阅读说明：本技术 一种改性磷酸镁水泥砂浆及其制备方法 (Modified magnesium phosphate cement mortar and preparation method thereof ) 是由 叶艳霞 谢夫林 付翠红 马思敏 景聪 于 2021-11-03 设计创作，主要内容包括：本发明公开了一种改性磷酸镁水泥砂浆,由以下成分组成：氧化镁、磷酸二氢钾、复合缓凝剂、砂子、硅灰以及水,改性磷酸镁水泥砂浆中氧化镁与磷酸二氢钾的摩尔比值为4:1-6:1,复合缓凝剂的加入量为氧化镁和磷酸二氢钾总共质量的3％-10％,硅灰与氧化镁、磷酸二氢钾和硅灰总质量的质量比值为5％-20％,砂子与氧化镁、磷酸盐和硅灰总共质量的质量比值为1:1,氧化镁、磷酸二氢钾、复合缓凝剂、硅灰共同组成胶凝组分,水和胶凝组分的质量比为0.2-0.25。本发明的一种改性磷酸镁水泥砂浆,其流动性较好,具有延缓磷酸镁水泥砂浆凝结时间的效果和改善其后期强度增长率低以及耐水性差的问题。本发明还公开了一种改性磷酸镁水泥砂浆的制备方法。(The invention discloses modified magnesium phosphate cement mortar which comprises the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25. The modified magnesium phosphate cement mortar provided by the invention has good fluidity, and has the effects of delaying the setting time of the magnesium phosphate cement mortar and improving the problems of low later strength increase rate and poor water resistance. The invention also discloses a preparation method of the modified magnesium phosphate cement mortar.)

1. The modified magnesium phosphate cement mortar is characterized by comprising the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25.

2. The modified magnesium phosphate cement mortar of claim 1, wherein the composite retarder is a retarder formed by mixing glucose and boric acid according to a certain proportion.

3. The modified magnesium phosphate cement mortar of claim 2, wherein the mass ratio of the boric acid to the glucose is 3: 5.27.

4. The modified magnesium phosphate cement mortar of any one of claims 1 to 3, wherein the magnesium oxide has a purity of 90% or more and is composed of MgCO₃Is prepared by high-temperature calcination, and the reaction formula isWherein the calcining temperature is more than or equal to 1200 ℃.

5. The modified magnesium phosphate cement mortar of any one of claims 1 to 3, wherein the boric acid is technical grade boric acid and has a purity of 99% or more; the glucose is industrial grade glucose and the purity is more than or equal to 99 percent; the sand is common river sand, and the diameter of the sand is less than or equal to 4 mm.

6. The modified magnesium phosphate cement mortar of any one of claims 1 to 3, wherein the monopotassium phosphate is industrial grade monopotassium phosphate and the purity is not less than 99%.

7. The preparation method of the modified magnesium phosphate cement mortar is characterized by comprising the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to perform low-speed stirring at a rotating speed of 140 +/-5 r/min for 1-3min and at a stirring temperature of 20-30 ℃ in a rotating manner of 62 +/-5 r/min;

step 3, continuously adding the water weighed in the step 1 into a planetary stirrer to slowly stir at the rotating speed of rotation of 140 +/-5 r/min and revolution of 62 +/-5 r/min for 1min at the stirring temperature of 20-30 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly stir at the rotating speed of 285 +/-10 r/min of rotation and 125 +/-10 r/min of revolution for 2-3min at the stirring temperature of 20-30 ℃ to prepare cement mortar.

8. The preparation method of the modified magnesium phosphate cement mortar as claimed in claim 7, wherein the composite retarder is formed by mixing glucose and boric acid according to a mass ratio of 3: 5.27.

Technical Field

The invention belongs to the technical field of building materials, relates to modified magnesium phosphate cement mortar, and further relates to a preparation method of the modified magnesium phosphate cement mortar, wherein the modified magnesium phosphate cement mortar is used for the technical field of structural repair and reinforcement.

Background

The magnesium phosphate cement is a novel material between ceramic and cement, and is an inorganic gelled material which takes phosphate as a binding image and is generated by acid-base chemical reaction and physical action of soluble phosphate, magnesium oxide and an additive according to a certain proportion under an acidic condition. Compared with common Portland cement, the magnesium phosphate cement has the advantages of fast hydration reaction, high early strength, high bonding strength with a repaired material, good wear resistance, volume stability, salt resistance, high temperature resistance and the like. The method has wide application prospect in the aspect of quick repair of projects such as factory building facilities, municipal arterial roads, bridge docks, civil house buildings, airport runways, expressways and the like, and has very important application value and military significance in the aspects of quick construction of national defense projects and military airports and the emergency repair and recovery of engineering facilities.

However, magnesium phosphate cement mortar currently has the following problems: the coagulation speed is high, and the coagulation time is uncontrollable; secondly, the water resistance is poor, and the compressive strength of the waterproof paint is shrunk inversely under the humid and soaked environments; furthermore, the salt corrosion resistance is poor, and the strength of the composite material is reduced to a certain extent in seawater and underground environments. Thus severely limiting its application range.

Disclosure of Invention

The invention aims to provide modified magnesium phosphate cement mortar which has good fluidity, has the effect of delaying the setting time of the magnesium phosphate cement mortar and solves the problems of low later strength increase rate and poor water resistance.

The invention also aims to provide a preparation method of the modified magnesium phosphate cement mortar.

The technical scheme adopted by the invention is that the modified magnesium phosphate cement mortar is composed of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25.

Preferably, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion.

Preferably, the mass ratio of boric acid to glucose is 3: 5.27.

Preferably, the purity of the magnesium oxide is more than or equal to 90 percent and is formed by MgCO₃Is prepared by high-temperature calcination, and the reaction formula isWherein the calcining temperature is more than or equal to 1200 ℃.

Preferably, the boric acid is industrial grade boric acid and the purity is more than or equal to 99 percent; the glucose is industrial grade glucose and the purity is more than or equal to 99 percent; the sand is common river sand, and the diameter of the sand is less than or equal to 4 mm.

Preferably, the monopotassium phosphate is industrial monopotassium phosphate and the purity is more than or equal to 99 percent.

The invention adopts another technical scheme that the preparation method of the modified magnesium phosphate cement mortar is implemented according to the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to perform low-speed stirring at a rotating speed of 140 +/-5 r/min for 1-3min and at a stirring temperature of 20-30 ℃ in a rotating manner of 62 +/-5 r/min;

step 3, continuously adding the water weighed in the step 1 into a planetary stirrer to slowly stir at the rotating speed of rotation of 140 +/-5 r/min and revolution of 62 +/-5 r/min for 1min at the stirring temperature of 20-30 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly stir at the rotating speed of 285 +/-10 r/min of rotation and 125 +/-10 r/min of revolution for 2-3min at the stirring temperature of 20-30 ℃ to prepare cement mortar.

Preferably, the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27.

The invention has the beneficial effects that:

the modified magnesium phosphate cement mortar is prepared by taking magnesium phosphate cement as a cementing material, adopting composite retarder boric acid and glucose for coagulation regulation, taking common river sand as fine aggregate, doping silica fume for modification, and adding mixing water, wherein reasonable doping of the silica fume is guarantee of strength, and excessive doping can deteriorate the performance of the material; the mixing amount of water is the contradiction between the mechanics and the working performance and is uniform;

the hydration of the magnesium phosphate cement is an exothermic reaction based on acid-base neutralization reaction (phosphate and metal oxide), when no retarder is added, the setting time is only about 3 minutes, the setting time cannot be applied to actual engineering, and the early strength of the material is greatly reduced due to excessive addition of the retarder.

The mortar strength test is carried out according to GB17671-1999 method for testing cement mortar strength (ISO method).

The ratio of 3d flexural strength/3 d compressive strength of the modified mortar, namely the flexural ratio, is taken as a measure index of flexibility.

The ratio of 3d, 14d and 28d soaking compressive strength/28 d air curing compressive strength of the modified mortar is 5 percent of NaCl and 5 percent of Na, and the modified mortar is 3d, 14d and 28d respectively₂SO₄The ratio of solution erosion/28 d air curing compressive strength, i.e., the softening coefficient, is used as a measure of water and salt resistance.

The beneficial technical effects of the invention are as follows:

1. the early strength is high: the 3d compressive strength/rupture strength is as high as about 33/12 MPa;

2. the coagulation time is controllable: according to the invention, the composite retarder boric acid, glucose and silica fume are added, and the mortar setting time is controlled by the composite action of the boric acid, the glucose and the silica fume and adjusting the addition ratio of the boric acid, the glucose and the silica fume.

3. The strength is improved: the silica fume is added to effectively improve the microstructure of a hardened body of the potassium magnesium phosphate cement-based component, and can play a role in grading a cementing material to improve the compactness of the material, so that the overall strength of the magnesium phosphate cement mortar is improved, the 28-day flexural strength of the magnesium phosphate cement mortar is improved by 33.66 percent, and the 28-day compressive strength of the magnesium phosphate cement mortar is improved by 14.17 percent. The 3d folding ratio is reduced by about 14.6 percent, and the flexibility of the material is better improved.

4. Green and environment-friendly: the mineral admixture has wide source, is taken from industrial waste needing additional treatment, can fully utilize the industrial waste, enlarges the use range of the industrial waste and is environment-friendly.

5. Improvement of water resistance and salt resistance: the silica fume contains a large amount of active silica and alumina, and aluminosilicate reaction occurs in the magnesium phosphate cement repair mortar to generate magnesium aluminosilicate gel, so that on one hand, the magnesium aluminosilicate gel has good water resistance and chemical stability, and is used for blocking partial intercommunicating pores in the matrix, improving the internal pore structure of the magnesium phosphate cement repair mortar, and improving the water resistance and salt corrosion resistance of the material; on the other handThe magnesium aluminosilicate gel serves as a framework in the magnesium phosphate cement to play a role in inhibiting deformation of other hydration products, the 28-day water resistance softening coefficient is 77.18, the NaCl solution resistance softening coefficient is 109.17, the Na resistance is improved by 33.28 percent compared with that of the non-doped silica fume, and the Na resistance is realized₂SO₄The solution softening coefficient is larger than that of the solution without doping the silica fume in the same soaking age, and the solution shows better water resistance and salt corrosion resistance.

Drawings

FIG. 1 is a composition diagram of a modified magnesium phosphate cement mortar.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to modified magnesium phosphate cement mortar, which is shown in figure 1 and comprises the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25; wherein the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27; the purity of the magnesium oxide is more than or equal to 90 percent and is formed by MgCO₃Is prepared by high-temperature calcination, and the reaction formula isWherein the calcining temperature is more than or equal to 1200 ℃; the boric acid is industrial grade boric acid and the purity is more than or equal to 99 percent; the glucose is industrial grade glucose and the purity is more than or equal to 99 percent; the sand is common river sand, and the diameter of the sand is less than or equal to 4 mm; the potassium dihydrogen phosphate is industrial-grade potassium dihydrogen phosphate and has a purity of more than or equal to 99%.

The invention relates to a preparation method of modified magnesium phosphate cement mortar, which is implemented according to the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1-6:1, the addition amount of the composite retarder is 3% -10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5% -20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2-0.25; the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to perform low-speed stirring at a rotating speed of 140 +/-5 r/min for 1-3min and at a stirring temperature of 20-30 ℃ in a rotating manner of 62 +/-5 r/min;

step 3, continuously adding the water weighed in the step 1 into a planetary stirrer to slowly stir at the rotating speed of rotation of 140 +/-5 r/min and revolution of 62 +/-5 r/min for 1min at the stirring temperature of 20-30 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly stir at the rotating speed of 285 +/-10 r/min of rotation and 125 +/-10 r/min of revolution for 2-3min at the stirring temperature of 20-30 ℃ to prepare cement mortar.

Example 1

The embodiment provides modified magnesium phosphate cement mortar and a preparation method thereof, wherein the magnesium phosphate cement mortar comprises the following components in parts by weight:

45g of silica fume, 545.74g of magnesium oxide, 309.26g of monopotassium phosphate, 9.31g of boric acid, 16.34g of glucose, 900g of sand and 180g of water;

in the embodiment, the glue-sand ratio is 1:1, the water-glue ratio is 0.20:1, the fine aggregate is continuous graded common river sand with the grain size less than or equal to 4mm, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate in the magnesium phosphate cement is 6: 1; the addition amount of the composite retarder is 3 percent of the total mass of magnesium oxide and phosphate, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion, wherein m (boric acid): m (glucose) ═ 3: 5.27. m silica fume: m (silica fume + magnesium oxide + potassium dihydrogen phosphate) is 5%;

the preparation method of the modified magnesium phosphate cement mortar comprises the following steps:

s1, preparing materials: mixing the materials according to the weight;

s2, adding the composite retarder, the acid component phosphate and the sand into a planetary mixer to perform slow mixing at a rotation speed of 140r/min and a revolution speed of 62r/min for 2min at a mixing temperature of 25 ℃;

s3, adding water, slowly stirring at a rotation speed of 140r/min for 1min and a revolution speed of 62r/min at a stirring temperature of 20-30 ℃;

s4, adding magnesium oxide and silica fume into a planetary mixer to rapidly mix at a rotation speed of 285r/min and 125r/min in a revolution manner, wherein the mixing time is 2min, and the mixing temperature is 25 ℃ to prepare cement mortar;

s5, forming: pouring, vibrating and curing the cement mortar to form the cement mortar.

Example 2

The embodiment provides modified magnesium phosphate cement mortar and a preparation method thereof, wherein the modified magnesium phosphate cement mortar comprises the following components in parts by weight:

the weight of the silica fume is 90g, the weight of the magnesium oxide is 517.02g, the weight of the potassium dihydrogen phosphate is 292.98g, the weight of the boric acid is 8.82g, the weight of the glucose is 15.48g, the weight of the sand is 900g, and the weight of the water is 180 g.

In the embodiment, the glue-sand ratio is 1:1, the water-glue ratio is 0.20:1, the fine aggregate is continuous graded common river sand with the grain size less than or equal to 4mm, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate in the magnesium phosphate cement is 6: 1; the addition amount of the composite retarder is 3 percent of the total mass of magnesium oxide and phosphate, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion, wherein m (boric acid): m (glucose) ═ 3:5.27, m silica fume: m (silica fume + magnesium oxide + potassium dihydrogen phosphate) ═ 10%.

The preparation method is as in example 1.

Example 3

The embodiment provides modified magnesium phosphate cement mortar and a preparation method thereof, wherein the modified magnesium phosphate cement mortar comprises the following components in parts by weight:

135g of silica fume, 488.30g of magnesium oxide, 276.70g of monopotassium phosphate, 8.33g of boric acid, 14.62g of glucose, 900g of sand and 180g of water.

In the embodiment, the glue-sand ratio is 1:1, the water-glue ratio is 0.20:1, the fine aggregate is continuous graded common river sand with the grain size less than or equal to 4mm, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate in the magnesium phosphate cement is 6: 1; the addition amount of the composite retarder is 3 percent of the total mass of magnesium oxide and phosphate, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion, wherein m (boric acid): m (glucose) ═ 3:5.27, m silica fume: m (silica fume + magnesium oxide + potassium dihydrogen phosphate) ═ 15%.

The preparation method is as in example 1.

Example 4

The embodiment provides modified magnesium phosphate cement mortar and a preparation method thereof, wherein the modified magnesium phosphate cement mortar comprises the following components in parts by weight:

180g of silica fume, 459.57g of magnesium oxide, 260.43g of monopotassium phosphate, 7.84g of boric acid, 13.76g of glucose, 900g of sand and 180g of water.

In the embodiment, the glue-sand ratio is 1:1, the water-glue ratio is 0.20:1, the fine aggregate is continuous graded common river sand with the grain size less than or equal to 4mm, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate in the magnesium phosphate cement is 6: 1; the addition amount of the composite retarder is 3 percent of the total mass of magnesium oxide and phosphate, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion, wherein m (boric acid): m (glucose) ═ 3:5.27, m silica fume: m (silica fume + magnesium oxide + potassium dihydrogen phosphate) ═ 20%.

The preparation method is as in example 1.

Example 5

The embodiment provides modified magnesium phosphate cement mortar and a preparation method thereof, wherein the modified magnesium phosphate cement mortar comprises the following components in parts by weight:

the weight of the silica fume is 0g, the magnesium oxide is 574.47g, the potassium dihydrogen phosphate is 325.53g, the boric acid is 9.80g, the glucose is 17.20g, the sand is 900g, and the water is 180 g.

In the embodiment, the glue-sand ratio is 1:1, the water-glue ratio is 0.20:1, the fine aggregate is continuous graded common river sand with the grain size less than or equal to 4mm, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate in the magnesium phosphate cement is 6: 1; the addition amount of the composite retarder is 3 percent of the total mass of magnesium oxide and phosphate, the composite retarder is formed by mixing glucose and boric acid according to a certain proportion, wherein m (boric acid): m (glucose) ═ 3:5.27, m silica fume: m (silica fume + magnesium oxide + potassium dihydrogen phosphate) ═ 0%.

The preparation method is as in example 1.

The performance of the modified magnesium phosphate cement mortar obtained in the embodiment is detected, and the specific detection contents are as follows:

1. and (3) testing the strength: the modified magnesium phosphate cement mortar obtained in the example is respectively pressed and molded to prepare test pieces, the size of each test piece is 40mm x 160mm, the test pieces are demoulded within 3 hours to 1 day, and the test pieces are cured for 3d and 28d in an indoor natural environment to test the compressive strength, the flexural strength and the flexural ratio, wherein the curing temperature is 20-30 ℃, and is shown in the table I.

2. Water resistance: respectively soaking the test pieces of the embodiment 3 and the embodiment 5 which are naturally cured for 28 days in water for 3d, 14d and 28 d; salt resistance: the test pieces of example 3 and example 5 after being naturally cured for 28 days were placed in a 5% NaCl solution and 5% Na solution, respectively₂SO₄The solution is corroded for 3d, 14d and 28d respectively, and the compressive strength and the softening coefficient of the solution are tested. The results are shown in Table II.

Watch 1

Watch two

As can be seen from the table above, the modified magnesium phosphate cement mortar of the invention has better working performance, high matrix strength, water resistance and better salt resistance. The preparation method of the magnesium phosphate cement-based pavement patching material is simple in process, stable in quality, low in requirement on the external environment and suitable for mass production and preparation during construction.

Example 6

A preparation method of modified magnesium phosphate cement mortar is implemented according to the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 4:1, the addition amount of the composite retarder is 3% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 5%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.2; the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to slowly stir at a rotating speed of 135r/min of rotation and 57r/min of revolution, wherein the stirring time is 1min, and the stirring temperature is 20 ℃;

step 3, continuously adding the water weighed in the step 1 into a planetary stirrer to slowly stir at the rotating speed of 135r/min autorotation and 57r/min revolution, wherein the stirring time is 1min, and the stirring temperature is 20 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly mix at a rotating speed of 275r/min rotation and 115r/min revolution for 2min at a mixing temperature of 20 ℃ to prepare the cement mortar.

Example 7

A preparation method of modified magnesium phosphate cement mortar is implemented according to the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 5:1, the addition amount of the composite retarder is 6% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 15%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.22; the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to perform slow mixing at a rotating speed of 140r/min for rotation and 62r/min for revolution, wherein the mixing time is 2min, and the mixing temperature is 25 ℃;

step 3, taking the water weighed in the step 1, continuously adding the water into a planetary stirrer to slowly stir at the rotating speed of 140r/min for rotation and 62r/min for revolution, wherein the stirring time is 1min, and the stirring temperature is 25 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly mix at the rotation speed of 285r/min and the revolution speed of 125r/min, wherein the mixing time is 2min, and the mixing temperature is 25 ℃ to prepare the cement mortar.

Example 8

A preparation method of modified magnesium phosphate cement mortar is implemented according to the following steps:

step 1, weighing the following ingredients according to mass percentage

The modified magnesium phosphate cement mortar consists of the following components: the modified magnesium phosphate cement mortar comprises magnesium oxide, monopotassium phosphate, a composite retarder, sand, silica fume and water, wherein the molar ratio of the magnesium oxide to the monopotassium phosphate in the modified magnesium phosphate cement mortar is 6:1, the addition amount of the composite retarder is 10% of the total mass of the magnesium oxide and the monopotassium phosphate, the mass ratio of the silica fume to the total mass of the magnesium oxide, the monopotassium phosphate and the silica fume is 20%, the mass ratio of the sand to the total mass of the magnesium oxide, the phosphate and the silica fume is 1:1, the magnesium oxide, the monopotassium phosphate, the composite retarder and the silica fume jointly form a gelling component, and the mass ratio of the water to the gelling component is 0.25; the composite retarder is formed by mixing glucose and boric acid according to the mass ratio of 3: 5.27;

step 2, adding the compound retarder, the potassium dihydrogen phosphate and the sand weighed in the step 1 into a planetary mixer to slowly stir at the rotating speed of rotation of 145r/min and revolution of 67r/min for 3min at the stirring temperature of 30 ℃;

step 3, continuously adding the water weighed in the step 1 into a planetary stirrer to slowly stir at the rotating speed of rotation of 145r/min and revolution of 67r/min for 1min at the stirring temperature of 30 ℃;

and 4, continuously adding the magnesium oxide and the silica fume weighed in the step 1 into a planetary mixer to rapidly mix at the rotation speed of 295r/min and the revolution speed of 135r/min, wherein the mixing time is 3min, and the mixing temperature is 30 ℃ to prepare the cement mortar.