CN110642563A

CN110642563A - Dry powder mortar for pavement and preparation process thereof

Info

Publication number: CN110642563A
Application number: CN201911031979.8A
Authority: CN
Inventors: 张立; 周宇武; 王彬彬; 唐圳
Original assignee: Ningbo New Guangyi Building Materials Co Ltd
Current assignee: Ningbo New Guangyi Building Materials Co Ltd
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2020-01-03

Abstract

The invention relates to dry powder mortar for a pavement and a preparation process thereof, relating to the technical field of building materials, and specifically comprising the following components in percentage by weight: 11-13% of cement, 6-8% of mineral powder, 17-20.5% of fly ash, 26-33% of yellow sand, 9-11% of modified bentonite, 10-13% of stone powder, 2.5-4% of thickening powder, 1-2% of a waterproof agent, 1-2.5% of redispersible latex powder, 1-2% of expanded perlite and 1.5-3% of an additive, wherein the preparation method of the modified bentonite comprises the following steps: 1) adding 20-30 kg of glucose into 300-400L of water, and stirring until the glucose is completely dissolved; 2) then continuously adding 100-120 kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, then raising the temperature to 80-120 ℃, stirring for 4-6 h, centrifuging after stirring is finished, washing the precipitate for 3-5 times by using water, and drying. The mortar prepared by the invention has the effects of good wear resistance, long service life of the pavement and reduction of the maintenance cost of the pavement when being paved on the pavement.

Description

Dry powder mortar for pavement and preparation process thereof

Technical Field

The invention relates to the technical field of building materials, in particular to dry powder mortar for a pavement and a preparation process thereof.

Background

The dry powder mortar is a granular or powder mixture prepared by uniformly mixing cement, sand, mineral admixture and functional additive in a certain proportion in a dry state in a professional production plant, then transporting the mixture to a construction site in a dry powder package or bulk form, and adding water according to the specification to mix the mixture to obtain the dry powder mortar material which can be directly used. After premixing and prepackaging dry powder mortar to replace the field mortar mixing, more and more mechanized construction is used, and the modern construction system can greatly improve the production efficiency and the engineering quality.

The Chinese patent with the publication number of CN10183838129B discloses dry powder mortar, which comprises the following components: 12-25% of cement, 3-4% of fly ash, 32-50% of yellow sand, 32-50% of sodium silicate casting used sand, 2.7-3.4% of mortar thickening powder and 0-0.05% of an additive.

The above prior art solutions have the following drawbacks: the sodium silicate casting used sand contains dehydrated high-modulus sodium silicate water glass, sodium carbonate and sodium bicarbonate, which can cause adverse effects on the construction performance and mechanical properties of the dry powder mortar, and the dry powder mortar is coated on the pavement after being uniformly stirred by adding water, so that the wear resistance of the pavement can be affected, the service life of the pavement is shortened, and the maintenance cost of the pavement is increased.

Disclosure of Invention

The invention aims to provide the dry powder mortar for the road surface, and the mortar has the effects of good wear resistance, long service life of the road surface and reduction of the maintenance cost of the road surface when being paved on the road surface; the invention also aims to provide a preparation process of the dry-mixed mortar for the pavement.

The technical purpose of the invention is realized by the following technical scheme: the dry powder mortar for the pavement specifically comprises the following components in percentage by weight: 11-13% of cement, 6-8% of mineral powder, 17-20.5% of fly ash, 26-33% of yellow sand, 9-11% of modified bentonite, 10-13% of stone powder, 2.5-4% of thickening powder, 1-2% of a waterproof agent, 1-2.5% of redispersible latex powder, 1-2% of expanded perlite and 1.5-3% of an additive, wherein the preparation method of the modified bentonite comprises the following steps: 1) adding 20-30 kg of glucose into 300-400L of water, and stirring until the glucose is completely dissolved; 2) then continuously adding 100-120 kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, raising the temperature to 80-120 ℃, stirring for 4-6 h, centrifuging after stirring, washing the precipitate for 3-5 times by using water, drying at the drying temperature lower than 140 ℃, and grinding into powder to obtain the modified bentonite.

By adopting the technical scheme, cement and water form cement slurry, the cement slurry wraps the surfaces of the yellow sands and fills gaps between the yellow sands, the cement slurry plays a role in lubricating before the mortar is coagulated and hardened, so that the newly mixed mortar has workability suitable for construction, the hardened cement enables the mortar to have the cost of the mortar, in addition, the addition of the yellow sands can improve the durability of the mortar, and the adverse phenomena of heating, drying shrinkage and the like of the cement slurry are reduced. The addition of the fly ash and the stone powder can improve the workability of the freshly mixed mortar and improve the compactness, impermeability, chemical corrosion resistance and the like of the freshly mixed mortar. Mineral powder is used as industrial waste and added into mortar to replace partial cement in equal amount, so that the addition of cement is reduced, and the production cost of mortar is reduced on the premise of not affecting the strength of mortar.

The bentonite is a layered inorganic silicate, swells to form flocculent substances after absorbing water, has good suspension property and dispersibility, is combined with a proper amount of water to form colloid, can release charged particles in the water, increases the viscosity of a system, and improves the bonding effect between mortar and pavement concrete. The modified bentonite is prepared by adsorbing glucose between bentonite layers, a large amount of glucose adsorbed by the bentonite is stabilized between the bentonite layers, a plurality of hydroxyl groups of the glucose and free water molecules form hydrogen bonds to bind the free water in a large amount of mortar, so that the water retention performance of the fresh mortar is greatly improved, and the fresh mortar with the water retention performance has excellent mechanical properties, compressive strength, flexural strength, bonding tensile strength and other properties. In addition, because the glucose molecules and the bentonite both contain hydroxyl groups, the hydroxyl groups can form hydrogen bonds with a large number of hydroxyl groups in a cement hydration product, so that the compactness of an interface is improved, the adhesion strength of the interface is enhanced, the interface effect of fiber blocking and enhancing is enlarged, the expansion of micro cracks in a cement matrix is prevented, and the tension, the breaking strength and the breaking performance of the mortar are improved.

Cement is in the solidification process that congeals, inside can produce many cavitys and become the weak position of cement base member, but add redispersable emulsion powder, when cement congeals the solidification, emulsion powder meets the water and immediately disperses into the emulsion to gather in rich water area, along with going on of drying process, the emulsion dewaters once more, the polymer has formed the continuous film of one deck all around the cavity, these weak positions have been strengthened, because continuous organic matter film can disperse stress again, so can play the effect of toughening to the mortar, strengthen the rupture strength of mortar, reduce the ratio of buckling of mortar. The expanded perlite and the redispersible latex powder are used in a composite way, so that the defects of the redispersible latex powder are overcome by the advantages of the fine powder of the expanded perlite, the two components are combined to exert better effect than the respective single use, on one hand, the use amount of the redispersible latex powder can be reduced, and on the other hand, the industrial waste of the fine powder of the expanded perlite can be recycled.

The invention is further provided with: the waterproof agent is calcium stearate.

By adopting the technical scheme, the calcium stearate has low cost and good surface hydrophobic effect.

The invention is further provided with: the additive comprises a water reducing agent, a water retaining agent, a defoaming agent and an air entraining agent.

By adopting the technical scheme, the water reducing agent can obviously reduce the water-cement ratio of the mortar under the condition of keeping the workability of the mortar unchanged, so that the strength, the impermeability and the durability of a hardened body are improved. The water-retaining agent can avoid mortar segregation and premature loss of water, improve the workability of mortar and facilitate mortar construction. In the process of adding water into mortar and stirring, the mortar is stirred, air is brought into newly-mixed mortar, the air is wrapped by wet mortar to form bubbles, and some components containing hydrophilic groups in the mortar can reduce the surface tension of liquid and also cause foam aggregation, so that a large amount of bubbles introduced into the mortar stay in the mortar, the bubbles are increased, the porosity of the mortar is increased, and the self strength of the mortar is reduced. And adding the defoaming agent, wherein the defoaming agent slowly enters the liquid film, so that the viscosity of the liquid is reduced, a new low-surface-viscosity interface is formed, the liquid film loses elasticity, the liquid seepage process is accelerated, and finally the liquid film is thinned and broken. The air entraining agent can introduce quantitative micro bubbles into the mortar, has the main functions of reducing bleeding and segregation phenomena of the mortar, improving the workability, having a certain function of improving the durability of the mortar and having no obvious influence on the setting and hardening speed of the cement.

The invention is further provided with: the mass ratio of the water reducing agent, the water-retaining agent, the defoaming agent and the air entraining agent in the additive is 6: 5: 4: 5.

by adopting the technical scheme, under the condition of the proportion, the effect of various additives is the best.

The invention is further provided with: the water reducing agent is lignosulphonate.

By adopting the technical scheme, the lignosulfonate is an anionic surfactant, has strong dispersing capacity, can uniformly disperse solids in an aqueous medium, contains various active groups, and can generate condensation or generate hydrogen bond with other compounds. The lignosulfonate is added into the mortar, so that the surface tension and the interfacial tension of water can be reduced, and the water reducing effect is achieved.

The invention is further provided with: the defoaming agent is a dry powder defoaming agent.

By adopting the technical scheme, the dry powder defoaming agent belongs to an organosilane defoaming agent and has the characteristics of acid resistance, alkali resistance and high temperature resistance.

The invention is further provided with: the paint specifically comprises the following components in percentage by weight: 11.8% of cement, 6.5% of mineral powder, 19.3% of fly ash, 29.2% of yellow sand, 10.4% of modified bentonite, 12.5% of stone powder, 3.1% of thickening powder, 1.5% of a waterproof agent, 2% of redispersible latex powder, 1.7% of expanded perlite and 2% of an additive.

The invention is further provided with: the fineness modulus of the yellow sand is more than 3.0.

By adopting the technical scheme, the yellow sand with the fineness modulus of more than 3.0 is coarse sand, and the abrasion resistance coefficient of the coarse sand is large, so that the abrasion resistance of the mortar can be improved.

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

The preparation process of the dry powder mortar for the noodles specifically comprises the following steps:

step 1, drying yellow sand by a dryer, wherein the moisture content of the dried yellow sand is less than 0.5%, screening the dried yellow sand, and then placing the screened yellow sand in a storage tank for later use;

step 2, weighing the components according to the formula, mixing and stirring uniformly to obtain dry-mixed mortar, and then packaging the dry-mixed mortar for later use.

By adopting the technical scheme, the preparation process is simple, convenient to operate and suitable for mass production of the dry-mixed mortar.

In conclusion, the beneficial technical effects of the invention are as follows:

1. the bentonite is a layered inorganic silicate, swells to form flocculent substances after absorbing water, has good suspension property and dispersibility, is combined with a proper amount of water to form colloid, can release charged particles in the water, increases the viscosity of a system, and improves the bonding effect between mortar and pavement concrete. The modified bentonite is prepared by adsorbing glucose between bentonite layers, a large amount of glucose adsorbed by the bentonite is stabilized between the bentonite layers, a plurality of hydroxyl groups of the glucose and free water molecules form hydrogen bonds to bind the free water in a large amount of mortar, so that the water retention performance of the fresh mortar is greatly improved, and the fresh mortar with the water retention performance has excellent mechanical properties, compressive strength, flexural strength, bonding tensile strength and other properties. In addition, because the glucose molecules and the bentonite both contain hydroxyl groups, the hydroxyl groups can form hydrogen bonds with a large number of hydroxyl groups in a cement hydration product, so that the compactness of an interface is improved, the adhesion strength of the interface is enhanced, the interface effect of fiber blocking and enhancing is enlarged, the expansion of micro cracks in a cement matrix is prevented, and the tension stress effect borne by the micro cracks is prevented, so that the tensile strength, the breaking strength and the breaking performance of the mortar are improved;

2. cement is in the solidification process that congeals, inside can produce many cavitys and become the weak position of cement base member, but add redispersable emulsion powder, when cement congeals the solidification, emulsion powder meets the water and immediately disperses into the emulsion to gather in rich water area, along with going on of drying process, the emulsion dewaters once more, the polymer has formed the continuous film of one deck all around the cavity, these weak positions have been strengthened, because continuous organic matter film can disperse stress again, so can play the effect of toughening to the mortar, strengthen the rupture strength of mortar, reduce the ratio of buckling of mortar. The expanded perlite and the redispersible latex powder are used in a composite way, so that the defects of the redispersible latex powder are overcome by the advantages of the fine powder of the expanded perlite, the two are combined to exert a better effect than that of the two used independently, on one hand, the use amount of the redispersible latex powder can be reduced, and on the other hand, the fine powder of the expanded perlite, which is an industrial waste, can be recycled;

3. the lignosulfonate is an anionic surfactant, has strong dispersing capacity, can uniformly disperse solids in an aqueous medium, contains various active groups, and can generate condensation or generate hydrogen bond with other compounds. The lignosulfonate is added into the mortar, so that the surface tension and the interfacial tension of water can be reduced, and the water reducing effect is achieved.

Detailed Description

The present invention will be described in further detail with reference to examples.

The cement used in the embodiment and the comparative example of the invention is 425 ordinary portland cement, the mineral powder is mineral powder S95, and the fineness modulus of the yellow sand is more than 3.0.

Example 1

TABLE 1 Dry powder mortar for road surface and its components in weight percent

The preparation method of the modified bentonite comprises the following steps: 1) adding 20kg of glucose into 300L of water, and stirring until the glucose is completely dissolved; 2) then continuously adding 100kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, raising the temperature to 80 ℃, stirring for 6h, centrifuging after stirring, washing the precipitate for 5 times by using water, drying at the drying temperature lower than 140 ℃, and grinding into powder to obtain the modified bentonite.

The preparation process of the dry powder mortar specifically comprises the following steps:

Example 2

TABLE 2 Dry powder mortar for road surface and its components and weight percentages

Components	Weight percent (%)	Components	Weight percent (%)
				Cement	12	Calcium stearate	1
Mineral powder	6	Redispersible latex powder	2
				Fly ash	17	Expanded perlite	2
Yellow sand	33	Lignosulfonic acid calcium salt	0.6
				Modified bentonite	11	Water-retaining agent	0.8
Stone powder	10	Dry powder defoaming agent	0.9
				Thickening powder	3	Air entraining agent	0.7

The preparation method of the modified bentonite comprises the following steps: 1) adding 25kg of glucose into 400L of water, and stirring until the glucose is completely dissolved; 2) then, continuously adding 110kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, raising the temperature to 100 ℃, stirring for 5h, centrifuging after stirring, washing the precipitate for 4 times by using water, drying at the drying temperature lower than 140 ℃, and grinding into powder to obtain the modified bentonite.

The preparation process of the dry powder mortar is the same as that of example 1.

Example 3

TABLE 3 Dry powder mortar for road surface and its components in weight percent

The preparation method of the modified bentonite comprises the following steps: 1) adding 30kg of glucose into 350L of water, and stirring until the glucose is completely dissolved; 2) then, continuously adding 120kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, raising the temperature to 120 ℃, stirring for 4h, centrifuging after stirring, washing the precipitate for 3 times by using water, drying at the drying temperature lower than 140 ℃, and grinding into powder to obtain the modified bentonite.

Example 4

TABLE 4 Dry powder mortar for road surface and its components in weight percent

Components	Weight percent (%)	Components	Weight percent (%)
				Cement	12	Calcium stearate	1.5
Mineral powder	7.2	Redispersible latex powder	1.9
				Fly ash	18	Expanded perlite	1.9
Yellow sand	30	Lignosulfonic acid sodium salt	0.7
				Modified bentonite	10	Water-retaining agent	0.4
Stone powder	12.4	Dry powder defoaming agent	0.3
				Thickening powder	3.2	Air entraining agent	0.5

The preparation method of the modified bentonite is the same as that of the example 2.

Example 5

TABLE 5 Dry powder mortar for road surface and its components in weight percent

Components	Weight percent (%)	Components	Weight percent (%)
				Cement	12.2	Calcium stearate	1.1
Mineral powder	6.1	Redispersible latex powder	2.1
				Fly ash	20.2	Expanded perlite	1.7
Yellow sand	30.3	Lignosulfonic acid sodium salt	0.9
				Modified bentonite	11	Water-retaining agent	0.7
Stone powder	10	Dry powder defoaming agent	0.8
				Thickening powder	2.5	Air entraining agent	0.4

Example 6

TABLE 6 Dry powder mortar for road surface and its components in weight percent

Example 7

TABLE 7 Dry powder mortar for road surface and its components in weight percent

Components	Weight percent (%)	Components	Weight percent (%)
				Cement	11.8	Calcium stearate	1.5
Mineral powder	6.5	Redispersible latex powder	2
				Fly ash	19.3	Expanded perlite	1.7
Yellow sand	29.2	Lignosulfonic acid sodium salt	0.6
				Modified bentonite	10.4	Water-retaining agent	0.5
Stone powder	12.5	Dry powder defoaming agent	0.4
				Thickening powder	3.1	Air entraining agent	0.5

Comparative example 1

A dry mortar for road surfaces is different from that of example 7 in that modified bentonite is not included in the dry mortar component, and the other example is the same as example 7.

Comparative example 2

A dry mortar for road surfaces is different from that of example 7 in that modified bentonite is replaced by bentonite, and the other steps are the same as those of example 7.

Comparative example 3

A dry mortar for road surfaces differs from example 7 in that the components of the dry mortar do not include expanded perlite and redispersible latex powder, and the other components are the same as in example 7.

Comparative example 4

A dry mortar for road surfaces, which is different from example 7 in that the components of the dry mortar do not include expanded perlite, and which is otherwise the same as example 7.

Comparative example 5

A dry mortar for road surfaces differs from example 7 in that the redispersible latex powder is not included in the dry mortar components, and otherwise the same as in example 7.

Preparing cement mortar: adding the prepared dry powder mortar and water into a stirrer according to the ratio of 7:1, uniformly stirring to prepare cement mortar, and then performing the following performance tests:

testing the water retention property of the mortar: the test is operated according to JKGJ/T70-2009 Standard test method for basic performance of building mortar;

testing the compressive strength of the mortar: the test is operated according to JKGJ/T70-2009 Standard test method for basic performance of building mortar;

testing the breaking strength of the mortar: the test is operated according to JKGJ/T70-2009 Standard test method for basic performance of building mortar;

and (3) wear resistance test: the test was carried out according to JTJ053-94 "test for abrasion resistance of concrete".

TABLE 8 results of Performance testing

The dry powder mortar prepared in the embodiment has better performances than the comparative examples, and the comparison between the embodiment 7 and the comparative examples 1 and 1 shows that the modified bentonite can improve the performances of the dry powder mortar; compared with the comparative examples 3-5, the embodiment 7 shows that the addition of the redispersible latex powder and the expanded perlite can improve the mechanical property of the dry powder mortar, and particularly, the re-dispersible latex powder and the expanded perlite are better in performance when being used in combination than when being used alone.

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

Claims

1. A dry powder mortar for road surfaces is characterized in that: the paint specifically comprises the following components in percentage by weight: 11-13% of cement, 6-8% of mineral powder, 17-20.5% of fly ash, 26-33% of yellow sand, 9-11% of modified bentonite, 10-13% of stone powder, 2.5-4% of thickening powder, 1-2% of a waterproof agent, 1-2.5% of redispersible latex powder, 1-2% of expanded perlite and 1.5-3% of an additive, wherein the preparation method of the modified bentonite comprises the following steps: 1) adding 20-30 kg of glucose into 300-400L of water, and stirring until the glucose is completely dissolved; 2) then continuously adding 100-120 kg of bentonite, and continuously stirring to uniformly disperse the bentonite; 3) and adjusting the pH value to 12-13, raising the temperature to 80-120 ℃, stirring for 4-6 h, centrifuging after stirring, washing the precipitate for 3-5 times by using water, drying at the drying temperature lower than 140 ℃, and grinding into powder to obtain the modified bentonite.

2. The dry mortar for road surfaces according to claim 1, characterized in that: the waterproof agent is calcium stearate.

3. The dry mortar for road surfaces according to claim 1, characterized in that: the additive comprises a water reducing agent, a water retaining agent, a defoaming agent and an air entraining agent.

4. The dry mortar for road surfaces according to claim 3, characterized in that: the mass ratio of the water reducing agent, the water-retaining agent, the defoaming agent and the air entraining agent in the additive is 6: 5: 4: 5.

5. the dry mortar for road surfaces according to claim 3, characterized in that: the water reducing agent is lignosulphonate.

6. The dry mortar for road surfaces according to claim 3, characterized in that: the defoaming agent is a dry powder defoaming agent.

7. The dry mortar for road surfaces according to claim 1, characterized in that: the paint specifically comprises the following components in percentage by weight: 11.8% of cement, 6.5% of mineral powder, 19.3% of fly ash, 29.2% of yellow sand, 10.4% of modified bentonite, 12.5% of stone powder, 3.1% of thickening powder, 1.5% of a waterproof agent, 2% of redispersible latex powder, 1.7% of expanded perlite and 2% of an additive.

8. The dry mortar for road surfaces according to claim 1, characterized in that: the fineness modulus of the yellow sand is more than 3.0.

9. A process for preparing a dry mortar for road surfaces according to any one of claims 1 to 8, characterized in that: the method specifically comprises the following steps: