Early-strength concrete pavement rapid repairing material and preparation method thereof

Abstract

The invention relates to the technical field of building admixtures, in particular to an early-strength concrete pavement rapid repairing material and a preparation method thereof. The material is composed of quick-hardening sulphoaluminate cement, modified Portland cement, sand, a polycarboxylate superplasticizer, an expanding agent, water and sodium gluconate. The preparation method comprises the following steps: mixing and stirring the raw materials, adding water, stirring, molding and the like. Through specific raw material combination and process, the repairing material has the advantages of good self-leveling property, high early strength (1.5 h compressive strength reaches 30 MPa or above, and 1d compressive strength reaches 40 MPa or above), high adhesion, adjustable setting time, no shrinkage and the like, is convenient to construct, is suitable for emergency repair projects such as roads, military projects, airport roads and the like, and has wide application prospects. The problems that a traditional repairing material is tedious in construction and slow in hardening, influences traffic and the like are effectively solved, and important practical value and innovative significance are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of building admixtures, and in particular to an early-strength concrete pavement rapid repair material and a preparation method thereof. Background Art

[0002] In today's society, transportation infrastructure construction is booming, and cement concrete pavement is widely used in many fields such as highways and urban roads. However, with the rapid growth of traffic flow and the continuous increase in vehicle loads, cement concrete pavement is facing severe tests.

[0003] The sharp increase in traffic volume has caused most cement concrete pavements to suffer serious damage in a short period of time, and the initial manifestations are often concentrated in local areas of the pavement. For example, cracks may be caused by factors such as temperature changes, uneven foundation settlement or concrete shrinkage. If small cracks are not handled in time, they will gradually expand and extend under repeated vehicle rolling and water erosion, destroying the integrity of the pavement structure; local damage to concrete near joints is also very common. Due to construction technology, material performance differences and long-term stress, concrete is prone to peeling and fragmentation at joints, affecting driving comfort and weakening the bearing capacity of the pavement; damage to pavement expansion joints will lead to uncoordinated expansion and contraction between pavement panels, which will in turn cause deformation and damage to adjacent panels; corner fractures usually occur at the edge or corner of the pavement, where the stress is more complex. Under the impact of vehicle impact and lateral stress, concrete is prone to fracture; surface shedding is due to the long-term wear, freeze-thaw cycles and chemical erosion of the concrete surface, which reduces the strength of the surface concrete and eventually falls off to form potholes.

[0004] The emergence of these local diseases has caused many newly built cement concrete pavements to be scarred long before they reach the design service life stipulated by the state. These seemingly small-scale local diseases actually hide huge hidden dangers. If they are not repaired in a timely and effective manner, the diseases will be further aggravated at an alarming rate. For example, the expansion of cracks may cause the entire pavement slab to break, joint damage will cause the pavement structure to lose stability, and edge fractures and surface shedding will accelerate the process of pavement damage, ultimately causing large-scale damage to the pavement, which will not only seriously affect traffic flow and driving safety, but will also greatly increase the cost of pavement repair, bringing a heavy burden to the social economy.

[0005] At present, most of the research and application results in the field of cement concrete pavement repair at home and abroad still use traditional ordinary concrete repair technology. Traditional cement-based material repair technology has exposed many problems in practical applications. Its construction process is complicated and cumbersome, involving multiple construction links and complex operation processes, and has high technical requirements for construction personnel. The slightest carelessness may affect the repair effect. Moreover, poor adhesion at the repair interface is one of its most prominent problems. It is difficult to form a good bond between the repair material and the original pavement concrete, which leads to stress concentration at the interface of the repaired pavement when it is stressed, causing the repaired part to fail prematurely, and the overall repair effect is extremely unsatisfactory. If the whole plate repair technology is used, although some problems can be fundamentally solved, this method not only takes a long time to repair and seriously interferes with normal traffic order, but also requires huge human, material and financial resources, high costs, and low economic feasibility.

[0006] In response to the thorny problems of traditional repair methods such as being time-consuming and labor-intensive, having a long curing period, and seriously affecting traffic, many researchers have turned their attention to the research and development of rapid concrete repair materials, trying to break through the bottleneck of traditional repair technology through innovative materials.

[0007] Patent CN 103360001 A discloses a fast-hardening early-strength concrete for full-thickness repair of cement concrete pavement. This repair material has the advantages of fast repair speed and high early strength to a certain extent. Its early strength 24h compressive strength can reach more than 30MPa. However, from the actual demand for rapid restoration of traffic, it still does not meet the stringent requirement of opening traffic within 2 hours, and cannot meet the urgent expectations of modern traffic for efficient repairs.

[0008] Patent CN 112777983 A discloses a concrete rapid repair material and its preparation method, which has the characteristics of fast setting time, high bonding strength, relatively stable performance and low cost. However, its 3d compressive strength can only reach more than 30MPa, and its early strength growth is slow, which is far from meeting the urgent need to open traffic within 2 hours, and it seems incapable of responding to emergency repair projects.

[0009] Patent CN 111747713 A discloses an early-strength self-leveling concrete pavement rapid repair material and its preparation method. The material has excellent performance in strength development, with a 2h compressive strength of more than 30MPa and a 1d compressive strength of more than 30MPa. Unfortunately, its raw material components are complex and diverse, and the admixture is in liquid form. Special containers and conditions are required during transportation and storage, and it involves the addition of coarse aggregate, which makes the construction operation cumbersome and complicated, not only increasing the construction difficulty and cost, but also inconvenient for long-distance transportation, and it is difficult to meet the requirements of emergency repair projects and other scenes with extremely high requirements for material transportation convenience and construction efficiency. Summary of the invention

[0010] The present invention aims to overcome the problem that the existing concrete rapid repair materials are slow to meet the compressive strength requirements. The present invention provides an early-strength concrete pavement rapid repair material, comprising the following raw materials: fast-hardening sulphoaluminate cement, modified silicate cement, sand, polycarboxylate water reducer, expansion agent, water and sodium gluconate; Wherein, the mass ratio of the rapid hardening sulphoaluminate cement, the modified silicate cement and the sodium gluconate is 50-70:30-50:0-0.4.

[0011] On the basis of the above technical scheme, the following raw materials are further included in weight: 50-70 parts of fast-hardening sulphoaluminate cement, 30-50 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 1 part of expansion agent, 23 parts of water and 0-0.4 parts of sodium gluconate. Preferably, the sodium gluconate is 0.2-0.4 parts. Adding a small amount of sodium gluconate can rapidly improve the compressive strength of the rapid repair material in the early stage, and at the same time improve the initial setting and final setting time of cement, so that it has better operability in construction, and at the same time helps to maintain the flow properties of the material to a certain extent, so that the material can better self-level during the construction process, fill the small gaps and uneven places on the road surface, thereby improving the density and integrity of the repaired road surface, so that it can adapt to different construction conditions and road conditions, and improve the comprehensive performance of the repair material, so that it has achieved significant improvements and improvements in mechanical properties, working performance, crack resistance, etc., and effectively solves various problems existing in existing concrete pavement repair technology.

[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 modified silicate cement comprises the following raw materials calculated by weight: 30-60 parts of tricalcium silicate, 15-40 parts of dicalcium silicate, 7-15 parts of tricalcium aluminate, 10-20 parts of tetracalcium aluminoferrite; And, mixed materials: 20-70 parts of granulated blast furnace slag, 20-50 parts of pozzolanic mixed materials, 5-10 parts of silica fume, and 3-5 parts of gypsum; The above raw materials are fully stirred until they are uniform to obtain the modified silicate cement.

[0014] 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.

[0015] On the basis of the above technical solution, further, the water reducer is Sika 540P produced by Shanghai Chenqi Chemical Technology Co., Ltd.

[0016] On the basis of the above technical solution, further, the expansion agent is a concrete type II expansion agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd., which is a light yellow powder.

[0017] The present invention also provides a method for preparing any of the above-mentioned early-strength concrete pavement rapid repair materials, comprising the following steps: Take quick-hardening sulphoaluminate cement, silicate cement, sand, polycarboxylate water reducer, expansion agent, sodium gluconate, and water; Except for the mixing water, pour all other materials into the blender and mix evenly for about 30 seconds. When the mixing is finished, pour the mixing water in and stir; After the stirring is completed, the material is molded to obtain the early-strength concrete pavement rapid repair material.

[0018] The technical solution of the present invention has the following principles and beneficial effects: The early-strength concrete pavement rapid repair material provided by the present invention is formulated with rapid-hardening sulphoaluminate cement and modified silicate cement in a specific mass ratio and the synergistic effect of other additives, thereby achieving a balance between early strength and late strength development, ensuring that the repair material has good strength development both in the early and late stages, and can not only achieve rapid pavement repair, with a 1.5h compressive strength of more than 30MPa and a 1d compressive strength of more than 40MPa, but also improve the durability of the repaired pavement.

[0019] The early-strength concrete pavement rapid repair material provided by the present invention has achieved significant improvements and enhancements in many aspects such as mechanical properties, working performance, crack resistance and construction convenience, and the various properties are coordinated with each other to form an organic whole. It can effectively solve various problems existing in existing concrete pavement repair technologies, such as insufficient early strength of traditional repair materials, uncontrollable setting time, complex construction, etc., and has high practical value and innovation. DETAILED DESCRIPTION

[0020] 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.

[0021] The present invention provides the following embodiments: Example 1 Material preparation: Accurately weigh 50 parts of rapid-hardening sulphoaluminate cement, 50 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0 parts of sodium gluconate.

[0022] Among them, the rapid hardening sulphoaluminate cement is grade 42.5, and its preparation process 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.

[0023] 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.

[0024] 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 to 450 m² / kg, thus obtaining the fast-hardening sulphoaluminate cement that meets the requirements.

[0025] Among them, the components and preparation method of modified silicate cement are: Modified silicate cement of grade 42.5 is obtained by mixing and stirring silicate cement clinker (45 parts of tricalcium silicate (C3S), 25 parts of dicalcium silicate (C2S), 10 parts of tricalcium aluminate (C3A), 15 parts of tetracalcium aluminoferrite (C4AF)), mixed materials (40 parts of granulated blast furnace slag, 30 parts of pozzolanic mixed materials, 8 parts of silica fume), and 4 parts of gypsum (CaSO4・2H2O) at room temperature.

[0026] Among them, the sand used is machine-made sand with a fineness modulus of 2.6, a bulk density of 1470kg / m³, and a crushing index value of 21.

[0027] The water reducer is Sika 540P produced by Shanghai Chenqi Chemical Technology Co., Ltd., which is a white to light yellow powder.

[0028] The expansive agent is concrete type II expansive agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd., which is a light yellow powder.

[0029] Mixing water meets the standards of JGJ 63~2006 "Standard for Water for Concrete".

[0030] The preparation process of the early-strength concrete pavement rapid repair material is as follows: Pour all the weighed fast-hardening sulphoaluminate cement, silicate cement, sand, polycarboxylate water-reducing agent, expansion agent and sodium gluconate (0 part of sodium gluconate in this embodiment) into a mixer that complies with the provisions of GB 10171, and start the mixer and stir for about 30 seconds to fully mix the solid materials.

[0031] After the mixing is completed, slowly pour the 23 parts of mixing water prepared in advance into the mixer and continue mixing to ensure that the material and water are fully mixed to form a uniform early-strength concrete pavement rapid repair material.

[0032] Example 2 Material preparation: Weigh 60 parts of rapid-hardening sulphoaluminate cement, 40 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0 parts of sodium gluconate.

[0033] The remaining conditions and preparation process are the same as those in Example 1, and an early-strength concrete pavement rapid repair material is obtained.

[0034] Example 3 Material preparation: Weigh 70 parts of rapid-hardening sulphoaluminate cement, 30 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0 parts of sodium gluconate.

[0035] The remaining conditions and preparation process are the same as those in Example 1, and an early-strength concrete pavement rapid repair material is obtained.

[0036] Example 4 Material preparation: Weigh 70 parts of rapid-hardening sulphoaluminate cement, 30 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0.2 parts of sodium gluconate.

[0037] The remaining conditions and preparation process are the same as those in Example 1, and an early-strength concrete pavement rapid repair material is obtained.

[0038] Example 5 Material preparation: Weigh 70 parts of rapid-hardening sulphoaluminate cement, 30 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0.3 parts of sodium gluconate.

[0039] The remaining conditions and preparation process are the same as those in Example 1, and an early-strength concrete pavement rapid repair material is obtained.

[0040] Example 6 Material preparation: Weigh 70 parts of rapid-hardening sulphoaluminate cement, 30 parts of modified silicate cement, 100 parts of sand, 0.39 parts of polycarboxylate water reducer, 23 parts of water, 1 part of expansion agent, and 0.4 parts of sodium gluconate.

[0041] The remaining conditions and preparation process are the same as those in Example 1, and an early-strength concrete pavement rapid repair material is obtained.

[0042] Comparative Example 1 The difference from Example 1 is that 30 parts of rapid-hardening sulphoaluminate cement and 70 parts of modified silicate cement are used; the other conditions and preparation process are the same as those in Example 1.

[0043] Comparative Example 2 The difference from Example 1 is that the rapid hardening sulphoaluminate cement is replaced by ordinary cement (model P.O42.5).

[0044] Comparative Example 3 The difference from Example 1 is that the modified silicate cement is replaced by ordinary silicate cement, and compared with the modified silicate cement provided in the embodiment of the present invention, the clinker only uses tricalcium silicate, and other conditions remain the same.

[0045] The performance tests were carried out on the materials prepared in the above embodiments and comparative proportions, and the test method was GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete"; the test environment temperature was 24°C; the test results are shown in Table 1.

[0046] Table 1 sample Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 1.5h compressive strength / MPa 26.8 28.6 28.9 30.5 30 30.8 23 invalid 21 1d compressive strength / MPa 42.4 43 45.6 41.5 42 45 38 30 36 Initial fluidity / mm 300 290 285 295 285 280 290 300 300 30min fluidity / mm 280 270 265 275 265 260 270 280 280 Initial setting time / min 9 7 5 12 25 42 30 720 13 Final setting time / minFinal settingFinal setting time / min 12 9 7 15 30 53 60 1200 18 From Table 1, it can be found that the early-strength concrete pavement rapid repair materials obtained in Examples 4, 5, and 6 have the best comprehensive performance, with a 1.5h compressive strength of more than 30MPa and a 1d compressive strength of more than 40MPa. The setting time and fluidity can meet the 1.5h open road traffic performance index requirements, and can also well meet the special needs of emergency engineering rapid setting and early strength. The changes in the material composition in different embodiments, especially the adjustment of the amount of sodium gluconate, have different degrees of influence on the performance of the repair material, providing a basis for further optimizing the material formula.

[0047] 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. An early-strength concrete pavement rapid repair material, characterized in that: The raw materials include: rapid hardening sulphoaluminate cement, modified silicate cement, sand, polycarboxylate water reducer, expansion agent, water and sodium gluconate; Wherein, the mass ratio of the rapid hardening sulphoaluminate cement, the modified silicate cement and the sodium gluconate is 50-70:30-50:0-0.

4.

2. The early-strength concrete pavement rapid repair material according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 50-70 parts of rapid hardening sulphoaluminate cement, 30-50 parts of modified silicate cement, 100-110 parts of sand, 0.39-0.45 parts of polycarboxylic acid water reducer, 1-3 parts of expansion agent, 21-23 parts of water and 0-0.4 parts of sodium gluconate.

3. The early-strength concrete pavement rapid 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 early-strength concrete pavement rapid repair material according to claim 1, characterized in that: The modified silicate cement comprises the following raw materials calculated by weight: 30-60 parts of tricalcium silicate, 15-40 parts of dicalcium silicate, 7-15 parts of tricalcium aluminate, 10-20 parts of tetracalcium aluminoferrite; And, mixed materials: 20-70 parts of granulated blast furnace slag, 20-50 parts of pozzolanic mixed materials, 5-10 parts of silica fume, and 3-5 parts of gypsum; The above raw materials are fully stirred until uniform to obtain the modified silicate cement.

5. The early-strength concrete pavement rapid 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.

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

7. The early strength concrete pavement rapid repair material according to claim 1, characterized in that: The expansive agent is a concrete type II expansive agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd., which is a light yellow powder.

8. A method for preparing the early-strength concrete pavement rapid repair material according to any one of claims 1 to 7, characterized in that: The following steps are involved: Take quick-hardening sulphoaluminate cement, silicate cement, sand, polycarboxylate water reducer, expansion agent, sodium gluconate, and water; Except for the mixing water, pour all other materials into the blender and mix evenly. When the mixing is finished, pour the mixing water in and stir; After the stirring is completed, the material is molded to obtain the early-strength concrete pavement rapid repair material.