Antifreezing and high-ductility composite, and preparation method and use thereof

Abstract

An antifreezing and high-ductility composite comprising in parts by weight: 250-330 parts Portland cement, 900-1100 parts fly ash, 400-500 parts quartz sand, 5-30 parts polyvinyl alcohol (PVA) fibre,

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of cement materials, in particular to an antifreezing and high-ductility composite, and a preparation method and use thereof. BACKGROUND ART

[0002] During bridge construction, expansion joints are set between beam ends, between the beam ends and abutments, or at hinge joint positions of a bridge to ensure safety; one of telescopic structures of the bridge is a comb plate-type telescopic structure. In the comb plate-type telescopic structure, concreting is conducted on a lower part of the comb plate or a stainless steel sliding plate, and on both sides of the comb plate. In winter, northern China generally has a low temperature of below 0°C; ordinary concrete is easy to freeze and crack due to freeze-thaw damages during cement hydration just after concreting and in daily use. There is also a close relationship between the cement hydration just after concreting and the temperature; when the air temperature is below 0°C, water for the cement hydration begins to freeze, which leads to a decrease of water for the hydration, slowing down the hydration, resulting in a slower increase in the strength. The continuous decrease in temperature causes all water for the hydration to freeze into ice cubes, the hydration is completely terminated and the strength begins to stabilize at a certain value. In addition, water frozen into ice has an increased volume, generating a reverse stress on the concrete; and the concrete, in an initial setting stage without a sufficient strength to resist the reverse stress, is prone to damage. When the temperature rises above 0°C, ice begins to melt into water with a decreased volume, which may create voids inside the concrete, reducing reliability of a concrete structure. In daily life, there is a large temperature difference between day and night in the north, and free water in the concrete freezes and melts due to the large temperature difference. When the free water in pores reaches saturation, tensile stress is generated, making the internal pores larger. At this time, external free water continuously flows into the pores, and the above reactions continue to occur, leading to continuous enlargement of the pores. Therefore, a frost resistance of a structure is related to safety, applicability and stability of the structure, and has a significant impact on the safety of the structure. Accordingly, the frost resistance of the structure should be strengthened for driving safety and to avoid maintenance that costs manpower and material resources. SUMMARY

[0003] To overcome the deficiencies of the prior art, an objective of the present disclosure is to provide an antifreezing and high-ductility composite, and a preparation method and use thereof.

[0004] To achieve the above objective, the present disclosure provides the following technical solutions.

[0005] The present disclosure provides an antifreezing and high-ductility composite, prepared by the following raw materials in parts by weight:

[0006] 250 parts to 330 parts of a Portland cement, 900 parts to 1,100 parts of fly ash, 400 parts to 500 parts of quartz sand. 5 parts to 30 parts of a polyvinyl alcohol fiber, 0.5 parts to 0.7 parts of sodium carboxymethyl cellulose, 5 parts to 6 parts of an antifreeze agent, 6 parts to 7 parts of a water reducer, 2.3 parts to 2.7 parts of an air entraining agent, 3 parts to 3.5 parts of an early strength agent, and 300 parts to 410 parts of water.

[0007] Preferably, the fly ash may have a particle size of 0.45 pm to 2 pm; and the quartz sand may have a density of 2.6 g / cm3 to 2.7 g / cm3.

[0008] Preferably, the polyvinyl alcohol fiber may have a density of 1.2 g / cm3 to 1.4 g / cm3, a tensile strength of 1,500 MPa to 1,700 MPa, and an elastic modulus of 38 GPa to 42 GPa.

[0009] Preferably, the antifreeze agent may include polydiol, octadecylamine, and hydrophobic modified silica; and

[0010] the polydiol, the octadecylanime, and the hydrophobic modified, silica have a mass ratio of (1.8-2.2):(0.8-1.2):(0.8-1.2).

[0011] Preferably, the water reducer may be an aminosulfonic acid-based superplasticizer, and

[0012] the air entraining agent is sodium dodecylbenzene sulfonate, and the early strength agent is diethanolamine.

[0013] The present disclosure further provides a preparation method of the composite, including the following steps:

[0014] (1) mixing the Portland cement, the fly ash, the quartz sand, the sodium carboxymethyl cellulose, the antifreeze agent, the early strength agent, and the air entraining agent to obtain a solid material;

[0015] (2) mixing the solid material, the water reducer, and water to obtain a slurry; and

[0016] (3) mixing the slurry and the polyvinyl alcohol fiber to obtain the antifreezing and high-ductility composite.

[0017] Preferably, in step (1), the mixing may be conducted by stirring at 135 rpm to 145 rpm for 1 min to 3 min.

[0018] Preferably, in step (2), the mixing may be conducted by stirring at 275 rpm to 295 rpm for 2 min to 4 min.

[0019] Preferably, in step (3), the mixing may be conducted by stirring at 275 rpm to 295 rpm for 2 min to 4 min.

[0020] The present disclosure further provides use of the composite in an expansion joint of a bridge.

[0021] The present disclosure provides an antifreezing and high-ductility composite, including a Portland cement, fly ash, quartz sand, a polyvinyl alcohol fiber, sodium carboxymethyl cellulose, an antifreeze agent, a water reducer, an air entraining agent, an early strength agent, and water. In the present disclosure, the fly ash can effectively enhance an early strength; the sodium carboxymethyl cellulose as a thickener can improve a viscosity between materials; the antifreeze agent can reduce a freezing temperature of concrete to promote growth of a concrete strength below zero; the water reducer reduces an amount of water and improves a strength and durability of the composite, and the early strength agent accelerates hydration of the cement to promote development of an early strength. The present disclosure further provides a preparation method of the antifreezing and high-ductility composite, including: mixing solid materials to obtain a mixture, mixing the mixture with liquid materials fully to obtain a slurry, and mixing the slurry with the polyvinyl alcohol fiber to obtain the composite. The preparation method is simple and efficient, has no special process requirements, and is suitable for large-scale production. The present disclosure further provides use of the composite in an expansion joint of a bridge, to improve a frost resistance and durability of the expansion joint, thereby ensuring a quality of a bridge project. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a freeze-thaw process of an M2 composite in Example 1;

[0023] FIG. 2 shows an appearance of the M2 composite in Example I after freezing and thawing 300 times; and

[0024] FIG. 3 shows an appearance of a cement composite without an antifreeze agent and a polyvinyl alcohol fiber in Example 1 after freezing and thawing 75 times. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present disclosure provides an antifreezing and high-ductility composite, prepared by the following raw materials in parts by weight:

[0026] 250 parts to 330 parts of a Portland cement, 900 parts to 1,100 parts of fly ash, 400 parts to 500 parts of quartz sand, 5 parts to 30 parts of a polyvinyl alcohol fiber, 0.5 parts to 0.7 parts of sodium carboxymethyl cellulose, 5 parts to 6 parts of an antifreeze agent, 6 parts to 7 parts of a water reducer, 2.3 parts to 2.7 parts of an air entraining agent, 3 parts to 3.5 parts of an early strength agent, and 300 parts to 410 parts of water.

[0027] In the present disclosure, there is 250 parts to 330 parts, preferably 260 parts to 320 parts, more preferably 280 parts to 300 parts of the Portland cement.

[0028] In the present disclosure, the Portland cement has a strength grade of preferably 42.5R.

[0029] In the present disclosure, there is 900 parts to 1,100 parts, preferably 950 parts to 1,050 parts, more preferably 980 parts to 1,020 parts of the fly ash.

[0030] In the present disclosure, the fly ash is preferably high-calcium fly ash; the high-calcium fly ash is fly ash with a high calcium oxide content emitted by thermal power plants using lignite and sub-bi luminous coal as a fuel, and is also a material that contains a certain amount of hydraulic crystalline minerals and potentially active substances. Compared with ordinary fly ash, the high-calcium fly ash has a smaller particle size, and has a desirable water-reducing effect and rapid development of the early strength and when being used as a cement, admixture or a concrete admixture.

[0031] In the present disclosure, there is 400 parts to 500 parts, preferably 420 parts to 480 parts, more preferably 440 parts to 460 parts of the quartz sand.

[0032] In the present disclosure, the fly ash has a particle size of preferably 0.45 pm to 2 pm, more preferably 1 pm to 1.4 uni, and further more preferably 1.1 pm to 1.3 pm, and the quartz sand has a density of preferably 2.6 g / cm3 to 2.7 g / cmJ, more preferably 2.62 g / cm3 to 2.68 g / cm3, and further more preferably 2.64 g / cm3 to 2.66 g / cm3.

[0033] In the present disclosure, there is 5 parts to 30 parts, preferably 10 parts to 25 parts, more preferably 15 parts to 20 parts of the polyvinyl alcohol fiber.

[0034] In the present disclosure, the polyvinyl alcohol fiber has a density of preferably 1.2 g / cm3 to 1.4 g / cm3, more preferably 1.25 g / cm3 to 1.35 g / cm3, and further more preferably 1.28 g / cm3 to 1.32 g / cm3, a tensile strength of preferably 1,500 MPa to 1,700 MPa, more preferably 1,550 MPa to 1,650 MPa, and further more preferably 1,580 MPa to 1,620 MPa, and an elastic modulus of preferably 38 GPa to 42 GPa, more preferably 39 GPa to 41 GPa, and further more preferably 39.5 GPa to 40.5 GPa.

[0035] In the present disclosure, the polyvinyl alcohol fiber has a diameter of preferably 0.03 mm to 0.05 mm, more preferably 0,034 mm to 0.046 mm, and further more preferably 0.038 mm to 0.042 mm, an L / D ratio of preferably 290 to 310, more preferably 294 to 306, and further more preferably 298 to 302, a shear length of preferably 10 mm to 14 mm, more preferably 11 mm to 13 mm, and further more preferably 11.5 mm to 12.5 mm, a fineness of preferably 14 dtex to 16 dtex , more preferably 14.4 dtex to 15.6 dtex, and further more preferably 14.8 dtex to 15.2 dtex, and an elongation of preferably 5% to 7%, more preferably 5.4% to 6.6%, and further more preferably 5.8% to 6.2%.

[0036] In the present disclosure, there is 0.5 parts to 0.7 parts, preferably 0.54 parts to 0.66 parts, more preferably 0.58 parts to 0.62 parts of the sodium carboxymethyl cellulose.

[0037] In the present disclosure, the sodium carboxymethyl cellulose can be used as a thickener to increase a viscosity between materials, such that the materials can be kept in a suspended state or an opaque state to form a gel.

[0038] In the present disclosure, there is 5 parts to 6 parts, preferably 5.2 parts to 5.8 parts, more preferably 5.4 parts to 5.6 parts of the antifreeze agent.

[0039] In the present disclosure, the antifreeze agent includes preferably polydiol, octadecyl ami ne, and hydrophobic modified silica.

[0040] In the present disclosure, the polydiol, the octadecyl ami ne, and the hydrophobic modified silica have a mass ratio of preferably (1.8-2.2):(0.8-1.2):(0.8-1.2), more preferably (1.9-2.1):(0.9-1.1):(0.9-1.1), more preferably (1.95-2.05):(0.95-1.05):(0.95-1.05).

[0041] In the present disclosure, the polydiol is preferably polyethylene glycol as an organic compound to lower a freezing point.

[0042] In the present disclosure, the octadecyl amine is used as a surfactant to make the material form a hydrophobic absorption film on a surface.

[0043] In the present disclosure, the hydrophobic modified silica has a density higher than that of water and can float on the water surface, due to hydrophobicity caused by a non-hydrolyzable methyl group attached to a surface.

[0044] In the present disclosure, the antifreeze agent can reduce a freezing temperature of the concrete to promote a strength increase of the concrete below7 zero.

[0045] In the present disclosure, there is 6 parts to 7 parts, preferably 6.2 parts to 6.8 parts, more preferably 6.4 parts to 6.6 parts of the water reducer.

[0046] In the present disclosure, the water reducer is preferably an aminosulfonic acidbased superplasticizer, and the aminosulfonic acid-based superplasticizer is preferably an ASH-JD aminosulfonic acid-based superplasticizer.

[0047] In the present disclosure, the water reducer has an inherent excellent water-reducing property, fluidity and slump retention function, and can improve the strength and durability of composite.

[0048] In the present disclosure, there is 2.3 parts to 2.7 parts, preferably 2.4 parts to 2.6 parts, more preferably 2.45 parts to 2.55 parts of the air entraining agent.

[0049] In the present disclosure, the air entraining agent is preferably sodium dodecylbenzene sulfonate; the air entraining agent can improve workability; water retention and cohesion of the material, and improve fluidity of the concrete.

[0050] In the present disclosure, there is 3 parts to 3.5 parts, preferably 3.1 parts to 3.4 parts, more preferably 3.2 parts to 3.3 parts of the early strength agent.

[0051] In the present disclosure, the early strength agent is preferably diethanolamine; the early strength agent can accelerate the hydration of cement to promote the development of early strength, and has both early strengthening and certain water reduction enhancement functions.

[0052] In the present disclosure, there is 300 parts to 410 parts, preferably 320 parts to 390 parts, more preferably 350 parts to 360 parts of water

[0053] The present di sclosure further provides a preparation method of the composite, including the following steps:

[0054] (1) mixing the Portland cement, the fly ash, the quartz sand, the sodium carboxymethyl cellulose, the antifreeze agent, the early strength agent, and the air entraining agent to obtain a solid material;

[0055] (2) mixing the solid material, the water reducer, and water to obtain a slurry; and

[0056] (3) mixing the slurry and the polyvinyl alcohol fiber to obtain the antifreezing and high-ductility composite.

[0057] In the present disclosure, in step (1), the mixing is conducted preferably by stirring at preferably 135 rpm to 145 rpm, more preferably 136 rpm to 144 rpm, and further more preferably 138 rpm to 142 rpm for preferably 1 min to 3 min, more preferably 15 min to 2.5 min, and further more preferably 1.8 min to 2.2 min.

[0058] In the present disclosure, in step (2), the mixing is conducted preferably by stirring at preferably 275 rpm to 295 rpm, more preferably 280 rpm to 290 rpm, and further more preferably 284 rpm to 286 rpm for preferably 2 min to 4 min, more preferably 2.5 min to 3.5 min, and further more preferably 2.8 min to 3.2 min.

[0059] In the present, disclosure, in step (3), the mixing is conducted preferably by stirring at preferably 275 rpm to 295 rpm, more preferably 280 rpm to 290 rpm, and further more preferably 284 rpm to 286 rpm for preferably 2 min to 4 min, more preferably 2.5 min to 3.5 min, and further more preferably 2.8 min to 3.2 min.

[0060] The present disclosure further provides use of the composite in an expansion joint of a bridge.

[0061] The technical solution provided by the present disclosure will be described in detail below with reference to examples, but they should not be construed as limiting the protection scope of the present disclosure.

[0062] Example 1

[0063] 316 parts of a Portland cement, 947 parts of high-calcium fly ash, 455 parts of quartz sand, 26 parts of a polyvinyl alcohol fiber, 0.6 parts of sodium carboxymethyl cellulose, 5.3 parts of an antifreeze agent, 6.2 parts of an ASH-JD aminosulfonic acidbased superplasticizer, 2.48 parts of sodium dodecylbenzene sulfonate, and 3.1 parts of diethanolamine were weighed.

[0064] The Portland cement had a strength grade of 42.5R, the high-calcium fly ash had a particle size of 1 pm, and quartz sand had a density of 2.65 g / cm3;

[0065] The polyvinyl alcohol fiber had a density of 1.3 g / cm3, a tensile strength of 1,600 MPa, a elastic modulus of 40 GPa, a diameter of 0.04 mm, an L / D ratio of 300, a shear length of 12 mm, a fineness of 15 dtex, and an elongation of 6%; and

[0066] in the antifreeze agent, the polyethylene glycol, the octadecylamine, and the hydrophobic modified silica had a mass ratio of 2:1:1.

[0067] In the example, 303 parts, 354 parts and 404 parts of water were used separately; when 303 parts of water was used, a water-to-binder ratio was 0.24, and a composite obtained was recorded as Ml; when 3 54 parts of water was used, a water-to-binder ratio was 0.28, and a composite obtained was recorded as M2; when 404 parts of water was used, a water-to-binder ratio was 0.32, and a composite obtained was recorded as M3.

[0068] A preparation method included: the Portland cement, the fly ash, the quartz sand, the sodium carboxymethyl cellulose, the antifreeze agent, the diethanolamine, and the sodium dodecyl benzene sulfonate were stirred at 140 rpm for 2 rain to obtain a solid material ; the solid material, the aminosulfonic acid-based superplasticizer, and water were stirred at 285 rpm for 3 min to obtain a slurry; and the slurry and the polyvinyl alcohol fiber were stirred at 285 rpm for 3 min to obtain an antifreezing and high-ductility composite.

[0069] The antifreezing and high-ductility composite was placed in a steel mold of 240 mm x 115 mm x 53 mm for 1 d at room temperature, demolded, and cured in a standard environment for 28 d; an obtained sample was subjected to 300 freeze-thaw cycles at -18°C to 5°C, where each freeze-thaw cycle was completed within 3 h. A freezing and thawing process of M2 was shown in FIG. 1, and an appearance after 300 freeze-thaw cycles was shown in FIG. 2. The antifreeze agent and the polyvinyl alcohol fiber in composite M2 were removed to obtain a cement composite, and a sample was prepared according to the above standards. FIG. 3 show's appearances of different cement composites after freezing and thawing 75 times. It can be seen from FIG. 1 to FIG. 3 that the sample doped with the fiber and antifreeze agent are basically intact after 300 freeze-thaw cycles; while the appearance of the un-doped sample was severely damaged after only 75 freeze-thaw cycles.

[0070] A mass loss rate of the sample was tested while the freeze-thaw cycle was conducted, and results were recorded in Table 1.

[0071] Table 1 Mass loss rate of sample in freeze-thaw cycle

[0072] Mass loss rate (%) 0 freeze thaw cycles 50 freeze thaw cycles 100 freeze- thaw cycles 150 freeze thaw cycles 200 freeze-thaw cycles 250 freeze- 300 freeze- thaw cycles thaw cycles ________________Ml_________________ M2 Q _________-0.05__________ 0.02 -0.2 -0.4 _________-0.05__________ -0.4 -0.05 -0.48 __________-0.2__________1............0____________ -0.25 | -0.8 M3 0 -0.3 -0.5 -0.3 -0.5 -0.75 1 -0.5

[0073] It can be seen from Table 1 that the mass loss rates of three groups of samples Ml, M2 and M3 each are within 1% and are negative, indicating that the mass of sample has increased.

[0074] A relative dynamic elastic modulus of the sample was tested while the freeze-thaw cycle was conducted, and results were recorded in Table 2.

[0075] Table 2 Dynamic elastic modulus of sample in freeze-thaw cycle

[0076] _______________________________________________________________ too 150 200 250 300 Dynamic 0 freeze- 50 freeze- freeze- i reeze- freeze- freeze- freeze- elastic thaw thaw 1haw thaw thaw thaw thaw modulus cycles cycles cycles cycles cycles cycles cycles | MI | 100 99.8 98 97 5 97 96 94.98 1 M2 1 100 99.8 97 9 97 95 94.2 92.78 M3 | 100 98 97 96.4 95 5 93.1 924 5 |

[0077] It can be seen from Table 2 that with an increase of the freeze-thaw cycles, the relative dynamic elastic modulus of the sample gradually decreases with a low decrease amplitude, indicating that, the cement-based composite has a desirable frost resistance.

[0078] Example 2

[0079] 253 parts of a Portland cement, 1,012 parts of high-calcium fly ash, 455 parts of quartz sand, 0.5 parts of sodium carboxymethyl cellulose, 5.2 parts of an antifreeze agent, 6.1 parts of an ASH-JD aminosulfonic acid-based superplasticizer, 2.3 parts of sodium dodecyl benzene sulfonate, 3.1 parts of diethanolamine, and 303 pans of water were weighed.

[0080] The Portland cement had a strength grade of 42.5R, the high-calcium fly ash had a particle size of 1.4 pm, and quartz sand had a density of 2.7 g / cm3;

[0081] The polyvinyl alcohol fiber had a density of 1.3 g / cm3, a tensile strength of 1,600 MPa, a elastic modulus of 40 GPa, a diameter of 0.04 mm, an L / D ratio of 300, a shear length of 12 mm, a fineness of 15 dtex, and an elongation of 6%; and

[0082] in the antifreeze agent, the polyethylene glycol, the octadecylamine, and the hydrophobic modified silica had a mass ratio of 1.9:1.1:0.9.

[0083] In the example, 6.5 parts, 13 parts, 19.5 parts and 26 parts of the polyvinyl alcohol fiber were used separately; when 6.5 parts of the polyvinyl alcohol fiber was used, a composite obtained was recorded as F0.5; when 13 parts of the polyvinyl alcohol fiber was used, a composite obtained was recorded as Fl .0; when 19.5 parts of the polyvinyl alcohol fiber was used, a composite obtained was recorded as FI .5; when 26 parts of the polyvinyl alcohol fiber was used, a composite obtained was recorded as F2.0.

[0084] A preparation method included: the Portland cement, the fly ash, the quartz sand, the sodium carboxymethyl cellulose, the antifreeze agent, the diethanolamine, and the sodium dodecylbenzene sulfonate were stirred at 135 rpm for 3 min to obtain a solid material ; the solid material, the aminosulfonic acid-based superplasticizer, and water were stirred at 295 rpm for 4 min to obtain a slurry; and the slurry and the polyvinyl alcohol fiber were stirred at 275 rpm for 2 rain to obtain an antifreezing and high-ductility composite.

[0085] The performance of the antifreezing and high-ductility composite was tested, where a uniaxial tensile sample had a size of 330 mm * 60 mm x 15 mm; a thin plate four-point bending sample had a size of 400 ram * 100 mm x 100 mm, and a cube compression test sample had a size of 100 mm * 100 mm x 100 mm.

[0086] The sample was subjected to a uniaxial tensile test to determine strain hardening properties of the material, and results were recorded in Table 3.

[0087] Table 3 Uniaxial tensile test results [0088 1 No. Initial Cube crack compressiv strengt e strength h (MPa) (MPa) Initial crack Tensile strength- elastic corresponds moduli; g strain (%) s (MPa) Ultimat e tensile strength (MPa) Ultimat | Nnmbe e tensile j r of strain i cracks (%) | (strips) Averag e crack width (gm) Averag e crack spacing (mm) F0. 5 28.0 2.04 0.01 20.4 1.28 0.41 | - Fl. 0 33.1 2.92 0.01 29.2 2.9 0.72 1 - Fl. 5 38.4 3.29 0.012 39.6 3.59 .. 1. - F2. 0 42.5 3.21 0.096 I 3.37 4.99 5.99 | 21 262 4.38

[0089] As can be seen from Table 3, the three groups F0.5, F1.0, and Fl.5 do not undergo strain hardening, and have only a few cracks, and no crack statistics is conducted. The number of cracks and the width of cracks in the F2.0 group each are more obvious than those of the other three groups, and statistics on the F2.0 group is conducted. The tensile properties of material are quite different due to different volume of additions of the fiber. The addition of fiber leads to an increase in each of the cube compressive strength, initial crack strength, ultimate tensile strain and ultimate tensile strength of the material.

[0090] The sample was subjected to a bending test, and results were recorded in Table

[0091] Table 4 Bending test results Ultimate Ultimate mid- | Maximum Initial crack Initial crack bending ! Energy span I toughness No. strength deflection tensile 1 absorption deflection j index its load- (MPa) (mm) strength | index (K.T / m3) (mm) j deflection (MPa) F0.5 0.33 0.15 4.3 8.35 I 5.2 91 ............................... F1.0 4.13 0.29 8.1 24.8 1 27.0 211 Fl.5 4.98 0.53 8.2 23.4 1 26.8 113 1 F2.0 4.88 1 0.3 12.4 46.8 1 77.2 316 |

[0093] As can be seen from Table 4, with the addition of fiber, the ultimate bending tensile strength and the ultimate mid-span deflection of the four groups each gradually increase, and the energy absorption of fiber also gradually increases. Adding fibers to a material is like adding a lot of chaotically distributed steel bars; after the material is cracked, the fibers above cracks limit development of the cracks, and the material transmit stress to the fibers; and when the stress is less than the ultimate tensile stress of the fibers, the material does not crack. Therefore, adding fibers to the cement-based composite can improve ductility of the material.

[0094] It can be seen from the examples that the present disclosure provides an antifreezing and high-ductility composite. The composite has excellent freeze-thaw cycle stability and ductility, a mass loss rate as low as 0 after 300 freeze-thaw cycles, and a dynamic elastic modulus of 94.98; the composite has a cube compressive strength of 42.5 MPa, an initial crack strength of 3.21 MPa, and an ultimate tensile strength of 4.99 MPa; in the bending test, the composite has an initial crack strength of 4.98 MPa, an initial crack deflection of 0.53 mm, an ultimate bending tensile strength of 12.4 MPa, and an ultimate mid-span deflection of 46.8 mm. From the above data, it is proved that the antifreezing and high-ductility composite has excellent properties.

Claims

1. An antifreezing and high-ductility composite, prepared by the following raw materials in parts by weight:250 parts to 330 parts of a Portland cement, 900 parts to 1 JOO parts of fly ash, 400 parts to 500 parts of quartz sand, 5 parts to 30 parts of a polyvinyl alcohol fiber, 0.5 parts to 0.7 parts of sodium carboxymethyl cellulose, 5 parts to 6 parts of an antifreeze agent, 6 parts to 7 parts of a water reducer, 2.3 parts to 2.7 parts of an air entraining agent, 3 parts to 3.5 parts of an early strength agent, and 300 parts to 410 parts of water, wherein the antifreeze agent comprises polydiol, octadecylamine, and hydrophobic modified silica,the water reducer is an aminosulfonic acid-based superplasticizer,the air entraining agent is sodium dodecylbenzene sulfonate, andthe early strength agent is diethanolamine.

2. The composite according to claim 1, wherein the fly ash has a particle size of 0.45 pm to 2 pm, and the quartz sand has a density of 2.6 g / cm3 to 2.7 g / cm3.

3. The composite according to claim 1 or 2, wherein the polyvinyl alcohol fiber has a density of 1.2 g / cm3 to 1.4 g / cm3, a tensile strength of 1,500 MPa to 1,700 MPa, and an elastic modulus of 38 GPa to 42 GPa.

4. The composite according to claim 3, wherein the polydiol, the octadecylamine, and the hydrophobic modified silica have a mass ratio of (1.8-2.2):(0.8-1.2):(0.8-1.2).

5. A preparation method of the composite according to any one of claims 1 to 4, comprising the following steps:(1) mixing the Portland cement, the fly ash, the quartz sand, the sodium carboxymethyi cellulose, the antifreeze agent, the early strength agent, and the air entraining agent to obtain a solid material;(2) mixing the solid material, the water reducer, and water to obtain a slurry; and(3) mixing the slurry and the polyvinyl alcohol fiber to obtain the antifreezing and high-ductility composite.

6. The preparation method according to claim 5, wherein in step (1), the mixing isconducted by stirring at 135 rpm to 145 rpm for 1 min to 3 min.

7. The preparation method according to claim 5 or 6, wherein in step (2), the mixing is conducted by stirring at 275 rpm to 295 rpm for 2 min to 4 min.

8. The preparation method according to claim 7, wherein in step (3), the mixing is conducted by stirring at 275 rpm to 295 rpm for 2 min to 4 min.

9. Use of the composite according to any one of claims 1 to 4 in an expansion joint of a bridge.

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