CN113651564A - Modified waterproof anti-crack cement mortar and preparation method thereof - Google Patents

Abstract

The application relates to the technical field of building materials, and particularly discloses modified waterproof anti-cracking cement mortar and a preparation method thereof. The mortar is prepared from the following raw materials in parts by weight: 30-42 parts of cement, 155 parts of sand, 172 parts of water, 15-22 parts of modified organosilicon waterproofing agent, 0.1-1.5 parts of polypropylene fiber, 5-13 parts of rubber powder and 1-3 parts of additive. The mortar has good waterproof performance and crack resistance. The waterproof anti-cracking cement mortar and the inorganic heat insulation material are combined to form a waterproof heat insulation system, the waterproof heat insulation system can give consideration to both waterproof and anti-cracking functions, the quality problems of cracking, water seepage, hollowing, falling and the like of the outer wall of the building heat insulation project can be effectively solved, and the safety of the heat insulation system is improved.

Description

Modified waterproof anti-crack cement mortar and preparation method thereof

Technical Field

The application relates to the technical field of building materials, in particular to modified waterproof anti-cracking cement mortar and a preparation method thereof.

Background

With the development of building forms and the improvement of the taste of building structures, the concept of wall heat preservation and energy conservation gradually deepens into the heart, an external wall heat preservation and energy conservation system becomes the mainstream of the wall heat preservation form due to numerous advantages, and the heat preservation materials which can be selected at present mainly comprise inorganic materials such as heat preservation mortar, foamed cement boards, rock wool boards and the like. However, the inorganic material has strong water absorption, once the heat insulation material absorbs water, various performances of the heat insulation material are deteriorated, the heat insulation effect is greatly reduced, and meanwhile, the heat insulation and decoration engineering of the outer facade of the building can generate quality problems of cracking, water seepage, hollowing, falling and the like in different degrees, so that the appearance and the energy-saving effect of the building are seriously damaged, and the service life of the building is greatly reduced.

Therefore, in the external thermal insulation system of the external wall, the anti-cracking waterproof protective layer has to play a good role in protecting the thermal insulation layer, and thus, the indexes of the anti-cracking waterproof mortar, such as impermeability and water permeability, are improved. However, the mortar of the prior art is generally prepared by mixing an inorganic cementitious material with fine aggregates and water in proportion, and is also called mortar. The waterproof and anti-cracking performance of the mortar does not meet the requirement, so the development of the waterproof and anti-cracking mortar is urgently needed.

Disclosure of Invention

The application provides modified waterproof anti-crack cement mortar and a preparation method thereof.

In a first aspect, the application provides a modified waterproof anti-crack cement mortar, which adopts the following technical scheme:

the modified waterproof anti-crack cement mortar is prepared from the following raw materials in parts by weight:

30-42 parts of cement, 155 parts of sand, 172 parts of water, 15-22 parts of modified organosilicon waterproofing agent, 0.1-1.5 parts of polypropylene fiber, 5-13 parts of rubber powder and 1-3 parts of additive.

By adopting the technical scheme, the organosilicon waterproofing agent, the cement and the rubber powder are uniformly dispersed in a cement mortar system in the process of adding water and stirring, and then a latex network structure taking the cement as a continuous medium is formed in the hardening process, so that the network structure can effectively prevent moisture from permeating on one hand, and further achieves the purposes of waterproofing and moistureproof, and on the other hand, the polypropylene fiber is fused with the network structure, so that the toughness and the strength of the mortar system can be increased, the tensile strength and the shearing resistance of the mortar are enhanced, and further the anti-cracking performance of the mortar can be enhanced. In addition, the organosilicon waterproofing agent has good mixing property with various raw materials of mortar, and reacts with cement to form a siloxane chain, and finally a stable reticular siloxane hydrophobic layer is formed, so that the long-term waterproof function is maintained; the tensile bonding strength of the mortar can be improved, cracks generated by shrinkage in the cement curing process are reduced, and the cracking is favorably reduced.

Preferably, the water-cement ratio is 42-58%.

The water cement ratio, also called water cement ratio, refers to the weight ratio of the amount of water in the concrete to the amount of cement. The water-cement ratio is too small, the fluidity of mortar is poor, pumping is affected, and construction is not facilitated; the water-cement ratio is too large, which can improve the fluidity of the mortar, but also easily cause the mortar to separate and bleed, influence the workability of the mortar and further influence the strength of the mortar. In the application, the water-cement ratio of the mortar is controlled to be 42-58%, so that the basic mechanical property of the mortar is not damaged while the good construction performance of the mortar is ensured.

Preferably, the modified silicone waterproofing agent is any one selected from the group consisting of modified silicone waterproofing agent P750, modified silicone waterproofing agent P730, and modified silicone waterproofing agent WR 2.

The modified organosilicon waterproofing agent can reduce the loss of free moisture in the mortar, reduce the dry shrinkage rate of the mortar and improve the capability of the mortar for resisting the external environment change, thereby improving the waterproofing performance and the crack resistance of the mortar. Any one or more of a modified organosilicon waterproofing agent P750, a modified organosilicon waterproofing agent P730 and a modified organosilicon waterproofing agent WR2 are added into the mortar, the waterproof performance of the mortar is improved in different degrees, the setting and hardening time of the mortar can be delayed, and the mechanical property of the mortar is basically not influenced. The inventor finds that when the modified organosilicon waterproofing agent P750 or the modified organosilicon waterproofing agent WR2 is doped into the mortar, the mortar has better waterproof performance and mechanical property, particularly low water absorption rate and good water resistance; and the modified organosilicon waterproofing agent P730 is added into the mortar, and although the waterproofing performance is inferior to that of P750 and WR2, the mechanical property is better. Therefore, for mortar with high water resistance, the modified organosilicon waterproofing agent P750 or the modified organosilicon waterproofing agent WR2 is preferably selected; and when the requirements on both waterproofness and mechanical properties are higher, the modified organosilicon waterproofing agent P730 is preferably selected. In the present application, the modified silicone waterproofing agent P730 is preferably selected in order to obtain a mortar having both water repellency and crack resistance.

Preferably, the rubber powder is at least one selected from dispersible latex powder, asphalt modified rubber powder and rubber powder 8031H.

The waterproof performance and the bonding performance of the mortar can be enhanced by doping the dispersible latex powder into the mortar; the asphalt modified rubber powder is doped into the mortar, so that the mortar has excellent waterproof performance, but the strength of the mortar is influenced; the 8031H rubber powder is doped into the mortar, so that the bonding strength of the mortar can be enhanced, and the water absorption of the mortar is reduced. The inventor finds that the waterproof performance and the bonding strength of the mortar are improved most remarkably when the dispersible latex powder and the 8031H rubber powder are matched, and preferably, the weight ratio of the dispersible latex powder to the 8031H rubber powder is (0.3-0.7): 2; optimally, the weight ratio of the dispersible latex powder to the rubber powder 8031H is 0.62: 2.

Preferably, the admixture comprises an expanding agent, a water reducing agent and a water retaining agent; more preferably, the weight ratio of the expanding agent to the water reducing agent to the water retaining agent is (0.1-0.5): 1: (0.1-0.3).

The additive is an additive added to cement and sand to improve the properties of cement mortar. In the application, the expanding agent can be a magnesium oxide expanding agent, the water reducing agent can be a slump-retaining water reducing agent, and the water retaining agent can be hydroxypropyl methyl cellulose ether, which are mixed according to a specific proportion, so that mortar drying shrinkage cracks can be reduced, and the crack resistance and the impermeability of the mortar are improved; the early strength of the mortar is developed quickly, the shrinkage of the mortar can be effectively compensated, and the long-term strength is stably increased; in addition, the alkali aggregate reaction can be inhibited, and the corrosion to the steel bar is reduced. The additive is added into the mortar, so that the problems of hollowing, cracking and the like of the mortar can be well solved.

Preferably, the sand comprises machine-made sand and natural sand; further preferably, the weight ratio of the machine-made sand to the natural sand is (0.3-0.7) to 1; still more preferably, the machine-made sand has a particle size of 0.1 to 0.5 mm.

By using the formula of the application, natural sand can be replaced by partial machine-made sand on the premise of not influencing the basic performance of the mortar, so that the exploitation of the natural sand can be reduced, and the environment is protected. In addition, natural sand is replaced by partial machine-made sand, so that the daily requirement of the mortar industry on the sand can be met, and the cost can be reduced to a certain extent.

The strength of the mortar is affected by the ratio of the machine-made sand to the natural sand which is too small or too large, so that the weight ratio of the machine-made sand to the natural sand is (0.3-0.7):1 to ensure the strength and the cost of the mortar.

The waterproof anti-cracking cement mortar and the inorganic heat insulation material are combined to form a waterproof heat insulation system, the waterproof heat insulation system can give consideration to both waterproof and anti-cracking functions, the quality problems of cracking, water seepage, hollowing, falling and the like of the outer wall of the building heat insulation project can be effectively solved, and the safety of the heat insulation system is improved.

In a second aspect, the application provides a preparation method of the modified waterproof anti-cracking cement mortar, which adopts the following technical scheme:

a preparation method of modified waterproof anti-crack cement mortar comprises the following preparation steps:

uniformly mixing cement, sand, polypropylene fiber and rubber powder to obtain a dry mixture;

adding the modified organic silicon waterproof agent and the additive into water, and uniformly mixing to obtain a mixed solution;

and uniformly mixing the dry mixture and the mixed solution to obtain the mortar.

In summary, the present application has the following beneficial effects:

the mortar has good waterproof performance, crack resistance and compressive strength; the waterproof anti-cracking cement mortar and the inorganic heat insulation material are combined to form a waterproof heat insulation system, the waterproof heat insulation system can give consideration to both waterproof and anti-cracking functions, the quality problems of cracking, water seepage, hollowing, falling and the like of the outer wall of the building heat insulation project can be effectively solved, and the safety of the heat insulation system is improved.

Detailed Description

The present application will be described in further detail with reference to examples. Specifically, the following are described: the following examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer; the starting materials used in the following examples are all those conventionally commercially available except where specifically noted.

The raw materials used in the examples are specifically as follows:

basic indexes of machine-made sand: bulk density 1590kg/m³Apparent density 2640kg/m³5.7 percent of stone powder, 37 percent of porosity, 4.9 percent of specific particle size and 0.1-0.5mm of particle size;

basic indexes of natural sand: the mud content is 1.6 percent, and the mud block content is 0.15 percent;

water reducing agent: the collapse-retaining polycarboxylate superplasticizer has the water reduction rate of 30 percent and the solid content of 45 percent;

water-retaining agent: hydroxypropyl methyl cellulose ether with viscosity of 100000 mPa.s;

swelling agent: a magnesium oxide expanding agent, wherein the content of magnesium oxide is 61.12%;

cement: general purpose portland cement;

asphalt modified rubber powder: asphalt modified rubber powder K produced by Tianjin Tianying novel building materials Co.

Example 1

A modified waterproof anti-crack cement mortar is prepared as follows:

uniformly mixing 3g of cement, 17.2kg of sand, 2.25kg of polypropylene fiber and 1kg of dispersible milk to obtain a dry mixture;

adding 0.15kg of modified organosilicon waterproofing agent P750 and 0.2kg of collapse-proof polycarboxylic acid water reducing agent into 2.2kg of water, and uniformly mixing to obtain a mixed solution;

and uniformly mixing the dry mixture and the mixed solution to obtain the mortar.

Example 2

A modified waterproof anti-crack cement mortar is prepared as follows:

uniformly mixing 4.2g of cement, 15.5kg of sand, 0.05kg of polypropylene fiber and 0.5kg of dispersible milk to obtain a dry mixture;

adding 0.01kg of modified organosilicon waterproofing agent P750 and 0.1kg of collapse-proof polycarboxylic acid water reducing agent into 1.5kg of water, and uniformly mixing to obtain a mixed solution;

and uniformly mixing the dry mixture and the mixed solution to obtain the mortar.

Example 3

A modified waterproof anti-crack cement mortar is prepared as follows:

uniformly mixing 3.7g of cement, 16.24kg of sand, 0.17kg of polypropylene fiber and 1.3kg of dispersible milk to obtain a dry mixture; adding 0.05kg of modified organosilicon waterproofing agent P750 and 0.3kg of collapse-proof polycarboxylic acid water reducing agent into 1.9kg of water, and uniformly mixing to obtain a mixed solution;

and uniformly mixing the dry mixture and the mixed solution to obtain the mortar.

Examples 4 to 8

Examples 4-8 differ from example 3 only in that: the selection and amount of the rubber powder varied, and the specific formulation of the rubber powder in examples 4-8 is shown in Table 1 below.

TABLE 1 formulation of the rubber powders in examples 4-8

Examples 9 to 11

Examples 9-11 differ from example 7 only in that: the selection and amount of the modified silicone waterproofing agent were varied, and the specific formulation of the modified silicone waterproofing agent in examples 9 to 11 is shown in table 2 below.

TABLE 2 proportioning tables of modified organosilicon waterproofing agents in examples 9 to 11

Examples 12 to 14

Examples 12-14 differ from example 11 only in that: the selection and amount of additives were varied, and the specific formulations of the additives in examples 12-14 are shown in Table 3 below.

TABLE 3 proportioning tables for modified organosilicon waterproofing agents in examples 12 to 14

Examples 15 to 17

Examples 15-17 differ from example 14 only in that: the selection and the amount of the sand are different, and the mixture ratio of the sand in the examples 15 to 17 is specifically shown in the following table 4.

TABLE 4 Sand proportioning tables for examples 15-17

Comparative example

Comparative example 1

Comparative example 1 differs from example 7 only in that no latex powder, i.e. no dispersible latex powder and no latex powder 8031H, was added in comparative example 1, the remainder remaining the same as in example 7.

Comparative example 2

Comparative example 2 differs from example 16 only in that comparative example 2 does not have the modified silicone waterproofing agent added, i.e., no modified silicone waterproofing agent P730 added, and the remainder remains the same as example 16.

Performance test

The basic performances of the mortars prepared in the examples 1-17 and the preparation examples 1-2 of the application are detected according to the national standard GB/T25181-.

The mortar of examples 1-17 and comparative examples 1-2 were tested for crack index (mm) using JC/T951-2005 method for testing crack resistance in cement mortar.

TABLE 5

Mortar sample	Water retention rate/%)	14 days tensile bond Strength/MPa	28 day impermeability grade	Crack index/mm
					Example 1	83	0.425	P6	195
Example 2	72	0.445	P6	191
					Example 3	88	0.465	P8	188
Example 4	89	0.468	P8	187
					Example 5	88	0.525	P8	188
Example 6	90	0.545	P8	183
					Example 7	92	0.561	P8	182
Example 8	91	0.508	P8	185
					Example 9	90	0.558	P8	182
Example 10	92	0.514	P8	186
					Example 11	91	0.569	P8	181
Example 12	93	0.586	P10	181
					Example 13	94	0.591	P10	180
Example 14	90	0.571	P8	183
					Example 15	89	0.575	P8	188
Example 16	91	0.568	P8	185
					Example 17	85	0.542	P8	188
Comparative example 1	69	0.324	P6	223
					Comparative example 2	62	0.358	P6	198

It can be seen by combining examples 1-3 and table 5 that too high or too low water cement ratio of the mortar affects the waterproof performance and crack resistance of the mortar, and when the water cement ratio of the mortar is 42% -58%, the waterproof performance and crack resistance of the mortar are good.

By combining the examples 3-8 and the comparative example 1 and combining the table 5, it can be seen that the addition of the rubber powder and the proportion of the rubber powder both affect the performance of the mortar; compared with the matching use of various rubber powder, the matching use of various rubber powder can improve the waterproof performance of the mortar; in the formula of the application, the dispersible latex powder and the rubber powder 8031H are (0.3-0.7) in weight ratio: 2, the waterproof property and the crack resistance of the mortar are better.

By combining examples 7, 9-10 and comparative example 2 with Table 5, it can be seen that the addition and selection of the modified silicone waterproofing agent both affect the performance of the mortar; the modified organosilicon waterproofing agent P750 or WR2 is added into the mortar, so that the mortar has better waterproof performance but slightly poor mechanical performance; and the modified organosilicon waterproofing agent P730 is added into the mortar, and although the waterproofing performance is inferior to that of P750 and WR2, the mechanical property is better.

As can be seen by combining examples 11 to 13 and Table 5, the swelling agent, the water reducing agent and the water retaining agent are (0.1 to 0.5) by weight: 1: (0.1-0.3) can improve the waterproof performance and the resistance performance of the mortar.

It can be seen from the combination of examples 14-17 and table 5 that, by using the formulation of the present application, the natural sand can be replaced by the partial machine-made sand without affecting the basic performance of the mortar, and specifically, the basic performance of the mortar is not affected when the weight ratio of the machine-made sand to the natural sand in the sand used in the mortar is (0.3-0.7): 1.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (10)

1. The modified waterproof anti-crack cement mortar is characterized by being prepared from the following raw materials in parts by weight:

30-42 parts of cement, 155 parts of sand, 172 parts of water, 15-22 parts of modified organosilicon waterproofing agent, 0.1-1.5 parts of polypropylene fiber, 5-13 parts of rubber powder and 1-3 parts of additive.

2. The modified waterproof anti-crack cement mortar of claim 1, wherein the water cement ratio is 42-58%.

3. The modified waterproof anti-cracking cement mortar of claim 1, wherein the modified silicone waterproofing agent is selected from any one of modified silicone waterproofing agent P750, modified silicone waterproofing agent P730 and modified silicone waterproofing agent WR 2.

4. The modified waterproof anti-crack cement mortar of claim 1, wherein the rubber powder is at least one selected from dispersible latex powder, asphalt modified rubber powder and rubber powder 8031H.

5. The modified waterproof anti-crack cement mortar of any one of claims 1 to 4, wherein the admixture comprises an expanding agent, a water reducing agent and a water retaining agent.

6. The modified waterproof anti-cracking cement mortar of claim 5, wherein the weight ratio of the expanding agent, the water reducing agent and the water retaining agent is (0.1-0.5): 1: (0.1-0.3).

7. The modified waterproof anti-crack cement mortar of claim 1, wherein the sand comprises machine-made sand and natural sand.

8. The modified waterproof anti-cracking cement mortar of claim 7, wherein the weight ratio of the machine-made sand to the natural sand is (0.3-0.7): 1.

9. The modified waterproof anti-crack cement mortar of claim 8, wherein the grain size of the machine-made sand is 0.1-0.5 mm.

10. The method for preparing modified waterproof anti-crack cement mortar according to any one of claims 1 to 9, comprising the following preparation steps:

uniformly mixing cement, sand, polypropylene fiber and rubber powder to obtain a dry mixture;

adding the modified organic silicon waterproof agent and the additive into water, and uniformly mixing to obtain a mixed solution;

and uniformly mixing the dry mixture and the mixed solution to obtain the mortar.