CN-121974640-A - Negative temperature type rapid hardening early strength repair mortar and preparation method thereof

Abstract

The invention provides negative temperature type quick hardening early strength repair mortar and a preparation method thereof. The invention relates to negative temperature type rapid hardening early strength repair mortar which is suitable for concrete in high and cold areas, and the preparation raw materials comprise rapid hardening sulphoaluminate cement, a heat activator, reference cement, mineral admixture, polyacrylate redispersibility emulsion powder, fiber, negative temperature admixture, nano material, defoamer, fine aggregate, water reducer and water. The repair mortar has good early compressive strength and bonding strength, ensures the continuous development of middle and later-stage performance, does not collapse, and can meet the repair requirement of infrastructure in a negative temperature environment. The invention also provides a preparation method of the negative temperature type rapid hardening early strength repair mortar.

Inventors

• CHEN YIHAN
• WEN CHENGWEI
• GUO HONG
• PAN ZILI
• ZENG XIAOHUI
• ZENG YONGPING
• ZHU HUASHENG
• DONG JUN
• XU JINGMANG
• YANG BINGZHONG
• LONG GUANGCHENG
• TANG ZHUO

Assignees

• 中南大学
• 海南大学
• 西南交通大学
• 湖南铁科轨道科技有限公司
• 中铁十七局集团有限公司
• 中铁二院工程集团有限责任公司

Dates

Publication Date

20260505

Application Date

20260129

Claims (10)

1. 1. The negative temperature type quick hardening early strength repair mortar is characterized by comprising the following preparation raw materials in parts by weight: 70-90 parts of quick hardening sulphoaluminate cement, 1-2 Parts of a thermal activator, 10-30 Parts of reference cement, 10-20 Parts of mineral admixture, 1-3 Parts of polyacrylate redispersible emulsion powder, 2-6 Parts of fiber, 0.1-1 Part of negative temperature additive, 1-3 Parts of nano material, 0.02-0.05 Part of defoaming agent, 90-130 Parts of fine aggregate, 0.5 To 1.5 parts of water reducer, 20-30 Parts of water.
2. 2. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the rapid hardening sulphoaluminate cement comprises r.sac 42.5 grade cement and/or the reference cement comprises p.i 42.5 grade cement.
3. 3. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the thermal activator comprises calcium oxide.
4. 4. The negative temperature type rapid hardening early-strength repair mortar according to claim 1, wherein the mineral admixture comprises at least one of fly ash, mineral powder and silica fume, and/or the mineral admixture is a mixture of fly ash, mineral powder and silica fume, wherein the fly ash is class II fly ash, the amount of the fly ash is 50-75wt% of the total amount of the mineral admixture, the mineral powder is class S95 mineral powder, the amount of the mineral admixture is 15-30wt% of the total amount of the mineral admixture, the SiO 2 content in the silica fume is more than 95%, and the amount of the mineral admixture is 10-20wt% of the total amount of the mineral admixture.
5. 5. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the fiber comprises at least one of copper plated steel fiber and polypropylene fiber.
6. 6. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the negative temperature admixture comprises at least one of an early strength agent and an antifreezing agent.
7. 7. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the nanomaterial comprises at least one of nano silica, nano C-S-H seed crystal, and carbon nanotube.
8. 8. The negative temperature type quick hardening early strength repair mortar according to claim 1, wherein the defoamer comprises at least one of an organosilicon defoamer, a polyether defoamer and a higher alcohol defoamer.
9. 9. The negative temperature type rapid hardening early strength repair mortar according to claim 1, wherein the fine aggregate comprises quartz sand.
10. 10. A method for preparing the negative temperature type rapid hardening early strength repair mortar according to any one of claims 1 to 9, comprising the steps of: S1, mixing the rapid hardening sulphoaluminate cement, the reference cement, the mineral admixture, the fiber, the polyacrylate redispersibility emulsion powder, the thermal activator, the defoamer and the fine aggregate according to a proportion, and then placing the mixture in a stirrer to stir to obtain a repair mortar premix; and S2, adding the ultrasonic dispersion liquid into the repair mortar premix to obtain the negative temperature type rapid hardening early strength repair mortar.

Description

Negative temperature type rapid hardening early strength repair mortar and preparation method thereof Technical Field The invention belongs to the technical field of building materials, and particularly relates to negative temperature type rapid hardening early strength repair mortar and a preparation method thereof. Background In high-cold areas with high latitude and high altitude, the climate conditions are extremely severe, the annual average air temperature is low, the winter is long and severe, and the air temperature is always below the freezing point. In such special environments, concrete structural infrastructures, such as highway pavements, bridges, airport runways, and the like, which bear critical socioeconomic functions, have long faced multiple rigors. The continuous action of mechanical load, strong ultraviolet radiation, complex chemical weathering, repeated freeze thawing cycle and other factors are mutually coupled, so that the concrete structure is continuously eroded, various damage problems such as cracks, peeling, strength reduction and the like are caused, the structural integrity and service performance are seriously affected, the safety and stability operation of the infrastructure are greatly threatened, and the repair construction needs to be carried out in time to restore the use function of the infrastructure. However, concrete structure repair in alpine regions faces special construction dilemmas. Because the infrastructures are core facilities in the key fields of transportation, transportation and the like, and the operation interruption of the infrastructures causes chain reaction and huge social and economic losses, the repair construction is often required to be completed quickly and efficiently, which means that engineering must be developed instantly under low-temperature and even negative-temperature environments. On the one hand, the low temperature can obviously inhibit the hydration reaction rate of cement, so that the setting time of the repair mortar is greatly prolonged, the early strength development is extremely slow, even the repair mortar is possibly completely stagnant, the design strength requirement cannot be met within a specified time, and the progress and quality of repair engineering are affected, on the other hand, free water which does not timely participate in the hydration reaction in the repair mortar can be coagulated into ice to generate volume expansion, and further internal stress concentration is caused, so that micro cracks appear in the mortar structure, low-temperature freeze injury is caused, and the durability and the service life of the repair mortar are seriously reduced. In order to solve the difficult problem of low-temperature construction in winter, some related technical means such as early strength cement or building a heat preservation shed are adopted in the market, but the means have obvious limitations. The early strength effect of the early strength cement in a deep negative temperature environment is greatly reduced, the strength requirement of quick repair is difficult to meet, and the external heat preservation measures such as building a heat preservation shed are complex in construction flow, large in manpower and material resource investment, so that the construction cost is greatly increased, and the high-efficiency quick repair cannot be realized due to poor adaptability to irregularly-shaped structures or large-area repair projects. In addition, although the related technology refers to part of strength indexes of the negative temperature type repair mortar, key performance parameters such as early compressive strength, interface bonding strength and the like are not disclosed, the early use performance and bonding reliability of the repair mortar in a negative temperature environment are difficult to comprehensively evaluate, and the actual engineering requirements of repairing a concrete structure in a alpine region cannot be fully met. Therefore, the repair mortar which can adapt to the negative temperature environment, realize rapid setting and hardening, has good early-stage compressive strength and interface bonding strength and stably develops middle-stage and later-stage performances is developed, and has great engineering application value, and the repair mortar has urgent technical requirements for guaranteeing safe and stable operation of infrastructure in cold regions and prolonging the whole life cycle of the infrastructure. Disclosure of Invention The invention aims to solve the core technical problems faced by concrete structure repair in a negative temperature environment in a alpine region, namely the problems that cement hydration reaction is obviously inhibited at low temperature, so that the traditional repair mortar is greatly prolonged in setting time, slow in early strength development and even stagnant, and cannot meet the construction requirement of quick repair of an infrastructure, free wa