A quick-setting repair mortar for cracks in the bottom slab of a cement concrete bridge and its preparation process

Abstract

The present invention relates to the technical field of building materials, and specifically to a fast-setting repair mortar for cracks in cement concrete bridge bottom plates and a preparation process thereof. The present invention uniformly mixes sulphoaluminate cement, quartz sand, polypropylene fiber and mineral admixture as mortar dry material, uniformly mixes polymer emulsion, early strength agent, water reducer, defoamer, nano titanium dioxide and water as a composite solution, pours the composite solution into the mortar dry material, and fully stirs to achieve the synergistic effect of the composite solution and the mortar dry material, thereby effectively improving the uniformity and stability of the mortar. The fast-setting repair mortar prepared by the present invention can quickly fill the cracks of cement concrete bridge bottom plates and has excellent strength, thereby improving the safety and service life of the bridge.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and specifically to a quick-setting repair mortar for cracks in the cement concrete bridge floor slab and its preparation process. Background Art

[0002] As an important part of bearing the traffic load on the bridge deck, the cement concrete bridge floor slab is often affected by factors such as heavy loads, temperature changes, and environmental erosion, resulting in cracks. These cracks not only affect the service life and safety of the bridge, but also cause water and chemical substances to penetrate into the interior of the concrete, accelerating the aging and damage of the concrete. Therefore, repairing the cracks in the bridge floor slab has become an important task for maintaining and servicing the bridge.

[0003] Quick-setting repair mortar has many advantages compared with traditional repair materials. First of all, the quick-setting repair mortar has a relatively fast setting time, can quickly fill the cracks, and quickly restore the normal use of the bridge floor slab. Secondly, it has high bond strength and compressive strength, can effectively enhance the bearing capacity of the bridge floor slab, and improve the safety and stability of the bridge. At the same time, the quick-setting repair mortar also has good durability and impermeability, can effectively prevent the penetration of water and other harmful substances, and extend the service life of the bridge.

[0004] However, there are also some problems with quick-setting repair mortar. Due to its relatively fast setting time, construction workers need to complete the repair work within a short time, which requires relatively high technical requirements; the proportioning and preparation process of quick-setting repair mortar also need to be further studied and improved to meet the repair requirements of different bridge floor slabs.

[0005] Therefore, we propose a quick-setting repair mortar for cracks in the cement concrete bridge floor slab and its preparation process. Summary of the Invention

[0006] The purpose of the present invention is to provide a quick-setting repair mortar for cracks in the cement concrete bridge floor slab and its preparation process to solve the problems raised in the above background art.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] A preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab, comprising the following steps:

[0009] S1: Mix quartz sand and polypropylene fiber, stir at a speed of 100 - 200 r / min for 40 - 60 s, add sulphoaluminate cement and mineral admixture and mix and stir for 30 - 40 s to obtain dry mortar;

[0010] S2: Mix nano-titanium dioxide, water, and polymer emulsion evenly, ultrasonically disperse for 50 - 60 min, add early strength agent, water reducer, and defoamer, mix evenly, and ultrasonically disperse for 50 - 60 min to obtain a composite solution;

[0011] S3: Pour the composite solution prepared in S2 into dry mortar materials, and under vacuum conditions, stir at a speed of 200 - 300 r / min for 160 - 180 s. After mixing evenly, obtain rapid-setting repair mortar.

[0012] Further, the rapid-setting repair mortar includes the following weight components:

[0013] 100 - 120 parts of sulphoaluminate cement, 100 - 150 parts of quartz sand, 10 - 25 parts of mineral admixture, 5 - 15 parts of polymer emulsion, 0.1 - 1.0 part of early strength agent, 0.2 - 1.0 part of water reducer, 0.1 - 1.0 part of defoamer, 0.02 - 0.04 part of nano-titanium dioxide, 1 - 5 parts of polypropylene fiber, and 10 - 30 parts of water.

[0014] Further, the sulphoaluminate cement is rapid-hardening sulphoaluminate cement, and its initial setting time is 5 - 6 min.

[0015] Further, the quartz sand is high-quality quartz sand.

[0016] Further, the mineral admixture consists of 5 - 15 mass parts of fly ash and 5 - 10 mass parts of ground granulated blast-furnace slag.

[0017] Further, the polymer emulsion consists of 2 - 7 mass parts of carboxylated styrene-butadiene latex and 3 - 8 mass parts of ethylene-vinyl acetate copolymer emulsion.

[0018] Further, the early strength agent is calcium formate.

[0019] Further, the preparation method of the water reducer is as follows:

[0020] Step (1): Mix polyethylene glycol methacrylate and dichloromethane evenly, add potassium carbonate and mix evenly, heat up to 40 - 45 °C, dropwise add a mixture of thionyl chloride and dichloromethane, finish dropping in 40 - 50 min, heat up to 45 - 50 °C for condensation reflux for 22 - 24 h, cool to room temperature, filter, and perform rotary evaporation under reduced pressure to obtain reactant A;

[0021] Step (2): Under dark conditions and nitrogen protection, mix reactant A and dimethyl sulfoxide evenly, add potassium iodide and mix evenly, heat up to 85 - 90 °C, dropwise add 3 - amino - 1 - propanol, complete the dropping in 30 - 40 min, reflux for 22 - 24 h, and cool to room temperature; under ice - bath conditions, dropwise add methacryloyl chloride, complete the dropping in 30 - 40 min, react for 22 - 24 h, filter by suction and then rotary evaporate under reduced pressure to obtain reactant B;

[0022] Step (3): Mix reactant B and deionized water evenly, heat up to 40 - 60 °C, dropwise add aqueous ammonium persulfate solution, complete the dropping in 80 - 90 min; simultaneously dropwise add a solution composed of sodium methallylsulfonate, hydroxypropyl acrylate and acrylic acid, complete the dropping in 70 - 80 min, heat up to 70 - 80 °C, keep the temperature for reaction for 3 - 4 h, cool to room temperature, and adjust the pH value to 6 - 7 with 20 - 30 wt% NaOH solution to obtain the water - reducing agent.

[0023] In the above technical solution, thionyl chloride is used as a chlorinating agent to undergo a nucleophilic substitution reaction with the - OH group in polyethylene glycol methacrylate to obtain reactant A; then, with 3 - amino - 1 - propanol as the core, react with reactant A to graft the polyethylene glycol long chain onto the - NH2 of 3 - amino - 1 - propanol, add an excessive amount of reactant A to ensure that both hydrogen atoms on - NH2 are substituted; then add methacryloyl chloride to introduce a double bond to obtain reactant B; using ammonium persulfate as an initiator, sodium methallylsulfonate as a chain transfer agent, reactant B as a macromonomer, hydroxypropyl acrylate and acrylic acid as comonomers, synthesize the water - reducing agent through free - radical copolymerization reaction. The water - reducing agent of the present invention has a larger steric hindrance and excellent dispersion performance, and has various beneficial effects on rapid - setting repair mortar, including improving fluidity, promoting early strength development, improving durability and crack - resistance performance, etc.

[0024] Further, in step (1), the mass ratio of polyethylene glycol methacrylate to dichloromethane is 1:(2 - 3).

[0025] Further, in step (1), the dosage of potassium carbonate is 50 - 60% of the mass of polyethylene glycol methacrylate.

[0026] Further, in step (1), the mass ratio of thionyl chloride to dichloromethane is 1:(1.5 - 2.0), and the mass of thionyl chloride is 1 - 2 times the mass of polyethylene glycol methacrylate.

[0027] Further, in step (2), the mass ratio of reactant A to dimethyl sulfoxide is 1:(2 - 3).

[0028] Further, in step (2), the dosage of potassium iodide is 4 - 6% of the mass of reactant A.

[0029] Further, in the step (2), the 3-amino-1-propanol is 10-12% of the mass of reactant A.

[0030] Further, in the step (2), the mass of methacryloyl chloride is 30-40% of the mass of reactant A.

[0031] Further, in the step (3), the mass ratio of reactant B to deionized water is 1:(2-4).

[0032] Further, in the step (3), the concentration of the ammonium persulfate aqueous solution is 10-15 wt%, and the mass of ammonium persulfate is 3-5% of the mass of reactant A.

[0033] Further, in the step (3), the mass of sodium methallylsulfonate is 16-18% of the mass of reactant B.

[0034] Further, in the step (3), the mass ratio of reactant B, hydroxypropyl acrylate and acrylic acid is 1:(0.1-0.2):(0.2-0.3).

[0035] Further, the nano-titanium dioxide is surface-treated, and the specific steps are as follows:

[0036] Mix the nano-titanium dioxide and deionized water evenly, heat up to 70-80 °C, adjust the pH value of the system to 4-5, add γ-methacryloyloxypropyltrimethoxysilane, stir magnetically for 30-40 min, and ultrasonically disperse for 20-30 min; centrifuge at a speed of 8000-10000 r / min for 10-20 min and then wash, repeat 1-3 times, and vacuum dry at 100-110 °C for 24-48 h to obtain.

[0037] Further, the mass ratio of the nano-titanium dioxide to deionized water is 1:(180-200).

[0038] Further, the mass of γ-methacryloyloxypropyltrimethoxysilane is 0.5-1.0% of the total mass of the nano-titanium dioxide and deionized water.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. Preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab. By uniformly mixing sulfoaluminate cement, quartz sand, polypropylene fiber, and mineral admixture as the dry mortar material, and uniformly mixing polymer emulsion, early strength agent, water reducer defoamer, nano-titanium dioxide powder, and water as the composite solution, then pouring the composite solution into the dry mortar material and fully stirring to achieve the synergistic effect of the composite solution and the dry mortar material, effectively improving the uniformity and stability of the mortar. At the same time, according to specific needs, the proportion of the mortar can be adjusted to meet the requirements of different projects. In this process, sulfoaluminate cement, as the main cementing material, can provide good bonding performance; quartz sand, as the aggregate, can increase the strength and stability of the mortar; the addition of polypropylene fiber can improve the crack resistance of the mortar; the addition of mineral admixture can improve the impermeability and durability of the mortar; at the same time, the polymer emulsion in the composite solution can increase the bonding force and flexibility of the mortar, the early strength agent can promote the early strength development of the mortar, the water reducer can adjust the fluidity of the mortar, and the defoamer can effectively eliminate the air bubbles in the mortar. In addition, the addition of nano-titanium dioxide powder can improve the anti-ultraviolet performance and self-cleaning performance of the mortar.

[0041] 2. Preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab. Using thionyl chloride as the chlorinating agent to carry out a nucleophilic substitution reaction with the -OH group in polyethylene glycol methacrylate to obtain reactant A; then, with 3-amino-1-propanol as the core, graft the polyethylene glycol long chain in reactant A onto the -NH2 of 3-amino-1-propanol, and add an excessive amount of reactant A to ensure that both hydrogen atoms on the -NH2 are substituted; then add methacryloyl chloride to introduce a double bond to obtain reactant B; using ammonium persulfate as the initiator, sodium methallylsulfonate as the chain transfer agent, reactant B as the macromonomer, hydroxypropyl acrylate and acrylic acid as the small monomers, and synthesize the water reducer through free radical copolymerization reaction. The polyglycol chain is introduced into the molecular structure of this water reducer, making it have a larger steric hindrance, thus being able to effectively regulate the interaction between cement particles, reduce the friction and cohesion between particles, improve the fluidity of the mortar, and make it easier to construct and fill the cracks. Secondly, the water reducer can improve the early strength development of the mortar, enabling the repaired mortar to reach the use requirements faster. In addition, the water retention performance of the water reducer can reduce the water evaporation of the mortar and improve the durability and crack resistance of the repair mortar. Detailed implementation mode

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] In this embodiment, the sulfoaluminate cement is rapid hardening sulfoaluminate cement, with an initial setting time of 5 - 6 minutes, product number JH - 87, and the sulfur trioxide content not exceeding 3.5%. It is sourced from Wuxi Jianghuai Building Materials Technology Co., Ltd.; the quartz sand is high - quality quartz sand, with a silicon dioxide content of ≥99.9%, 20 - 40 mesh, sourced from Changxing Qingsheng Calcium Industry Co., Ltd.; the fly ash is first - class fly ash, 325 mesh, sourced from Lingshou Yaoxin Mineral Products Processing Factory; the mineral powder is S95 - grade mineral powder, 20 - 45μm, sourced from Hebei Yousheng Refractory Materials Co., Ltd.; the carboxy styrene - butadiene latex is BASF Styronal 7946, with a solid content of 49 - 51%, sourced from Guangdong Gaobafu Technology Trading Company; the vinyl acetate - ethylene copolymer emulsion is Wacker Vinnapas EP707K, with a solid content of up to 74% (usually 50%), sourced from Shanghai Kayin Chemical Co., Ltd.; the calcium formate is sourced from Shandong Ruihongde Chemical Technology Co., Ltd.; the defoamer is model B - 132, with an active substance content of 60 - 99% and a pH value of 5 - 8, sourced from Guangdong Zhonglianbang Fine Chemical Co., Ltd.; the polyethylene glycol methacrylate has an average molecular weight of 475, sourced from Shanghai Aladdin Biochemical Technology Co., Ltd.; the nano - titanium dioxide is rutile type, DuPont R - 900 from the United States, with a median particle size of 0.3μm, sourced from Shanghai Heli Fine Chemical Co., Ltd.; the polypropylene fiber has a fiber diameter of 2.5μm and a length of 3 - 10mm, sourced from Shanghai Lingyu Building Materials Co., Ltd.

[0044] In the following examples and comparative examples, 1 part is equal to 10g.

[0045] Example 1: A preparation process for rapid - setting repair mortar for cracks in the bridge floor slab of cement concrete, including the following processes:

[0046] A preparation process for rapid - setting repair mortar for cracks in the bridge floor slab of cement concrete includes the following steps:

[0047] S1: Mix 100 parts of quartz sand and 1 part of polypropylene fiber, stir at a speed of 100r / min for 40s, add 100 parts of sulfoaluminate cement, 5 parts of fly ash, and 5 parts of mineral powder, and stir for 30s to obtain dry mortar.

[0048] S2: Mix 0.02 parts of nano - titanium dioxide, 10 parts of water, 2 parts of carboxy styrene - butadiene latex, and 3 parts of vinyl acetate - ethylene copolymer emulsion evenly, disperse ultrasonically for 50min, add 0.1 part of calcium formate, 0.2 part of water - reducing agent, and 0.1 part of defoamer, mix evenly, and disperse ultrasonically for 50min to obtain a composite solution.

[0049] S3: Pour the composite solution prepared in S2 into the dry mortar, and under vacuum conditions, stir at a speed of 200r / min for 160s. After mixing evenly, obtain the rapid - setting repair mortar.

[0050] The preparation method of the water reducing agent is as follows:

[0051] Step (1): Mix 0.2 parts of polyethylene glycol methacrylate and 0.4 parts of dichloromethane evenly, add 0.1 part of potassium carbonate and mix evenly, heat up to 40 °C, dropwise add a mixture of 0.2 parts of thionyl chloride and 0.3 parts of dichloromethane, finish dropping in 40 min, heat up to 45 °C and carry out condensation reflux for 22 h, cool to room temperature, filter and carry out rotary evaporation under reduced pressure to obtain reactant A;

[0052] Step (2): Under dark conditions and nitrogen protection, mix 0.2 parts of reactant A and 0.4 parts of dimethyl sulfoxide evenly, add 0.008 part of potassium iodide and mix evenly, heat up to 85 °C, dropwise add 0.02 part of 3-amino-1-propanol, finish dropping in 30 min, carry out reflux reaction for 22 h, cool to room temperature; under ice bath conditions, dropwise add 0.06 part of methacryloyl chloride, finish dropping in 30 min, react for 22 h, carry out suction filtration and then rotary evaporation under reduced pressure to obtain reactant B;

[0053] Step (3): Mix 0.2 parts of reactant B and 0.4 parts of deionized water evenly, heat up to 40 °C, dropwise add 0.06 g of 10 wt% ammonium persulfate aqueous solution, finish dropping in 80 min; at the same time, dropwise add a solution composed of 0.032 part of sodium methallylsulfonate, 0.02 part of hydroxypropyl acrylate and 0.04 part of acrylic acid, finish dropping in 70 min, heat up to 70 °C, keep the temperature for reaction for 3 h, cool to room temperature, and adjust the pH value to 6 with 20 wt% NaOH solution to obtain the water reducing agent;

[0054] The nano-titanium dioxide is surface-treated, and the specific steps are as follows:

[0055] Mix 0.02 part of nano-titanium dioxide and 3.6 parts of deionized water evenly, heat up to 70 °C, adjust the pH value of the system to 4, add 0.018 part of γ-methacryloyloxypropyltrimethoxysilane, stir magnetically for 30 min, disperse ultrasonically for 20 min; centrifuge at a speed of 8000 r / min for 20 min and then wash, repeat once, and dry in vacuum at 100 °C for 24 h to obtain it.

[0056] Example 2: The preparation process of a quick-setting repair mortar for cracks in the bottom slab of a cement concrete bridge includes the following processes:

[0057] S1: Mix 130 parts of quartz sand and 3 parts of polypropylene fiber, stir at a rotation speed of 150 r / min for 50 s, add 110 parts of sulfoaluminate cement, 8 parts of fly ash and 7 parts of mineral powder and mix and stir for 35 s to obtain dry mortar;

[0058] S2: Mix 0.03 parts of nano-titanium dioxide, 20 parts of water, 5 parts of carboxy styrene-butadiene latex, and 6 parts of vinyl acetate-ethylene copolymer emulsion evenly, ultrasonically disperse for 55 min, add 0.5 parts of calcium formate, 0.6 parts of water reducing agent, and 0.5 parts of defoamer and mix evenly, then ultrasonically disperse for 55 min to obtain a composite solution;

[0059] S3: Pour the composite solution prepared in S2 into the dry mortar material, and under vacuum conditions, stir at a speed of 250 r / min for 170 s. After mixing evenly, a quick-setting repair mortar is obtained;

[0060] The preparation method of the water reducing agent is as follows:

[0061] Step (1): Mix 0.6 parts of polyethylene glycol methacrylate and 1.5 parts of dichloromethane evenly, add 0.33 parts of potassium carbonate and mix evenly, heat up to 42 °C, dropwise add a mixture of 0.9 parts of thionyl chloride and 1.62 parts of dichloromethane, finish dropping in 45 min, heat up to 48 °C and carry out condensation reflux for 23 h, cool to room temperature, filter and carry out rotary evaporation under reduced pressure to obtain reactant A;

[0062] Step (2): Under dark conditions and nitrogen protection, mix 0.6 parts of reactant A and 1.5 parts of dimethyl sulfoxide evenly, add 0.03 parts of potassium iodide and mix evenly, heat up to 87 °C, dropwise add 0.066 parts of 3-amino-1-propanol, finish dropping in 35 min, carry out reflux reaction for 23 h, and cool to room temperature; under ice bath conditions, dropwise add 0.21 parts of methacryloyl chloride, finish dropping in 35 min, react for 23 h, carry out suction filtration and rotary evaporation under reduced pressure to obtain reactant B;

[0063] Step (3): Mix 0.6 parts of reactant B and 1.8 parts of deionized water evenly, heat up to 50 °C, dropwise add 0.2 parts of 12 wt% ammonium persulfate aqueous solution, finish dropping in 85 min; at the same time, dropwise add a solution composed of 0.1 parts of sodium methallylsulfonate, 0.09 parts of hydroxypropyl acrylate, and 0.15 parts of acrylic acid, finish dropping in 75 min, heat up to 75 °C, keep the temperature for reaction for 3.5 h, cool to room temperature, and adjust the pH value to 6 with 25 wt% NaOH solution to obtain the water reducing agent;

[0064] The nano-titanium dioxide is surface-treated, and the specific steps are as follows:

[0065] Mix 0.03 parts of nano-titanium dioxide and 5.7 parts of deionized water evenly, heat up to 75 °C, adjust the pH value of the system to 4, add 0.045 parts of γ-methacryloyloxypropyltrimethoxysilane, stir magnetically for 35 min, and ultrasonically disperse for 25 min; centrifuge at a speed of 9000 r / min for 15 min and then wash, repeat 2 times, and dry under vacuum at 105 °C for 36 h to obtain it.

[0066] Example 3: A preparation process of a quick-setting repair mortar for cracks in the bottom slab of a cement concrete bridge, including the following processes:

[0067] S1: Mix 150 parts of quartz sand and 5 parts of polypropylene fiber, stir at a speed of 200 r / min for 60 s, add 120 parts of sulfoaluminate cement, 15 parts of fly ash, and 10 parts of mineral powder, and stir for 40 s to obtain dry mortar;

[0068] S2: Mix 0.04 part of nano-titanium dioxide, 30 parts of water, 7 parts of carboxylated styrene-butadiene latex, and 8 parts of ethylene-vinyl acetate copolymer latex evenly, ultrasonically disperse for 60 min, add 1.0 part of calcium formate, 1.0 part of water reducer, and 1.0 part of defoamer, mix evenly, and ultrasonically disperse for 60 min to obtain a composite solution;

[0069] S3: Pour the composite solution prepared in S2 into the dry mortar, stir at a speed of 300 r / min for 180 s under vacuum conditions, and mix evenly to obtain a quick-setting repair mortar;

[0070] The preparation method of the water reducer is as follows:

[0071] Step (1): Mix 1 part of polyethylene glycol methacrylate and 3 parts of dichloromethane evenly, add 0.6 part of potassium carbonate and mix evenly, heat up to 45 °C, dropwise add a mixture of 2 parts of thionyl chloride and 4 parts of dichloromethane, finish dropping in 50 min, heat up to 50 °C and carry out condensation reflux for 24 h, cool to room temperature, filter and carry out rotary evaporation under reduced pressure to obtain reactant A;

[0072] Step (2): Under dark conditions and nitrogen protection, mix 1 part of reactant A and 3 parts of dimethyl sulfoxide evenly, add 0.06 part of potassium iodide and mix evenly, heat up to 90 °C, dropwise add 0.12 part of 3-amino-1-propanol, finish dropping in 40 min, carry out reflux reaction for 24 h, and cool to room temperature; under ice bath conditions, dropwise add 0.4 part of methacryloyl chloride, finish dropping in 40 min, react for 24 h, carry out suction filtration and then rotary evaporation under reduced pressure to obtain reactant B;

[0073] Step (3): Mix 1 part of reactant B and 4 parts of deionized water evenly, heat up to 60 °C, dropwise add 0.33 part of 15 wt% ammonium persulfate aqueous solution, finish dropping in 90 min; at the same time, dropwise add an aqueous solution composed of 0.18 part of sodium methallylsulfonate, 0.2 part of hydroxypropyl acrylate, and 0.3 part of acrylic acid, finish dropping in 80 min, heat up to 80 °C, keep warm and react for 4 h, cool to room temperature, and adjust the pH value to 7 with 30 wt% NaOH solution to obtain the water reducer.

[0074] The nano-titanium dioxide is surface-treated, and the specific steps are as follows:

[0075] Mix 0.04 parts of nano-titanium dioxide and 8 parts of deionized water evenly, heat up to 80 °C, adjust the pH value of the system to 5, add 0.08 parts of γ-methacryloxypropyltrimethoxysilane, stir magnetically for 40 min, and disperse ultrasonically for 30 min; centrifuge at a speed of 10,000 r / min for 20 min and then wash, repeat 3 times, and dry in vacuum at 110 °C for 24 h to obtain.

[0076] Comparative Example 1: The quick-setting repair mortar comprises the following weight components: 100 parts of sulfoaluminate cement, 100 parts of quartz sand, 5 parts of fly ash, 5 parts of slag powder, 2 parts of carboxy styrene butadiene latex, 3 parts of ethylene-vinyl acetate copolymer emulsion, 0.1 part of calcium formate, 0.2 part of polycarboxylate water reducer, 0.1 part of defoamer, 0.02 parts of nano-titanium dioxide, 1 part of polypropylene fiber, and 10 parts of water; in Comparative Example 1, the water reducer is replaced with a common polycarboxylate water reducer (product number JT-072, sourced from Shandong Jingtian New Building Materials Co., Ltd.), and the other steps and processes are the same as those in Example 1.

[0077] Comparative Example 2: The quick-setting repair mortar comprises the following weight components: 100 parts of sulfoaluminate cement, 100 parts of quartz sand, 5 parts of fly ash, 5 parts of slag powder, 0.1 part of carboxy styrene butadiene latex, 0.1 part of ethylene-vinyl acetate copolymer emulsion, 0.1 part of calcium formate, 0.2 part of water reducer, 0.1 part of defoamer, 0.02 parts of nano-titanium dioxide, 1 part of polypropylene fiber, and 10 parts of water; compared with Example 1, in Comparative Example 2, the addition amounts of carboxy styrene butadiene latex and ethylene-vinyl acetate copolymer emulsion are reduced, and the other steps are the same as those in Example 1.

[0078] Comparative Example 3: A preparation process of a quick-setting repair mortar for cracks in the bridge floor slab of cement concrete, comprising the following processes:

[0079] Compared with Example 2, the preparation method of the water reducer in Comparative Example 3 is as follows:

[0080] Step (1): Mix 0.6 parts of polyethylene glycol methacrylate and 1.5 parts of dichloromethane evenly, add 0.33 parts of potassium carbonate and mix evenly, heat up to 42 °C, dropwise add a mixture of 0.9 parts of thionyl chloride and 1.62 parts of dichloromethane, finish dropping in 45 min, heat up to 48 °C and carry out condensation reflux for 23 h, cool to room temperature, filter and carry out rotary evaporation under reduced pressure to obtain reactant A;

[0081] Step (2): Under dark conditions and nitrogen protection, mix 0.6 parts of reactant A and 1.5 parts of dimethyl sulfoxide evenly, add 0.03 parts of potassium iodide and mix evenly, heat up to 87 °C, dropwise add 0.066 parts of 3-amino-1-propanol, finish dropping in 35 min, carry out reflux reaction for 23 h, and cool to room temperature; under ice bath conditions, dropwise add 0.21 parts of methacryloyl chloride, finish dropping in 35 min, react for 23 h, carry out suction filtration and then rotary evaporation under reduced pressure to obtain reactant B;

[0082] Step (3): Mix 0.6 parts of reactant B and 1.8 parts of deionized water evenly, heat up to 50 °C, and dropwise add 0.2 parts of 12 wt% ammonium persulfate aqueous solution, which is added dropwise within 85 min; at the same time, dropwise add a solution composed of 0.1 part of sodium methallylsulfonate, 0.6 parts of hydroxypropyl acrylate, and 0.6 parts of acrylic acid, which is added dropwise within 75 min, heat up to 75 °C, keep the temperature for reaction for 3.5 h, cool to room temperature, and adjust the pH value to 6 using 25 wt% NaOH solution to obtain a water reducing agent.

[0083] Compared with Example 2, in Comparative Example 3, the mass ratio of reactant B, hydroxypropyl acrylate, and acrylic acid is 1:1:1; the remaining steps are the same as those in Example 2.

[0084] Experiment

[0085] Take the quick-setting repair mortar obtained in Examples 1 - 3 and Comparative Examples 1 - 3 to prepare specimens, and detect their performance respectively and record the test results:

[0086] Determine the flexural strength and compressive strength according to GB / T 17671 - 2021 "Test Method for Strength of Cement Mortar (ISO)". Experimental steps: Make the specimens into prismatic samples of 40 mm × 40 mm × 160 mm, put the specimens into a curing box for specimens with molds, ensure that the temperature of the curing box remains at 20 °C and the relative humidity is not less than 90%. Test after curing for 7 d and 28 d respectively. Use a flexural strength testing machine to measure the flexural strength of the cured samples. Apply the load vertically and evenly on the opposite sides of the prism at a rate of 50 N / s until it breaks, and record the data. The flexural strength calculation formula is as follows: R f = 1.5F f L / b 3 , where R f is the flexural strength, with the unit of megapascal; F f is the load applied to the middle of the prism at the time of breaking; L is the distance between the support cylinders, with the unit of millimeter; b is the side length of the square cross-section of the prism, with the unit of millimeter. After the flexural strength test is completed, take out the two half specimens and use a compressive strength testing machine to measure the compressive strength. Apply the load evenly at a rate of 2400 N / s throughout the loading process until it fails, and record the data. The compressive strength calculation formula is as follows: R c = F c / A, where R c is the compressive strength, with the unit of megapascal; F c is the maximum load at the time of failure, with the unit of newton; A is the compression area, with the unit of square millimeter.

[0087] Determine the setting time according to JC / T 2381-2016 "Repair Mortar". Experimental steps: Use a test sieve to screen out the mortar from the concrete mixture, and then stir the screened mortar evenly; Fill the mortar into three specimen cylinders at one time, and use an oscillator to fully mix the mortar specimen with water until a uniform paste state is achieved. Place the container in the oscillator and start the oscillator to oscillate at a fixed frequency and amplitude. The oscillation frequency is 1.25 Hz and the amplitude is 1.27 mm. Observe the changes in the specimen, including color, fluidity, surface flatness, etc. After each oscillation, gently touch the surface of the specimen with your fingertips. When the surface of the specimen is no longer sticky and can withstand light pressure, it is the setting time. Record the setting time of the specimen, and repeat the experiment as needed to obtain accurate results. At the same time, the appearance changes and touch feelings of the specimen can also be recorded.

[0088] Test results

[0089]

[0090]

[0091] According to the data in the above table, the following conclusions can be clearly obtained:

[0092] 1. Compared with Examples 1-3, the compressive strength, flexural strength, and setting performance of Comparative Example 1 all decreased, indicating that compared with ordinary polycarboxylate water reducers, the water reducer prepared by the present invention is more beneficial to the performance of the mortar and can better maintain the performance of the mortar.

[0093] 2. Compared with Examples 1-3, the compressive strength, flexural strength, and setting performance of the product obtained in Comparative Example 2 all decreased, which shows that adding the carboxylated styrene-butadiene latex and vinyl acetate-ethylene copolymer latex in the ratio described in the present invention has a better effect, thereby improving the compressive strength, flexural strength, and setting performance of the mortar.

[0094] 3. Compared with Examples 1-3, the compressive strength, flexural strength, and setting of the product obtained in Comparative Example 3 all decreased, indicating that the performance of the water reducer prepared by the present invention is affected by the reagent ratio in the preparation process of its absorbent. Selecting the mass ratio within the described range can prepare a water reducer that can reduce the water evaporation of the mortar, improve the compressive strength and flexural strength of the repair mortar, and reduce the setting time.

[0095] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0096] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation process of a quick-setting repair mortar for cracks in the bridge floor slab of cement concrete, characterized in that: It includes the following steps: S1: Mix quartz sand and polypropylene fiber, stir at a speed of 100 - 200 r / min for 40 - 60 s, add sulfoaluminate cement and mineral admixture and mix and stir for 30 - 40 s to obtain dry mortar material; S2: Mix nano - titanium dioxide, water and polymer emulsion evenly, ultrasonically disperse for 50 - 60 min, add early strength agent, water - reducing agent and defoaming agent and mix evenly, then ultrasonically disperse for 50 - 60 min to obtain composite solution; S3: Pour the composite solution prepared in S2 into the dry mortar material, stir at a speed of 200 - 300 r / min for 160 - 180 s under vacuum conditions, and after mixing evenly, obtain rapid - setting repair mortar; The preparation method of the water - reducing agent is as follows: Step (1): Mix polyethylene glycol methacrylate and dichloromethane evenly, add potassium carbonate and mix evenly, heat up to 40 - 45 °C, dropwise add the mixed solution of thionyl chloride and dichloromethane, finish dropping in 40 - 50 min, heat up to 45 - 50 °C for condensation reflux for 22 - 24 h, cool to room temperature, filter and carry out rotary evaporation under reduced pressure to obtain reactant A; Step (2): Under dark conditions and nitrogen protection, mix reactant A and dimethyl sulfoxide evenly, add potassium iodide and mix evenly, heat up to 85 - 90 °C, dropwise add 3 - amino - 1 - propanol, finish dropping in 30 - 40 min, carry out reflux reaction for 22 - 24 h, cool to room temperature; under ice - bath conditions, dropwise add methacryloyl chloride, finish dropping in 30 - 40 min, react for 22 - 24 h, carry out suction filtration and then rotary evaporation under reduced pressure to obtain reactant B; Step (3): Mix reactant B and deionized water evenly, heat up to 40 - 60 °C, dropwise add ammonium persulfate aqueous solution, finish dropping in 80 - 90 min; at the same time, dropwise add the solution composed of sodium methallylsulfonate, hydroxypropyl acrylate and acrylic acid, finish dropping in 70 - 80 min, heat up to 70 - 80 °C, keep the temperature for reaction for 3 - 4 h, cool to room temperature, and use 20 - 30 wt% NaOH solution to adjust the pH value to 6 - 7 to obtain the water - reducing agent; The rapid - setting repair mortar includes the following weight components: 100 - 120 parts of sulfoaluminate cement, 100 - 150 parts of quartz sand, 10 - 25 parts of mineral admixture, 5 - 15 parts of polymer emulsion, 0.1 - 1.0 part of early strength agent, 0.2 - 1.0 part of water - reducing agent, 0.1 - 1.0 part of defoaming agent, 0.02 - 0.04 part of nano - titanium dioxide, 1 - 5 parts of polypropylene fiber, 10 - 30 parts of water; The polymer emulsion is composed of 2 - 7 mass parts of carboxylated styrene - butadiene emulsion and 3 - 8 mass parts of vinyl acetate - ethylene copolymer emulsion; In step (3), the mass ratio of reactant B, hydroxypropyl acrylate and acrylic acid is 1:(0.1 - 0.2):(0.2 - 0.3).

2. The preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab according to claim 1, characterized in that: The mineral admixture is composed of 5 - 15 mass parts of fly ash and 5 - 10 mass parts of slag powder.

3. The preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab according to claim 1, characterized in that: In step (1), the mass ratio of polyethylene glycol methacrylate and dichloromethane is 1:(2 - 3).

4. The preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab according to claim 1, characterized in that: In step (2), 3 - amino - 1 - propanol is 10 - 12% of the mass of reactant A.

5. The preparation process of a quick-setting repair mortar for cracks in the cement concrete bridge floor slab according to claim 1, characterized in that: The nano - titanium dioxide is surface - treated, and the specific steps are as follows: Mix nano-titanium dioxide and deionized water evenly, heat up to 70 - 80 °C, adjust the pH value of the system to 4 - 5, add γ-methacryloxypropyltrimethoxysilane, stir magnetically for 30 - 40 min, and disperse ultrasonically for 20 - 30 min; centrifuge at a speed of 8000 - 10000 r / min for 10 - 20 min and then wash, repeat 1 - 3 times, and dry in vacuum at 100 - 110 °C for 24 - 48 h to obtain.

6. A quick-setting repair mortar for cracks in the bridge floor slab of cement concrete, prepared by the preparation process according to any one of claims 1 - 5.

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