Quick-setting early-strength low-temperature applicable concrete pavement patching material and preparation method thereof

Abstract

The invention relates to the technical field of building admixtures, in particular to a quick-setting early-strength low-temperature applicable concrete pavement patching material, which is prepared from the following raw materials in parts by weight: quick-hardening sulphoaluminate cement, NaNO, a crystal nucleus early strength agent, sand, a polycarboxylate superplasticizer, an expanding agent and water. The quick-hardening sulphoaluminate cement is prepared from CaO, AlO and CaSOin a specific proportion, the sand is preferably machine-made sand with specific fineness modulus, bulk density and crushing index value, and all the components play an important role. The preparation method comprises the steps of material preparation, stirring, forming, curing and the like, and each step has specific process conditions. The repairing material has the advantages that the raw materials are convenient to transport, and construction is convenient; the materials are not required to be heated at-17 DEG C to-12 DEG C, and water and equipment are not required to be mixed; the compressive strength within 2 hours reaches 30 MPa, and the open traffic requirement is met; the transportation is convenient in emergency repair engineering, the repair time can be shortened, and the problem of pavement repair in cold regions is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of building admixtures, and in particular to a quick-setting, early-strength, low-temperature applicable concrete pavement repairing material and a preparation method thereof. Background Art

[0002] In today's society, my country's economy is showing a trend of rapid growth, and all related industries have achieved rapid development. At the same time, with the vigorous promotion of urban and rural construction and the continuous increase in the number of cars, my country's demand for road transportation has reached an unprecedented level. As an important support for economic development, road transportation not only requires large-scale construction of new roads to expand the transportation network, but also requires great attention to the maintenance and repair of the built roads to ensure that the roads always maintain a good operating state and meet the growing traffic flow demand.

[0003] Cement concrete pavements in cold regions face extremely severe challenges. The environment in these regions is usually very harsh, with factors such as freezing, scorching heat, and a large number of vehicle loads intertwined, causing serious damage to the road surface. In winter, the low temperature environment causes the road surface to freeze and thaw repeatedly, and the internal structure of the concrete is damaged due to the expansion of water freezing, which in turn causes cracks, peeling and other diseases; the high temperature in summer may cause the concrete to lose water too quickly and its strength to decrease, aggravating the aging of the road surface; and the load generated by the frequent driving of a large number of vehicles further accelerates the wear and damage of the road surface. Such harsh environmental conditions have greatly shortened the service life of cement concrete pavements in cold regions, and the damage is extremely serious.

[0004] In the field of urban and rural road construction, road damage seriously affects the smoothness and safety of traffic. Timely and effective repair work is crucial to ensure the normal operation of residents' daily travel and economic activities. In emergency projects, once a road is damaged, it must be repaired quickly to ensure the rapid transportation of personnel, equipment and materials to meet urgent needs. However, the unique climatic conditions in cold regions have brought great difficulties to road repair work.

[0005] There are many limitations to the use of traditional repair materials in cold regions. From the construction perspective, the operation is cumbersome and often requires complex processing such as heating the materials, mixing water and equipment, which not only increases the construction cost, but also consumes a lot of time, seriously affecting the construction efficiency. In terms of performance, in addition to meeting basic repair functions such as filling potholes and restoring the flatness of the road surface, it must also have good frost resistance to resist the damage of the cold environment to the repair materials. However, it is difficult for traditional repair materials to meet these requirements at the same time, which greatly reduces their applicability in cold regions.

[0006] In response to the above problems, many researchers have been committed to the research and development of negative temperature repair materials, trying to solve the problems of cumbersome construction and long construction time of traditional repair materials. For example, patent CN107459327A discloses a concrete rapid repair material suitable for construction in low temperature or negative temperature environment. The material has certain advantages in low temperature formability, hardening speed and setting time control, but its early strength 2h compressive strength does not reach more than 30MPa, which cannot meet the strict requirements of 2h open traffic. In practical applications, traffic may be blocked for a long time, causing many inconveniences to society and the economy.

[0007] Patent CN111995337A discloses a low-negative-temperature cement-based rapid repair material, which has an applicable temperature range of -40°C to 0°C, has a certain repair ability in extremely cold areas, and has high early strength, and can meet the needs of opening traffic in a short time. However, the material involves the use of coarse aggregate. In emergency repair projects, the presence of coarse aggregate increases the weight of the material, making it inconvenient to transfer quickly, seriously affecting the efficiency of emergency repairs, and failing to meet the requirements of flexibility and timeliness of emergency operations.

[0008] Patent CN114276094A discloses a rapid repair material for engineering use in negative temperature environments and its preparation method. The material can reach a compressive strength of more than 20MPa in 3 hours at an ambient temperature of -10°C. Although it can meet the basic strength requirements of emergency repair projects to a certain extent, its strength growth rate is still not ideal for road traffic, and it is impossible to achieve rapid opening of traffic, resulting in traffic congestion and delays, bringing inconvenience to social production and people's lives.

[0009] In summary, the repair materials in the prior art all have defects to varying degrees, and it is difficult to fully meet the strict requirements for rapid setting and early strength, low temperature applicability, construction convenience and high strength of concrete pavement repair materials in cold areas, especially in emergency repair projects. Summary of the invention

[0010] The present invention aims to overcome the problem that the existing concrete quick repair material is slow to meet the compressive strength requirements. The present invention provides a quick-setting, early-strengthening, low-temperature applicable concrete pavement repair material, comprising the following raw materials: quick-hardening sulphoaluminate cement, NaNO2, crystal nucleus early strength agent, sand, polycarboxylate water reducer, expansion agent and water; The mass ratio of the fast-hardening sulphoaluminate cement, NaNO2 and early strength agent is 100:5:0.5-1.8.

[0011] On the basis of the above technical scheme, the following raw materials are further included in weight parts: 90-100 parts of fast-hardening sulphoaluminate cement, 5 parts of NaNO2, 0.5-1.5 parts of crystal nucleus early strength agent, 100-110 parts of sand, 0.9-1.0 parts of polycarboxylic acid water reducer, 1 part of expansion agent and 21-22 parts of water.

[0012] On the basis of the above technical solution, further, the rapid hardening sulphoaluminate cement is prepared from 40-50 parts of CaO, 30-40 parts of Al2O3 and 10-20 parts of CaSO4 according to the following method: Put the raw materials into the mixing equipment according to the calculated ratio and mix them evenly; The calcination is carried out in a rotary kiln at a temperature between 1250 and 1350°C; The calcined clinker needs to be cooled and ground with an appropriate amount of gypsum until the specific surface area reaches 350-450m 2 / kg, the fast-hardening sulphoaluminate cement is obtained.

[0013] On the basis of the above technical solution, further, the crystal nucleus early strength agent is composed of a mixture of 20 to 40 parts of water-soluble polycarboxylic acid sodium salt and 60 to 80 parts of calcium silicate.

[0014] On the basis of the above technical solution, further, it also includes an amorphous core early strength agent, wherein the amorphous core early strength agent is lithium carbonate.

[0015] On the basis of the above technical solution, further, the ratio of NaNO2, crystal nucleus early strength agent and amorphous core early strength agent is 5:0.5-1:0.1-0.3. The use of NaNO2, special crystal nucleus early strength agent and lithium carbonate in a specific ratio can further enhance the initial and long-term compressive strength in a low temperature environment.

[0016] On the basis of the above technical solution, further, the sand has a fineness modulus of 2.3-3.0 and a bulk density of 1350-1470 kg / m 3 , artificial sand with crushing index value of 21 to 25.

[0017] On the basis of the above technical solution, further, the polycarboxylate water reducer is Sika 540P produced by Shanghai Chenqi Chemical Technology Co., Ltd.

[0018] On the basis of the above technical solution, further, the expansion agent is concrete type II expansion agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd.

[0019] The present invention also provides a method for preparing any of the above-mentioned quick-setting, early-strength, low-temperature applicable concrete pavement repair materials, comprising the following steps: Weigh the raw materials according to the proportion, mix and stir the raw materials evenly; the temperature of the water used for stirring is 1°C; After stirring evenly, seal the mixture. The sealing environment temperature is -17℃~-12℃. The sealing time is such that the material temperature after stirring evenly is consistent with the sealing environment temperature. The stirring time is 1~2 min. After the sealing is completed, the material is molded to obtain the quick-setting, early-strength, low-temperature applicable concrete pavement repair material.

[0020] The technical solution of the present invention has the following principles and beneficial effects: The fast-setting, early-strength, low-temperature-applicable concrete pavement repair material provided by the present invention achieves a balance between early strength and late strength development in a low-temperature environment through the combination of fast-hardening sulphoaluminate cement and NaNO2, as well as the synergistic effect of other additives, thereby ensuring that the repair material has good strength development both in the early and late stages, and realizing rapid pavement repair in a low-temperature environment.

[0021] Preferably, NaNO2, a specific crystal nucleus early strength agent and a crystal nucleus early strength agent are used in combination to prevent the liquid phase of the concrete from freezing and, at the same time, synergize with the coagulant to allow the concrete to quickly develop early strength even at low temperatures.

[0022] The quick-setting, early-strength, low-temperature-applicable concrete pavement repair material of the present invention exhibits excellent performance in construction convenience, low-temperature applicability, strength development, and rapid emergency repair applications through the synergistic effect of various components, effectively overcomes the shortcomings of the prior art, and has broad application prospects and significant social and economic benefits. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The present invention provides the following embodiments: Example 1 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 0.5 parts of crystal core early strength agent, and 0 parts of amorphous core early strength agent.

[0025] The preparation process of rapid hardening sulphoaluminate is as follows: Ingredient calculation and mixing: According to the performance requirements of cement, the mixing ratio of CaO, Al2O3 and CaSO4 is accurately calculated. The pre-treated raw materials such as limestone, alumina and gypsum are placed in a ball mill or mixer according to the calculated ratio to ensure that the raw materials are fully and evenly mixed.

[0026] Calcination: The mixed raw materials are calcined in a rotary kiln, and the calcination temperature is controlled between 1250 and 1350°C, so that the raw materials undergo chemical reactions in a stable high-temperature environment to form the required clinker.

[0027] Cooling and grinding: The calcined clinker is cooled quickly by air or water and then ground with an appropriate amount of gypsum until the specific surface area reaches about 350-450m² / kg, thus obtaining the fast-hardening sulphoaluminate cement that meets the requirements.

[0028] Among them, the sand used is machine-made sand with a fineness modulus of 2.7, a bulk density of 1470kg / m³, and a crushing index value of 21.

[0029] The water reducer is Sika 540P produced by Shanghai Chenqi Chemical Technology Co., Ltd., which is a white to light yellow powder.

[0030] The expansive agent is concrete type II expansive agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd., which is a light yellow powder.

[0031] Mixing water meets the standards of JGJ 63~2006 "Standard for Water for Concrete".

[0032] The preparation process of quick-setting, early-strength, low-temperature applicable concrete pavement repair material is as follows: Weigh the raw materials according to the proportion, mix and stir the raw materials evenly; the temperature of the water used for stirring is 1°C; After stirring evenly, seal the mixture. The sealing environment temperature is -17°C. The sealing time is such that the material temperature after stirring evenly is consistent with the sealing environment temperature. The stirring time is 1 minute. After the sealing is completed, the material is molded to obtain the quick-setting, early-strength, low-temperature applicable concrete pavement repair material.

[0033] Example 2 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 1 part of crystal nucleus early strength agent, and 0 parts of amorphous core early strength agent.

[0034] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0035] Example 3 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 1.5 parts of crystal core early strength agent, and 0 parts of amorphous core early strength agent.

[0036] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0037] Example 4 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 1 part of crystal core early strength agent, and 0.1 part of amorphous core early strength agent.

[0038] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0039] Example 5 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 1 part of crystal core early strength agent, and 0.2 parts of amorphous core early strength agent.

[0040] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0041] Example 6 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 1 part of crystal nucleus early strength agent, and 0.3 parts of amorphous core early strength agent.

[0042] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0043] Comparative Example 1 Material preparation: 100 parts of fast-hardening sulphoaluminate cement, 100 parts of sand, 1 part of polycarboxylic acid water-reducing agent, 21 parts of water, 1 part of expansion agent, 5 parts of antifreeze agent, 0 parts of crystal core early strength agent, and 0 parts of amorphous core early strength agent.

[0044] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0045] Comparative Example 2 The difference from Example 1 is that 0.5 parts of the crystal core early strength agent is replaced by 0.5 parts of an amorphous core early strength agent, which is lithium carbonate.

[0046] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0047] Comparative Example 3 The difference from Example 1 is that the rapid-hardening sulphoaluminate cement is replaced by ordinary cement (model P.O42.5), compared with the rapid-hardening sulphoaluminate cement.

[0048] The remaining conditions and preparation process are the same as those in Example 1, and a quick-setting, early-strength, low-temperature applicable concrete pavement repair material is obtained.

[0049] Comparative Example 4 The difference from Example 1 is that no NaNO2 is added.

[0050] The materials prepared in the above embodiments and comparative proportions were subjected to performance tests according to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete"; the test environment was -17°C, and the test was performed after demolding for 2 hours. The results are shown in Table 1.

[0051] Table 1 sample Fluidity / mm Initial setting time / min 2h compressive strength / MPa 1d compressive strength / MPa 28d compressive strength / MPa Comparative Example 1 250 24 26 38 43 Comparative Example 2 250 22 29 39 42 Comparative Example 3 255 No condensation invalid invalid invalid Comparative Example 4 252 19 27 37 40 Example 1 252 23 28 39 45 Example 2 251 22 28 40 49 Example 3 254 23 29 37 47 Example 4 251 21 30 40 53 Example 5 250 22 33 42 59 Example 6 253 20 31 40 56 As can be seen from Table 1, the rapid-setting, early-strength, low-temperature applicable concrete pavement repair material obtained in Examples 4, 5, and 6 has a 2h compressive strength of more than 30 MPa, a 1d compressive strength of more than 40 MPa, and a 28d compressive strength of more than 50 MPa, and the setting time and fluidity can meet the 2h open road traffic performance index requirements, and can also meet the rapid-setting and early-strength requirements of emergency projects.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quick-setting, early-strength, low-temperature applicable concrete pavement repair material, characterized in that: The raw materials include: fast-hardening sulphoaluminate cement, NaNO2, crystal nucleus early strength agent, sand, polycarboxylate water reducer, expansion agent and water; The mass ratio of the fast-hardening sulphoaluminate cement, NaNO2 and early strength agent is 100:5:0.5-1.

8.

2. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 90-100 parts of fast-hardening sulphoaluminate cement, 5 parts of NaNO2, 0.5-1.5 parts of crystal nucleus early strength agent, 100-110 parts of sand, 0.9-1.0 parts of polycarboxylic acid water reducer, 1 part of expansion agent and 21-22 parts of water.

3. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The rapid hardening sulphoaluminate cement is prepared from 40-50 parts of CaO, 30-40 parts of Al2O3 and 10-20 parts of CaSO4 according to the following method: Put the raw materials into the mixing equipment according to the calculated ratio and mix them evenly; The calcination is carried out in a rotary kiln at a temperature between 1250 and 1350°C; The calcined clinker needs to be cooled and ground with an appropriate amount of gypsum until the specific surface area reaches 350-450m 2 / kg, the fast-hardening sulphoaluminate cement is obtained.

4. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The crystal nucleus early strength agent is composed of 20-40 parts of water-soluble polycarboxylic acid sodium salt and 60-80 parts of calcium silicate.

5. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: It also includes an amorphous core early strength agent, wherein the amorphous core early strength agent is lithium carbonate.

6. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 5, characterized in that: The ratio of NaNO2, crystal nucleus early strength agent and amorphous core early strength agent is 5:0.5-1:0.1-0.

3.

7. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The sand has a fineness modulus of 2.3 to 3.0 and a bulk density of 1350 to 1470 kg / m 3 , artificial sand with crushing index value of 21 to 25.

8. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The polycarboxylate water reducer is Sika 540P produced by Shanghai Chenqi Chemical Technology Co., Ltd.

9. The rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to claim 1, characterized in that: The expansion agent is concrete type II expansion agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd.

10. A method for preparing the rapid-setting, early-strength, low-temperature applicable concrete pavement repair material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Weigh the raw materials according to the proportion, mix and stir the raw materials evenly; the temperature of the water used for stirring is 1°C; After stirring evenly, seal the mixture. The sealing environment temperature is -17℃~-12℃. The sealing time is such that the material temperature after stirring evenly is consistent with the sealing environment temperature. The stirring time is 1~2 min. After the sealing is completed, the material is molded to obtain the quick-setting, early-strength, low-temperature applicable concrete pavement repair material.