CN109455979B - Waterproof modified cement and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of cement materials, in particular to waterproof modified cement which comprises the following raw materials in parts by weight: 60-100 parts of limestone, 5-15 parts of fly ash, 5-10 parts of montmorillonite, 3-8 parts of diatomite, 20-45 parts of quartz sand, 3-8 parts of a water reducing agent, 3-6 parts of a dispersing agent, 30-50 parts of polyacrylate emulsion, 5-10 parts of hollow glass beads and 60-150 parts of water, wherein the weight part ratio of the polyacrylate emulsion to the hollow glass beads is 5-8; the waterproof and anti-permeability performance of the cement can be improved; the invention also provides a preparation method of the waterproof modified cement, which comprises the steps of adding the hollow glass beads for three times, stirring and mixing at the speed of 50-80r/min, and obtaining the waterproof modified cement, so that the structural integrity of the hollow glass beads can be ensured.

Description

Waterproof modified cement and preparation method thereof

Technical Field

The invention relates to the technical field of cement materials, in particular to waterproof modified cement and a preparation method thereof.

Background

The cement is the most common building material with higher strength in modern buildings, and is applied to the aspects of building construction, ground road construction and the like. In the cement processing process, in order to improve the uniform dispersibility of each raw material component and improve the compactness and comprehensive performance of cement, an emulsifier, a dispersant and other additives and various fillers with different particle sizes are added while stirring and mixing, bubbles are generated in the mixing process of granular solid and liquid, if measures are not taken, more bubbles are left in the cement to influence the dispersion uniformity of the materials, the integral strength of the cement is reduced after hardening, cracking and other conditions are easy to occur at a foaming part, once cracking occurs, external moisture can permeate into a cement layer through the cracks, and the impermeability of a cement product is poor.

In the prior art, in order to overcome the foaming condition in the cement processing process, a method of adding a defoaming agent is mostly adopted to eliminate or weaken the foaming rate, and although the foaming rate has a certain effect, partial bubbles still remain in the solidified cement to influence the impermeability and the waterproofness of the cement.

The invention patent application with application publication number CN 107365139A discloses high-efficiency waterproof modified cement and a preparation method thereof, wherein the high-efficiency waterproof modified cement comprises the following raw materials in parts by weight: 80-100 parts of cement, 30-50 parts of quartz sand, 20-40 parts of fine sand, 20-30 parts of bentonite, 10-35 parts of talcum powder, 40-60 parts of modified butyl acrylate emulsion, 10-20 parts of silicon dioxide, 15-20 parts of calcium hydroxide, 8-10 parts of silicone-acrylate emulsion, 7-13 parts of glyceryl tristearate, 9-18 parts of defoaming agent, 5-15 parts of additive, 4-12 parts of water reducing agent, 8-16 parts of preservative, 5-10 parts of dispersing agent, 6-9 parts of flame retardant and water. The added modified butyl acrylate emulsion can enhance the compactness in the cement, tightly block molecular gaps, improve the waterproofness of the cement and further prevent water from permeating and cracking. However, a large amount of bubbles are generated in the process of stirring and mixing the modified butyl acrylate emulsion and the silicone-acrylate emulsion with solid particles such as quartz sand, so that when the modified butyl acrylate emulsion fills the gaps in the cement, many fine bubbles are generated at the filling position along with the dissolution of the modified butyl acrylate emulsion and the silicone-acrylate emulsion, and the fine bubbles remain in the cement, although the influence on the dispersibility of each aggregate is small, the inside of the cement can meet a certain tightness, once the cement cracks or cracks appear, the fine bubbles are in strip-shaped linkage, and the cracks grow longer and longer, so that the waterproof and anti-permeability performance and strength of the cement are influenced.

Disclosure of Invention

Aiming at the defects in the prior art, the first object of the invention is to provide waterproof modified cement, which can improve the waterproof and anti-permeability performance of the cement.

The first purpose of the invention is realized by the following technical scheme:

the waterproof modified cement comprises the following raw materials in parts by weight: 60-100 parts of limestone, 5-15 parts of fly ash, 5-10 parts of montmorillonite, 3-8 parts of diatomite, 20-45 parts of quartz sand, 3-8 parts of a water reducing agent, 3-6 parts of a dispersing agent, 30-50 parts of polyacrylate emulsion, 5-10 parts of hollow glass beads and 60-150 parts of water, wherein the weight part ratio of the polyacrylate emulsion to the hollow glass beads is 5-8.

By adopting the technical scheme, the hollow glass beads are tiny spheres, have large spherical rate and minimum specific surface area, can have good dispersibility in a cement aggregate mixture, and are easy to compact, so the hollow glass beads have high filling performance; the hollow glass microballoon contains gas with good cold and heat shrinkage resistance, thereby enhancing the temperature change resistance of cement, reducing the cracking of the cement caused by the influence of expansion and contraction of heat, and improving the impermeability of the cement. The polyacrylate emulsion (NBS copolymer) is acrylate copolymer emulsion, is water dispersion of high molecular polymer, and is added into cement mortar to form polymer cement mortar with excellent adhesion, crack resistance, freezing resistance, seepage resistance, corrosion resistance, chlorine ion permeation resistance, aging resistance and corrosion resistance. According to the invention, by adding the polyacrylate emulsion and the hollow glass beads into the aggregate limestone, the fly ash, the montmorillonite, the diatomite and the quartz sand and controlling the adding proportion of the polyacrylate emulsion and the hollow glass beads, bubbles generated in cement are blocked by the hollow glass beads to close the pores, the polyacrylate emulsion can improve the bonding property between the aggregates, so that the structure is more compact and the matrix is interpenetrated with the cement paste, and the polymer is filled in a gap channel formed by the hollow glass beads and the aggregates, so that the internal compactness of the cement is improved. The polyacrylate emulsion is matched with the hollow glass beads to form a closed-cell structure in the cement aggregate, so that bubbles in the cement aggregate can be reduced under the condition of not using a defoaming agent, the internal structure of the cement is more compact, the strength of the cement is enhanced, the cracking rate of the cement is reduced, and the impermeability and the water resistance of the cement are enhanced.

Preferably, the feed comprises the following raw materials in parts by weight: 70-90 parts of limestone, 8-12 parts of fly ash, 5-8 parts of montmorillonite, 3-5 parts of diatomite, 25-40 parts of quartz sand, 3-5 parts of a water reducing agent, 3-5 parts of a dispersing agent, 30-40 parts of polyacrylate emulsion, 5-8 parts of hollow glass beads and 70-100 parts of water, wherein the weight part ratio of the polyacrylate emulsion to the hollow glass beads is 6-8.

By adopting the technical scheme, the content of each component is optimized, so that the cement has better waterproof and anti-permeability performance.

Preferably, the diatomite has the particle size of 900-1000 meshes and is prepared by calcining at 950 ℃.

Preferably, the particle sizes of the limestone and the quartz sand are both 220-250 meshes.

By adopting the technical scheme, the particle size of the aggregate is reduced, and the dispersion uniformity of the aggregate in the cement is further improved on the basis of ensuring that the aggregate can meet the cement strength, so that the compactness of the interior of the cement is further improved.

Preferably, the water reducing agent is a polycarboxylic acid high-performance water reducing agent.

By adopting the technical scheme, the polycarboxylic acid high-performance water reducing agent really designs an effective molecular structure according to the action mechanism of the dispersed cement, has a super-dispersion type, can prevent the slump loss of concrete without causing obvious slow setting, exerts a higher plasticizing effect under a low doping amount, has the technical performance characteristics of good fluidity retentivity, large freedom degree on molecular structure, obvious concrete reinforcing effect, capability of reducing concrete shrinkage, extremely low content of harmful substances and the like, and endows the concrete with excellent durability. The polycarboxylic acid high-performance water reducing agent has good comprehensive technical performance advantages and environmental protection characteristics, and meets the requirements of modern concrete engineering.

Preferably, the dispersant is vinyl bis stearamide.

By adopting the technical scheme, the vinyl bis stearamide is also called Ethylene Bis Stearamide (EBS), the compound is hard and brittle white high-melting-point wax, the industrial product is slightly yellowish fine particles, the wax is non-toxic and has no side effect on human bodies, the cold-temperature plastic flow can be reduced by adding the compound into cement, and the water resistance, acid resistance, salt water spray resistance and other properties of the cement are improved on the premise of not becoming brittle.

The second purpose of the invention is to provide a preparation method of the waterproof modified cement, and the modified cement with anti-permeability and waterproof properties is prepared.

The second purpose of the invention is realized by the following technical scheme:

a preparation method of waterproof modified cement comprises the following operation steps:

adding limestone, fly ash and montmorillonite into 1/3 water, mixing and stirring to obtain a mixture A;

adding water in the total amount of 1/3 water into the diatomite, the quartz sand and the water reducing agent, and mixing and stirring to obtain a mixture B;

uniformly mixing the polyacrylate emulsion and the balance of water, adding the hollow glass beads in three times, adding 1/2 total amount of the hollow glass beads for the first time, 1/4 total amount of the hollow glass beads for the second time, 1/4 total amount of the hollow glass beads for the third time, and stirring at the speed of 50-80r/min for 3-5min after adding the hollow glass beads each time to obtain a mixture C;

and adding the dispersing agent, the mixture A and the mixture B into the mixture C, and stirring at the speed of 50-80r/min for 5-10min to obtain the waterproof modified cement.

By adopting the technical scheme, limestone, fly ash and montmorillonite are mixed with water and stirred to obtain an aggregate I, namely a mixture A; mixing diatomite and quartz sand with a water reducing agent, and uniformly stirring and mixing to obtain aggregate II, namely a mixture B; the hollow glass beads are added into the polyacrylate emulsion for three times and are gradually added, so that the hollow glass beads can be well prevented from floating and gathering to a certain part in the cement, the dispersion is more complete, and the hollow glass beads seal the holes of the bubbles of the polyacrylate emulsion; when the hollow glass beads are added, the structural integrity of the hollow glass beads is ensured under the condition of mild stirring speed, so that the hollow glass beads can play a role in supporting strength and sealing holes. And adding the dispersing agent, the mixture A and the mixture B into the mixture C, uniformly dispersing the aggregate at a mild stirring speed, filling the polyacrylate emulsion into a gap pore channel formed by the hollow glass beads and the aggregate, and finally preparing the waterproof modified cement with compact interior and impermeability.

Preferably, in the preparation process of the mixture A, the mixture A is stirred and mixed at the speed of 300-500r/min for 15-25min and then is subjected to ball milling, and the mixture A is obtained after the ball milling is carried out for 10-20 min.

Preferably, in the preparation process of the mixture B, the mixture B is stirred and mixed at the speed of 300-500r/min for 10-20min, and then ball milling is carried out for 10-15min to obtain the mixture B.

By adopting the technical scheme, the particle sizes of the mixture A and the mixture B obtained by stirring and mixing are more uniform, and the uniform dispersion is facilitated.

In conclusion, the invention has the following beneficial effects:

(1) by adding the hollow glass beads and the polyacrylate emulsion into the raw materials and performing synergistic cooperation of the hollow glass beads and the polyacrylate emulsion, the impermeability and the compressive strength of the waterproof modified cement reach II type, the 28d impervious pressure reaches 2.2MPa at most, the compressive strength reaches 54.0MPa at most, and the water absorption rate is reduced to 2.8% at least;

(2) by controlling the proportion of the hollow glass beads and the polyacrylate emulsion, all detection results of the modified cement reach the excellent performance of type II;

(3) the hollow glass beads are added in batches by controlling the stirring speed, so that the hollow glass beads can keep an integral structure, and the hollow glass beads can play a role.

Detailed Description

The present invention will be further described with reference to the following specific examples.

The water reducing agent is a polycarboxylic acid high-performance water reducing agent selected from Nantong Runfeng petrochemical company Limited, the solid content is 20 +/-2%, the density is 1.08 +/-0.02 g/ml, the pH value is 6-7, the chloride ion is less than 0.05, the fluidity of cement paste is 0.29-250 mm. The dispersant is vinyl bis stearamide, the content of molybdenum is more than or equal to 99 percent, the granularity is 5000 meshes, and the grade is MP-1. The polyacrylate emulsion is selected from Beijing Jiahe synthetic New technology, Inc., TH model.

Example 1

The waterproof modified cement is prepared by the following operation steps:

pretreatment of raw materials: passing the diatomite calcined at 950 deg.C (the calcining method is mature prior art and is not described herein) through a 900 mesh screen, and screening to obtain 900 mesh diatomite; and screening the limestone and the quartz sand by a 220-mesh screen to obtain the limestone and the quartz sand with the particle size of 220 meshes for later use.

Mixing the aggregate: limestone, fly ash and montmorillonite are added into water of 1/3 water according to the addition amount in the table 1, stirred and mixed for 25min at the speed of 300r/min, and then sent into a ball mill for ball milling for 20min to obtain a mixture A.

Mixing the aggregate: according to the addition amounts in the table 1, the diatomite, the quartz sand and the water reducing agent are added into water with the total amount of 1/3 water, stirred and mixed for 20min at the speed of 300r/min, and then sent into a ball mill for ball milling, and the mixture B is obtained after ball milling for 15 min.

According to the addition amount in the table 1, uniformly mixing the polyacrylate emulsion and the balance of water (namely 1/3 total water), adding the hollow glass beads in three times, adding 1/2 total amount of the hollow glass beads in the first time, 1/4 total amount of the hollow glass beads in the second time, adding 1/4 total amount of the hollow glass beads in the third time, and stirring at the speed of 50r/min for 5min after adding the hollow glass beads each time to obtain a mixture C.

And (3) adding the dispersing agent, the mixture A and the mixture B into the mixture C according to the addition amount in the table 1, and stirring at the speed of 50r/min for 10min to obtain the waterproof modified cement.

Example 2

The waterproof modified cement is prepared by the following operation steps:

pretreatment of raw materials: the diatomite which is calcined at 950 ℃ (the calcining method is mature prior art and is not described herein) is screened by a 1000-mesh screen to obtain the diatomite with the particle size of 1000 meshes for later use; and screening the limestone and the quartz sand by a 250-mesh screen to obtain the limestone and the quartz sand with the particle size of 250 meshes for later use.

Mixing the aggregate: according to the addition amount in the embodiment 1, limestone, fly ash and montmorillonite are added into water of 1/3 water total amount, stirred and mixed for 20min at the speed of 500r/min, and then sent into a ball mill for ball milling, and the mixture A is obtained after ball milling for 10 min.

Mixing the aggregate: according to the addition amount in the example 1, the diatomite, the quartz sand and the water reducing agent are added into water of 1/3 water total amount, the mixture is stirred and mixed for 10min at the speed of 500r/min, then the mixture is sent into a ball mill for ball milling, and the mixture B is obtained after the ball milling is carried out for 10 min.

According to the addition amount in example 1, uniformly mixing the polyacrylate emulsion and the balance of water (namely 1/3 total water), adding hollow glass beads in three times, adding 1/2 total amount of hollow glass beads for the first time, 1/4 total amount of hollow glass beads for the second time and 1/4 total amount of hollow glass beads for the third time, and stirring at the speed of 80r/min for 3min after adding the hollow glass beads each time to obtain a mixture C.

And (3) adding the dispersing agent, the mixture A and the mixture B into the mixture C according to the addition amount in the example 1, and stirring at the speed of 80r/min for 5min to obtain the waterproof modified cement.

Example 3

The waterproof modified cement is prepared by the following operation steps:

pretreatment of raw materials: the diatomite which is calcined at 950 ℃ and prepared (the calcining method is mature prior art and is not described herein) is screened by a 960-mesh screen to obtain the diatomite with the particle size of 960 meshes for later use; and screening the limestone and the quartz sand by a 240-mesh screen to obtain the limestone and the quartz sand with the particle size of 240 meshes for later use.

Mixing the aggregate: according to the addition amount in the embodiment 1, limestone, fly ash and montmorillonite are added into water of 1/3 water total amount, stirred and mixed for 15min at the speed of 400r/min, and then sent into a ball mill for ball milling, and the mixture A is obtained after ball milling for 10 min.

Mixing the aggregate: according to the addition amount in the example 1, the diatomite, the quartz sand and the water reducing agent are added into 1/3 water, the total amount of water is stirred and mixed for 15min at the speed of 400r/min, then the mixture is sent into a ball mill for ball milling, and the mixture B is obtained after ball milling for 12 min.

According to the addition amount in example 1, uniformly mixing the polyacrylate emulsion and the balance of water (namely 1/3 total water), adding hollow glass beads in three times, adding 1/2 total amount of hollow glass beads for the first time, 1/4 total amount of hollow glass beads for the second time and 1/4 total amount of hollow glass beads for the third time, and stirring at the speed of 66r/min for 3min after adding the hollow glass beads each time to obtain a mixture C.

And adding the dispersing agent, the mixture A and the mixture B into the mixture C according to the addition amount in the example 1, and stirring at the speed of 70r/min for 5min to obtain the waterproof modified cement.

Examples 4 to 9

The waterproof modified cements of examples 4 to 9 were prepared in the same manner as in example 3, except that the addition amounts of the respective raw material components were different, and the specific addition amounts are shown in Table 1.

TABLE 1 addition amounts of respective raw material components for preparing water-proof modified cements in examples 1 to 9

Comparative example 1

Comparative example 1 differs from example 3 in that: the raw material of comparative example 1 was free of hollow glass beads, and the rest was identical to that of example 3.

Comparative example 2

Comparative example 2 differs from example 3 in that: the starting material in comparative example 2 was free of polyacrylate emulsion, the remainder being identical to example 3.

Comparative example 3

Comparative example 3 differs from example 3 in that: the raw materials in comparative example 3 were free of polyacrylate emulsion and hollow glass microspheres, and the rest was identical to example 3.

Comparative example 4

Comparative example 4 differs from example 3 in that: the weight part ratio of the polyacrylate emulsion to the hollow glass beads in the raw materials of the comparative example 4 was 4, and the rest was the same as that of the example 3.

Comparative example 5

Comparative example 5 differs from example 3 in that: the weight part ratio of the polyacrylate emulsion to the hollow glass beads in the raw materials of the comparative example 5 was 9, and the rest was the same as that of the example 3.

Comparative example 6

Comparative example 6 differs from example 3 in that: in the preparation process of the mixture C in the comparative example 6, the hollow glass beads were added all at once and stirred at a speed of 66r/min for 3min to obtain a mixture C, and the rest was the same as in example 3.

Comparative example 7

Comparative example 7 differs from comparative example 6 in that: in the preparation process of the mixture C in the comparative example 7, after all the hollow glass beads are added at one time, the mixture C is obtained by stirring at the speed of 100r/min for 3min, and the rest is the same as that in the example 3.

The high-efficiency waterproof modified cement prepared in example 2 in the invention patent application with the publication number of CN 107365139A in the comparison group.

The amounts of the respective raw material components added in the waterproof modified cements of comparative examples 1 to 7 are specifically shown in the following table 2.

TABLE 2 addition amounts of respective raw material components for producing waterproof modified cements in comparative examples 1 to 7

Performance detection

The modified cements of examples 1-9, comparative examples 1-7 and control were subjected to performance measurement according to the detection standard and detection method of JC/T984-2011, and the specific detection results are shown in tables 3 and 4, respectively.

TABLE 3 Performance test results for waterproof modified cements prepared in examples 1-9

The detection results in the table 3 show that 28d of the waterproof modified cement prepared by the formula and the preparation method of the invention has the highest seepage pressure of 2.2MPa, the highest compressive strength of 54.0MPa and the lowest water absorption rate of 2.8 percent, and in addition, the setting time, the bonding strength, the frost resistance and the shrinkage rate all reach the II-type index in the detection standard, thereby achieving excellent performance.

TABLE 4 Performance test results for waterproof modified cements of comparative examples 1-7 and control

The detection results in table 4 show that the performances of the waterproof modified cement prepared by the invention are superior to those of the high-efficiency waterproof modified cement in the patent of the control group. The formula and the preparation method of the invention have great influence on the impermeability of the waterproof modified cement. As can be seen from comparative examples 1 to 5, the polyacrylate emulsion and the hollow glass beads in the invention have great influence on the impermeability and compressive strength of the waterproof modified cement of the invention, if the hollow glass beads are removed (comparative example 1), the 28d impermeability pressure of the modified cement is reduced to 1.4MPa, the compressive strength is reduced from type II to type I, 21MPa, the water absorption rate is increased to 4.9%, the impermeability and waterproof performance is greatly reduced, and the strength is also reduced; if the effects of compressive strength, permeation resistance pressure, setting time, bonding strength, frost resistance, water absorption and shrinkage rate of the polyacrylate emulsion (comparative example 2) are removed, the effects are reduced; if the polyacrylate emulsion and the hollow glass beads are removed (comparative example 3), the 28d impervious pressure of the modified cement is reduced to 1.0Mpa, the compressive strength is reduced from type II to type I, 15Mpa, the water absorption rate is increased to 5.3 percent, the impervious and waterproof properties are seriously reduced, and other properties are obviously reduced; it can be seen from comparative examples 4 and 5 that the proportion of the polyacrylate emulsion and the hollow glass beads in the invention has a certain influence on the waterproof and anti-permeability performance of the finally obtained modified cement, and if the proportion is not within the scope of the invention, the permeation resistance pressure, the compressive strength, the water absorption rate and the shrinkage rate are all reduced from type II to type I. The results of comparative example 6 and comparative example 7 show that in the preparation method of the invention, the adding time and the stirring speed of the hollow glass beads play a key role in the action of the hollow glass beads, and if the hollow glass beads are added all at one time, the dispersion of the hollow glass beads is not uniform, which affects the performance of the final modified cement; if the stirring speed is too high after the addition, the structural integrity of the hollow glass beads can be damaged, the supporting strength of the hollow glass beads to the modified cement is reduced, and the performances of the modified cement such as the compressive strength are reduced.

The above-mentioned embodiments are merely illustrative and not restrictive, and those skilled in the art can modify the embodiments without inventive contribution as required after reading this specification, but only fall within the scope of the claims of the present invention.

Claims (6)

1. The waterproof modified cement is characterized by comprising the following raw materials in parts by weight: 60-100 parts of limestone, 5-15 parts of fly ash, 5-10 parts of montmorillonite, 3-8 parts of diatomite, 20-45 parts of quartz sand, 3-8 parts of a water reducing agent, 3-6 parts of a dispersing agent, 30-50 parts of polyacrylate emulsion, 5-10 parts of hollow glass beads and 60-150 parts of water, wherein the weight part ratio of the polyacrylate emulsion to the hollow glass beads is 5-8.

2. The waterproof modified cement of claim 1, which is characterized by comprising the following raw materials in parts by weight: 70-90 parts of limestone, 8-12 parts of fly ash, 5-8 parts of montmorillonite, 3-5 parts of diatomite, 25-40 parts of quartz sand, 3-5 parts of a water reducing agent, 3-5 parts of a dispersing agent, 30-40 parts of polyacrylate emulsion, 5-8 parts of hollow glass beads and 70-100 parts of water, wherein the weight part ratio of the polyacrylate emulsion to the hollow glass beads is 6-8.

3. The waterproof modified cement of claim 1, wherein: the particle size of the diatomite is 900-1000 meshes, and the diatomite is prepared by calcining at 950 ℃.

4. The waterproof modified cement of claim 1, wherein: the particle sizes of the limestone and the quartz sand are both 220-250 meshes.

5. The waterproof modified cement of claim 1, wherein: the water reducing agent is a polycarboxylic acid high-performance water reducing agent.

6. The waterproof modified cement of claim 1, wherein: the dispersing agent is vinyl bis stearamide.