborates on different embodiments:

[0063] Example 1

[0064] In this embodiment, autoclaved silicate functional aggregates as shown in Table 1 and mix design schemes as shown in Table 2 are selected to prepare concrete with a strength grade of C30.

[0065] Table 1: Physical properties of autoclaved silicate functional aggregates

[0066] Water absorption rate % <![CDATA[Dry density kg / m 3 > Cylinder compressive strength MPa 10.3 1889 19.1

[0067] Table 2: Mix Design Scheme

[0068]

[0069] The concrete mix design derived from the above scheme is shown in Table 3:

[0070] Table 3: Final mix proportions of concrete (kg / m³) 3 )

[0071]

[0072] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 4:

[0073] Table 4: Performance Comparison of Example 1 and Corresponding Ordinary Concrete

[0074]

[0075]

[0076] Example 2

[0077] In this embodiment, autoclaved silicate functional aggregates as shown in Table 5 and mix design schemes as shown in Table 6 are selected to prepare concrete with a strength grade of C40.

[0078] Table 5: Physical Properties of Autoclaved Silicate Functional Aggregates

[0079] Water absorption rate % <![CDATA[Dry density kg / m 3 > Cylinder compressive strength MPa 19.0 1816 18.2

[0080] Table 6: Mix Proportion Design Scheme

[0081]

[0082] The concrete mix design derived from the above scheme is shown in Table 7:

[0083] Table 7: Final mix proportions of concrete (kg / m3)

[0084]

[0085] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 8:

[0086] Table 8: Performance Comparison of Examples and Corresponding Ordinary Concrete

[0087]

[0088] Example 3

[0089] In this embodiment, autoclaved silicate functional aggregates as shown in Table 9 and mix design schemes as shown in Table 10 are selected to prepare concrete with a strength grade of C50.

[0090] Table 9: Physical Properties of Autoclaved Silicate Functional Aggregates

[0091] Water absorption rate % <![CDATA[Dry density kg / m 3 > Cylinder compressive strength MPa 24.7 1789 17.1

[0092] Table 10 Mix Design Scheme

[0093]

[0094] The concrete mix design derived from the above scheme is shown in Table 11:

[0095] Table 11: Final mix proportions of concrete (kg / m3)

[0096]

[0097] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 12:

[0098] Table 12: Performance Comparison of Examples and Corresponding Ordinary Concrete

[0099]

[0100] Example 4

[0101] In this embodiment, autoclaved silicate functional aggregates as shown in Table 13 and mix design schemes as shown in Table 14 are selected to prepare concrete with a strength grade of C50.

[0102] Table 13 Physical properties of autoclaved silicate functional aggregates

[0103] Water absorption rate % <![CDATA[Density kg / m 3 > Cylinder compressive strength MPa 24.7 1789 17.1

[0104] Table 14: Mix Proportion Design Scheme

[0105]

[0106] The concrete mix design derived from the above scheme is shown in Table 15:

[0107] Table 15: Final mix proportions of concrete (kg / m3)

[0108]

[0109] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 16:

[0110] Table 16: Performance Comparison of Examples and Corresponding Ordinary Concrete

[0111]

[0112] Example 5

[0113] In this embodiment, autoclaved silicate functional aggregates as shown in Table 17 and mix design schemes as shown in Table 18 are selected to prepare concrete with a strength grade of C60.

[0114] Table 17: Physical Properties of Autoclaved Silicate Functional Aggregates

[0115] Water absorption rate % <![CDATA[Density kg / m 3 > Cylinder compressive strength MPa 29.1 1695 18.6

[0116] Table 18: Mix Proportion Design Scheme

[0117]

[0118] The concrete mix design derived from the above scheme is shown in Table 19:

[0119] Table 19: Final mix proportions of concrete (kg / m3)

[0120]

[0121] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 20:

[0122] Table 20: Performance Comparison of Examples and Corresponding Ordinary Concrete

[0123]

[0124] Example 6

[0125] In this embodiment, autoclaved silicate functional aggregates as shown in Table 21 and mix design schemes as shown in Table 22 are selected to prepare concrete with a strength grade of C70.

[0126] Table 21 Physical properties of autoclaved silicate functional aggregates

[0127] Water absorption rate % <![CDATA[Dry density kg / m 3 > Cylinder compressive strength MPa 30.0 1585 20.6

[0128] Table 22 Mix Design Scheme

[0129]

[0130] The concrete mix design derived from the above scheme is shown in Table 23:

[0131] Table 23: Final mix proportions of concrete (kg / m3)

[0132]

[0133] The performance comparison results between ordinary concrete and concrete in this embodiment are shown in Table 24:

[0134] Table 24: Performance Comparison of Examples and Corresponding Ordinary Concrete

[0135]

[0136] All embodiments prepared according to the method of the present invention achieved a permeability rating of P12, meeting the requirements for rigid waterproofing. The 28-day compressive strength of all embodiments prepared according to the method of the present invention was significantly higher than that of ordinary concrete of the same strength grade, the slump of all embodiments was significantly higher than that of ordinary concrete of the same strength grade, and the free expansion rate of all embodiments was significantly higher than that of ordinary concrete of the same strength grade.

[0137] In summary, compared with the prior art, the non-shrinkage, crack-resistant low-carbon concrete for rigid waterproofing of this invention has the following advantages:

[0138] (1) By utilizing the internal curing effect of saturated autoclaved silicate functional aggregates and the effect of mineral admixtures to prolong the hydration time of concrete, the shrinkage and cracking of concrete can be greatly reduced.

[0139] (2) The internal curing effect of saturated autoclaved silicate functional aggregates promotes the early hydration of fly ash and mineral powder, making the compressive strength and early strength of concrete higher than that of ordinary concrete, thus solving the problem that the addition of traditional internal curing materials reduces the strength of concrete.

[0140] (3) Autoclaved silicate functional aggregates can significantly improve the slump of concrete, thereby improving the pumpability of concrete and facilitating construction.

[0141] (4) Autoclaved silicate functional fine aggregate sand can improve the gradation of fine aggregate and solve the problem of the small fineness modulus of natural yellow sand.

[0142] (5) Using solid waste to prepare autoclaved silicate functional aggregates and using a large amount of fly ash and mineral powder as cementing materials can make full use of solid waste and realize a green and low-carbon concrete preparation method.

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A non-shrink, crack-resistant low-carbon concrete for rigid waterproofing, characterized in that, Includes the following components in parts by weight: Cementitious material: 400-500 parts; Natural coarse aggregate: 100-1000 parts; Artificial coarse aggregate: 60-900 parts; Natural fine aggregate: 300-500 parts; Artificial fine aggregate: 60-200 parts; Water: 120-170 parts; Water-reducing agent: 2-14 parts; Expanding agent: 30-40 parts; The artificial coarse aggregate is autoclaved silicate functional coarse aggregate, and the artificial fine aggregate is autoclaved silicate functional fine aggregate sand. The 24-hour saturated water absorption rate of the artificial coarse aggregate and the artificial fine aggregate is 10% to 30%. The artificial coarse aggregate and artificial fine aggregate are at saturated water absorption rate.

2. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The cementitious material comprises the following components in parts by weight: Cement: 160-380 parts; Fly ash: 40-200 parts; Mineral powder: 40-100 parts.

3. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 2, characterized in that: Includes the following components in parts by weight: Cement: 310-370 parts; Fly ash: 40-70 parts; Mineral powder: 40-70 parts; Natural coarse aggregate: 780–950 parts; Artificial coarse aggregate: 60-220 parts; Natural fine aggregate: 450-470 parts; Artificial fine aggregate: 160-190 parts; Water: 130-140 parts; Water-reducing agent: 3-4 parts; Expanding agent: 35-38 parts.

4. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The total volume of coarse aggregate in concrete accounts for 40% to 50% of the total volume, and the ratio of the volume of artificial coarse aggregate to the total volume of coarse aggregate is 10% to 90%. The total volume of coarse aggregate is the sum of the volumes of natural coarse aggregate and artificial coarse aggregate.

5. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The ratio of the volume of the artificial fine aggregate to the total volume of the fine aggregate is 10% to 40%, and the total volume of the fine aggregate is the sum of the volumes of the natural fine aggregate and the artificial fine aggregate.

6. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The mass ratio of water to the cementitious material is 30% to 35%.

7. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The mass ratio of the expanding agent to the cementitious material is 6% to 12%.

8. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The particle size of the artificial coarse aggregate or the natural coarse aggregate is 5mm to 20mm, and the particle size of the artificial fine aggregate is 2mm to 4mm.

9. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The apparent density of the artificial coarse aggregate or the artificial fine aggregate is 1550 kg / m³. 3 ~2150kg / m 3 .

10. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 2, characterized in that: The mass of the cementitious material is 450 kg / m³. 3 The mass of the cement is 180 kg / m³. 3 ~360kg / m 3 The mass of the fly ash is greater than or equal to 45 kg / m³. 3 The mass of the mineral powder is greater than or equal to 45 kg / m³. 3 .

11. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 4, characterized in that: The autoclaved silicate functional coarse aggregate and the autoclaved silicate functional fine aggregate sand are produced by hydrothermal synthesis, with a synthesis pressure greater than or equal to 1 MPa.

12. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The expanding agent is one or more of magnesium oxide, calcium oxide, calcium sulfoaluminate gypsum type, and alum stone gypsum type expanding agents.

13. The non-shrink, crack-resistant low-carbon concrete for rigid waterproofing as described in claim 1, characterized in that: The particle shape coefficient of the artificial coarse aggregate or the artificial fine aggregate is less than 1.1.

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