CN-121990811-A - Fiber-reinforced magnesium phosphate cement with setting time capable of being regulated and controlled in large range and preparation method thereof

Abstract

The invention relates to fiber reinforced magnesium phosphate cement with widely adjustable setting time and a preparation method thereof, belonging to the technical field of preparation of building raw materials. The cement comprises, by weight, 35-55 parts of modified magnesium oxide, 20-35 parts of acid phosphate, 5-10 parts of retarder, 15-30 parts of mineral admixture, 2-5 parts of high-molecular water reducer, 0.5-2.5 parts of modified carbon fiber and 8-16 parts of water. The invention also provides a preparation method of the magnesium phosphate cement. According to the invention, the magnesia and the alumina are subjected to solid-phase reaction at high temperature, a layer of magnesia-alumina spinel is grown on the surface of the magnesia to serve as an isolation layer, so that the surface of the magnesia is modified, and meanwhile, the temperature, the time and the raw material consumption in the solid-phase reaction process can be controlled, so that the setting time of the magnesium phosphate cement can be regulated and controlled within 20-135 min. The cement has the advantages of high early strength, quick strength development, high bonding strength, good volume stability, convenience in construction and the like.

Inventors

• ZHOU XUEBIN
• ZHANG XIAO
• TIAN DONG
• WANG TIANQI
• MA CHAOQUN
• SUN SHASHA
• XU HANWEN

Assignees

• 潍坊水动能科技产业研究院

Dates

Publication Date

20260508

Application Date

20241101

Claims (9)

1. 1. The fiber reinforced magnesium phosphate cement with the setting time capable of being regulated and controlled in a large range is characterized by comprising, by weight, 35-55 parts of modified magnesium oxide, 20-35 parts of acid phosphate, 3-6 parts of retarder, 15-30 parts of mineral admixture, 2-5 parts of high-molecular water reducer, 0.5-2.5 parts of modified carbon fiber and 8-16 parts of water.
2. 2. The fiber reinforced magnesium phosphate cement with the setting time capable of being controlled in a large range is characterized by being prepared from 92-96 parts by weight of magnesium oxide, 3-6 parts by weight of aluminum oxide and 1-2 parts by weight of titanium dioxide, wherein the modified magnesium oxide is prepared by calcining at 1150-1550 ℃ at a temperature rising speed of 5-8 ℃ per minute, crushing, ball milling and screening, and the magnesium oxide is one or more of light-burned magnesium, heavy-burned magnesium and electric-burned magnesium, and has a fineness of 325-800 meshes.
3. 3. The fiber-reinforced magnesium phosphate cement with widely adjustable setting time according to claim 1, wherein the acid phosphate is composed of one or two of potassium dihydrogen phosphate and ammonium dihydrogen phosphate.
4. 4. The fiber reinforced magnesium phosphate cement with widely adjustable setting time according to claim 1, wherein the retarder is composed of one or more of borax, anhydrous boric acid, and tartaric acid.
5. 5. The fiber reinforced magnesium phosphate cement with widely adjustable setting time according to claim 1, wherein the mineral admixture is composed of one or more of fly ash, metakaolin, silica fume, slag.
6. 6. The fiber-reinforced magnesium phosphate cement with widely adjustable setting time according to claim 1, wherein the high molecular water reducing agent is MelmentF sulfonated melamine polycondensate powder produced by basf, germany.
7. 7. The fiber reinforced magnesium phosphate cement with the setting time capable of being controlled in a large range according to claim 1, wherein the modified carbon fiber is obtained by immersing and etching carbon fiber with nitric acid, washing with water and drying, the mass fraction of the nitric acid is 34% -68%, and the length of the carbon fiber is 3-12mm.
8. 8. The fiber-reinforced magnesium phosphate cement with widely adjustable setting time according to claim 1, wherein the carbon fiber is a 12k chopped carbon fiber with a monofilament diameter of 7.3 μm.
9. 9. The method for preparing fiber-reinforced magnesium phosphate cement with widely adjustable setting time according to any one of claims 1 to 8, comprising the steps of: ① The preparation of the modified magnesium oxide comprises the steps of calcining 92-96 parts of magnesium oxide, 3-6 parts of aluminum oxide and 1-2 parts of titanium dioxide at a high temperature of 1300-1500 ℃, and crushing, ball milling and screening to obtain the modified magnesium oxide; ② Preparing modified carbon fiber, namely soaking and etching the carbon fiber by nitric acid, washing by water and drying to obtain the modified carbon fiber; ③ Mixing 35-55 parts of modified magnesium oxide, 20-35 parts of acid phosphate, 3-6 parts of retarder, 15-30 parts of mineral admixture, 2-5 parts of high molecular water reducer and 0.5-2.5 parts of modified carbon fiber to prepare magnesium phosphate cement dry powder; ④ And adding 8-16 parts of water into the prepared magnesium phosphate cement dry powder, stirring, injecting into a mould, vibrating, naturally solidifying, and demoulding to obtain the fiber reinforced magnesium phosphate cement.

Description

Fiber-reinforced magnesium phosphate cement with setting time capable of being regulated and controlled in large range and preparation method thereof The invention relates to fiber reinforced magnesium phosphate cement with widely adjustable setting time and a preparation method thereof, belonging to the technical field of preparation of building raw materials. Background Magnesium phosphate cement is an inorganic cementing material obtained by acid-base neutralization reaction of magnesium oxide and soluble phosphate, and is also called as chemical bonding ceramic. The magnesium phosphate cement has the advantages of quick hardening, early strength, good fluidity, high bonding strength with repaired materials, good wear resistance, good volume stability and the like, so that the magnesium phosphate cement has wide development and application prospects in the field of quick repair of concrete pavements and concrete structures, and has very important military significance in the aspects of quick construction and repair of national defense engineering and military airports. However, the magnesium phosphate cement also has some problems in the concrete use process, particularly problems of difficult construction caused by poor controllability of setting time and over-high setting speed, large heat release amount of hydration reaction and the like. On the premise of not taking any retarding measures, the hydration reaction speed of the magnesium phosphate cement is high, the setting time is extremely short, and often only a few minutes are needed, and the operation time required by construction is not completely met, so that great difficulty exists in the construction process. In addition, the boron element remained in the hydration product can diffuse into the environment, and even can be dissolved into the groundwater along with rainwater, so that the environment and the physical health of people are greatly damaged. In order to facilitate construction, the setting time of magnesium phosphate cement must be prolonged, and the current mainstream method is to directly add borax, boric acid and the like into magnesium phosphate cement as retarder. The direct addition of a large amount of boron-containing retarder can cause the early strength of the magnesium phosphate cement to develop too slowly, and the final strength is greatly affected. For example, patent CN108069692a describes a magnesium phosphate cement grouting material for quick repair, using boric acid as a main retarder, the setting time can be controlled in a small range, but the early fracture resistance and compression resistance are extremely low and the later strength is also greatly affected due to the use of a large amount of boric acid. Thus, a new approach may be sought as a primary retarder, with no or reduced use of boron-containing retarders. Therefore, the early strength of the magnesium phosphate cement can be ensured to be developed, the final strength is not influenced, and the sufficient construction time of the magnesium phosphate cement can be ensured, so that the method has extremely important significance for the application of the magnesium phosphate cement. For example, patent CN115724643a describes a high refractory magnesium phosphate cement-based material with controllable hydration reaction, and by carbonating sintered magnesium oxide powder, a compact layer containing hydration products such as basic magnesium carbonate is formed on the surface of sintered magnesium oxide particles, so that the problem of too fast setting time of the magnesium phosphate cement-based material is solved, but the setting time is still short, the early strength is too low, the preparation process is complex, and the application of the material is restricted. Although the method can prolong the setting time of the magnesium phosphate cement to a certain extent, the prolonged time is limited, the early strength can be greatly and negatively influenced, the later strength is poor, and most importantly, the setting time cannot be regulated according to specific construction conditions. Aiming at the problems, the invention provides fiber reinforced magnesium phosphate cement with widely adjustable setting time and a preparation method thereof. Disclosure of Invention Aiming at the defects and shortcomings of the existing magnesium phosphate cement and in combination with the requirements of specific construction conditions, the invention provides the fiber reinforced magnesium phosphate cement with widely adjustable setting time and the preparation method thereof, and the magnesium aluminate spinel is innovatively grown on the surface of magnesium oxide as an isolation layer through solid phase reaction of magnesium oxide and aluminum oxide at high temperature. The barrier layer may hinder the contact and reaction between the magnesium oxide and the acid phosphate, slowing down the cement hydration rate and allowing slow accumulation of hydration