KR102568500B1 - Plastering omitable wet self-filling mortar composition for flooring - Google Patents

Abstract

The present invention relates to a wet self-filling mortar composition for spraying, which can improve performance such as fluidity and shrinkage reduction effect, thereby omitting a plastering process and finishing the surface only with a paste.
The present invention is a mortar composition having a design standard strength of 21 MPa or more, including binder, fine aggregate, mixing water, water reducing agent and shrinkage reducing agent, binder amount 500 ~ 600 kg / ㎥; fine aggregate 1,150~1,350 kg/m3; 50 to 60 wt% of water-binding material; And, by controlling the surface tension of the mixture of the mixing water, water reducing agent and shrinkage reducing agent at 20 ° C, the drying shrinkage on the 28th day is 600 με or less, and the mortar flow 250 ± 30 mm standard is satisfied. A wet self-filling mortar composition” is provided.

Description

Plastering omitable wet self-filling mortar composition for flooring

The present invention relates to a wet self-filling mortar composition for spraying, which can improve performance such as fluidity and shrinkage reduction effect, thereby omitting a plastering process and finishing the surface only with a paste.

Currently, mortar for plastering the floor of apartment houses (hereinafter 'Bangtong') is divided into dry and wet types.

Dry mortar is a powder that is integrated by mixing cement, fine aggregate, and other admixture materials, so-called dry mortar, and it is poured by mixing it with water at the construction site. In the case of a large number of households, such as apartments or large buildings, it is advantageous to pour with dry mortar in terms of construction, but problems such as uneven quality due to on-site water, excessive cracking, and the necessity of securing a working space due to the introduction of silos into the site there is.

Wet mortar is used where the amount of pouring is relatively small, such as small houses and commercial buildings, and mortar with a volume ratio of cement and fine aggregate of 1:3 is used. The quality of wet mortar is constant, but there is a problem of slump loss due to the adjustment of the dispatch interval or the addition of transportation time.

However, a bigger problem than the above problems is the occurrence of cracks due to shrinkage.

Cracks in floor mortar are largely divided into plastic shrinkage cracks and dry shrinkage cracks. Plastic shrinkage is a crack that occurs within the first 1 to 3 days after casting. To prevent this, install a windbreak before placing and perform plastering at least three times Plastering work is carried out three or more times not only for the purpose of preventing cracks due to plastic shrinkage, but also for the purpose of flattening the floor.

Drying shrinkage occurs at least one month after placement. There are ways to prevent drying shrinkage cracks by wire mesh, reinforcement around the right angle, etc., but it is difficult to prevent cracks due to this because the mortar itself has a large number of mixing.

1. Registered Patent No. 10-2404076 "Admixture for anti-ballistic mortar and anti-ballistic mortar composition containing the same" 2. Registered Patent No. 10-2259777 "Shrinkage Reducing Admixture and Unreinforced Concrete Composition for Indoor Parking Lot Floors" 3. Registered Patent No. 10-2468029 "Ultra-low shrinkage concrete composition with expansion control technology using SO3 and surface tension control technology using shrinkage reducing agent"

An object of the present invention is to provide a wet self-filling mortar composition for spraying, which can omit a plastering process and finish the surface only with a paste, by improving performance such as fluidity and shrinkage reduction, based on the existing wet mortar.

In order to solve the above problems, the present invention is a mortar composition having a design standard strength of 21 MPa or more, including a binder, fine aggregate, mixing water, water reducing agent and shrinkage reducing agent, binder amount 500 ~ 600 kg / ㎥; fine aggregate 1,150~1,350 kg/m3; 50 to 60 wt% of water-binding material; And, by controlling the surface tension of the mixture of the mixing water, water reducing agent and shrinkage reducing agent at 20 ° C, the drying shrinkage on the 28th day is 600 με or less, and the mortar flow 250 ± 30 mm standard is satisfied Plastering process, characterized in that A wet self-filling mortar composition for spraying that can be omitted” is provided.

The surface tension of the mixed solution at 20° C. can be controlled to 58.7 mN/m or less.

A premix of 60 to 90 wt% of type 1 ordinary Portland cement (OPC) and 10 to 40 wt% of fly ash (FA) may be applied to the binder, and some of the fly ash (FA) is blast furnace slag fine powder (SP) ) can be replaced with

Preferably, the binder may be premixed with 50 wt% of OPC, 45 wt% of FA, and 5 wt% of SP.

The fine aggregate may be crushed quarry sand, having a granulation rate of 3.0 to 3.1, a 0.08 mm sieve passing rate of 2.0 to 2.5, and an absorption rate of 1.2 to 1.5%.

In addition, 50 vol% or less of the fine aggregate (excluding 0 vol%) is replaced with washing sand, but the washing sand has a coarseness of 2.0 or less, a 0.08 mm sieve passing rate of 3.0 to 3.5, and an absorption rate of 1.2 to 1.5%.

The water reducing agent is a polycarboxylic acid type and is added in an amount of 0.5 to 1.0 wt% relative to the binder, and the shrinkage reducing agent is a glycol type and may be added in an amount of 1.0 to 2.0 wt% relative to the binder.

According to the present invention, a wet self-filling mortar composition for spraying with excellent fluidity and shrinkage reduction performance is derived, and by using the wet self-filling mortar composition for spraying provided by the present invention, the plastering work after curing can be completed only once. can This is because bleeding is reduced due to the characteristics of the shrinkage-reducing composition, so there is relatively little bleeding on the surface of the mortar, and therefore, unlike general mortar, which requires plastering whenever bleeding occurs, the surface quality is excellent even with only one plastering.

The present invention relates to a wet self-filling mortar composition for spraying which can omit a plastering process and improves performance such as fluidity and shrinkage reduction based on existing wet mortar.

The present invention is a mortar composition having a design standard strength of 21 MPa or more, including binder, fine aggregate, mixing water, water reducing agent and shrinkage reducing agent, binder amount 500 ~ 600 kg / ㎥; fine aggregate 1,150~1,350 kg/m3; 50 to 60 wt% of water-binding material; And, by controlling the surface tension of the mixture of the mixing water, water reducing agent and shrinkage reducing agent at 20 ° C, the drying shrinkage on the 28th day is 600 με or less, and the mortar flow 250 ± 30 mm standard is satisfied Plastering process, characterized in that A wet self-filling mortar composition for spraying that can be omitted” is provided.

For the binder, a premix of 60 to 90 wt% of type 1 ordinary Portland cement (OPC) and 10 to 40 wt% of fly ash (FA) may be applied, and the fine aggregate is crushed quarry sand, with a fineness of 3.0 to 3.1 and 0.08. A millimeter sieve passing rate of 2.0 to 2.5 and water absorption of 1.2 to 1.5% can be applied.

The water reducing agent may be added in an amount of 2.5 to 5 kg/m3 as a polycarboxylic acid type, and the shrinkage reducing agent may be added in an amount of 6 to 9.6 kg/m3 as an ethylene glycol type.

Hereinafter, the present invention will be described in detail according to the performance comparison test results of the present invention and existing mortar products, the tests performed in the process of deriving the present invention, and the analysis process.

I. Basic physical properties (compressive strength and mortar flow) test

1. Test plan and materials used

1.1 Test plan

[Table 1] summarizes the test items for each type of anti-ballistic mortar.

'Dry mortar' and 'wet mortar' shown in [Table 1] are selected from among commonly used products, and 'developed products' are examples of mortar products derived from the present invention.

[Table 2] summarizes the test factors and test items for unit quantity selection and washing company review.

[Table 3] summarizes test factors and test items for comparative review of admixtures (dispersants).

[Table 4] summarizes test factors and test items for comparative review of sand by production area.

[Table 5] summarizes the test factors and test items for selecting the binder ratio.

1.2 Materials used

(1) sand

A total of 9 types of sand were used in this study, and their physical properties are shown in [Table 6].

(2) Cement

The cement used in this study was a type 1 ordinary Portland cement, and its physical properties are shown in [Table 7].

(3) admixture

Fly ash and blast furnace slag fine powder were reviewed as admixtures, and their physical and chemical properties are shown in [Table 8] (fly ash) and [Table 9] (blast furnace slag fine powder).

2. Test results and considerations

2.1 Comparison of anti-ballistic mortar products

In this study, we tried to compare the dry mortar actually produced with the wet mortar produced from ready-mixed concrete and three types of developed products. First, in the case of mixing, water was added until material separation did not occur and high fluidity was obtained, and an admixture used for each product was used as a water reducing agent. A polycarboxylic acid-based water reducing agent was added to the developed product, and shrinkage reducing agents were not considered in this test step.

W: mixing water W/B: water binder ratio

OPC: Class 1 ordinary Portland cement F/A: Fly ash

S/P: Fine powder of blast furnace slag LSP: Gypsum

S: sand AD: water reducing agent

[Table 11] shows the results of the fluidity performance of each pouring mortar. First, in terms of flow, the developed product showed the best fluidity performance, and the dry mortar showed the lowest flow at 200 mm. In addition, in the J-lot, which simply evaluates the viscosity of mortar, wet mortar and developed products showed good results, but dry mortar did not pass due to high viscosity. Bleeding, which has the greatest influence on the surface finish and setting time of the anti-fouling mortar, was also found to be significantly better than the dry and wet mortars.

Therefore, it can be seen that the developed product has better overall physical properties than other mortars.

2.2 Unit quantity selection and cleaning company review

In this study, we tried to find out how the flowability according to the increase in the unit quantity of mortar and the change in the physical properties of the mortar when mixed with the washing sand were affected. At this time, the mixing details are shown in [Table 12], and the test results are shown in [Table 13]. In the case of mixing with washing sand, only the level of 270 kg / ㎥ of unit water (water-binder ratio 45 wt%) was reviewed.

CS: crushed sand SS: washing sand

[Picture 1] below shows the flow test results for each formulation.

[Picture 1]

First, when examining the physical properties of each unit quantity, in the case of a unit quantity of 240 kg/m3, mixing was difficult as shown in (1) of [Picture 1] at 0.70 wt% of the water reducing agent (weight ratio to binder, the same below), and 0.75 wt% In %, material separation occurred as shown in the picture (2). At a unit quantity of 270 kg/m3, it was found that the target flow was satisfied as shown in the photo (3) at the level of 0.50 wt% of the water reducing agent.

In the case of a unit quantity of 300 kg / ㎥, low fluidity was exhibited as shown in the photo (4) at 0.30 wt% of the water reducing agent used, and material separation occurred as shown in the photo (5) at 0.40 wt%. In this way, it was found that the wet mortar for spraying is very sensitive to the unit quantity and the amount of the water reducing agent, and accordingly, it is judged that it is important to match the appropriate unit quantity.

When examining the blending of washing sand at a unit quantity of 270 kg / ㎥, when 50 vol% of washing sand (volume ratio relative to the total sand, hereinafter the same) is mixed, the target flow as shown in the photo (6) at 0.45 wt% of water reducing agent was not satisfied, and at 0.60 wt%, the J-lot flow time increased compared to the W 270-CS 100% test specimen, and the viscosity increased slightly, but the target flow was found to be satisfied.

In the case of 100 wt% of washing sand, mixing is difficult as shown in the photo (8) with the amount of water reducing agent at the level of 0.7 wt%, and mixing is possible only when 0.9 wt% of water reducing agent is added. It was found that material segregation occurred. Therefore, it is considered that it is preferable to use the washing sand in the range of 50 vol% or less. In the range of 50 vol% or less, it is considered to be helpful in stabilizing physical properties (reducing deviation in physical properties) due to the increase in viscosity when the washing sand is incorporated.

2.3 Comparative review of sand by production area

In this study, a total of 8 types of 4 types of stone ash and 4 types of blasting stones were compared and reviewed to find out how the use of sand for each production area of stone ash and blasting stone affects the overall physical properties of wet mortar for fire protection. The mixing details for the test are shown in [Table 14], and the test results are shown in [Table 15].

In this test, the formulation was designed to satisfy the target flow by adding additional water and increasing the amount of water reducing agent. Here, the flow measurement was measured from 0 minutes to the flow after 60 minutes in order to examine the retention performance of the admixture.

[Graph 1] is a graph showing the flow by sand origin. First of all, the mixture using crushed sand obtained from quarries showed good fluidity overall, and the mixture using crushed sand obtained from blasting stone showed relatively low fluidity despite the addition of water. This is considered to be due to a combination of causes such as high soil content and poor particle size when blasting stone sand was used, which adversely affected the overall physical properties of the mortar.

In the case of flow maintenance performance, the mixture using C sand showed the best results, and about 10 mm of flow loss occurred after 60 minutes. However, in terms of bleeding rate, on the contrary, the mixture using C sand was measured the highest.

[Graph 1]

[Graph 2] is a graph showing the compressive strength by sand origin. Overall, the mixture using crushed sand obtained from quarries showed high strength and showed a similar trend to flow. Among the quarry sands, the mixture using A sand and D sand was found to exert more than 25 MPa at 28 days of age, and the highest strength was exhibited when using A sand in 1 day strength. Mixture using blasting stone exhibited a low strength of around 15 MPa even at 28 days of age, which is considered to be the result of poor particle size, excessive soil content and increase in unit yield, as analyzed in the flow above.

Therefore, as a result of the comprehensive analysis, it was judged that the mixture using quarry sand could reduce the amount of unit and the amount of admixture compared to the mixture using blasting stone, and the mixture using sand A among quarry mountains was found to have the best overall physical properties.

[Graph 2]

2.4 Selection of binder ratio

In this study, the general physical properties of mortar, such as fluidity and strength, were compared and reviewed according to the binder type and ratio.

[Graph 3] is a graph showing the flow according to the binder ratio. First, in the case of the two-component mixture without S/P, the flow was about 240 mm, which was about 10 mm lower than that of the three-component mixture with S/P. In addition, in the case of the two-component mixture, a large flow loss occurred after 60 minutes or a case in which the fluidity increased at all.

On the other hand, it can be seen that the ternary mixture containing both F/A and S/P maintains fluidity after 60 minutes or increases and decreases in a small width. Accordingly, it was judged that the three-component mixture was more advantageous in fluidity and retention performance than the two-component mixture.

[Graph 3]

[Graph 4] is a graph showing the compressive strength by age according to the binder ratio. As with the flow, the mixture using F/A and S/P showed high compressive strength overall, and the strength of No. 4 mixture, which replaced a small amount of S/P, was greatly improved rather than the No. 3 mixture, which had a high cement ratio. appear. This is thought to be due to the pozzolanic reaction of F/A and the latent hydraulic reaction of S/P.

Overall, it is analyzed that the three-component mixture using up to S/P is more advantageous in terms of fluidity and strength than the two-component mixture using only OPC and F/A. It is judged that the physical properties of the mortar mixture with the binder ratio are the best.

[Graph 4]

2.5 Other arrangements

In addition to the above test contents, the results of research conducted to develop a wet self-filling mortar for anti-fouling that can improve fluidity and crack reduction performance based on conventional wet mortar and omit the plastering process and finish the surface only with pus can be summarized. As follows.

1) Since the unit quantity plays a large role in fluidity and viscosity control in wet mortar for blasting, it shows the best physical properties such as fluidity, strength and durability when the quantity is appropriate. As a result of the study, the optimal water-binder ratio was found to be 50~60 wt%.

2) Polycarboxylic acid-based water reducing agent shows excellent performance in improving fluidity and reducing unit quantity in wet mortar for blasting, and it is appropriate to add 0.5 to 1.0 wt% compared to binder in terms of performance and economy.

3) Mortar flow 250±30 mm, age 28 under conditions of binder amount 500~600 kg/㎥, fine aggregate amount 1,150~1,350 kg/㎥, water-binder ratio 50~60 wt%, and water reducing agent 0.5~1.0 wt% added to binder Physical properties of work compressive strength of 21 MPa or more are secured.

4) The addition of a shrinkage reducing agent causes a change in the physical properties of mortar, and the specific test contents regarding this are explained as in the section "II. Drying Shrinkage Test" below.

II. Drying shrinkage test

1. Review of shrinkage reducing agent content

[Table 18] below is a formulation table of examples of the present invention, and [Table 19] shows the basic physical properties of [Table 18] formulation examples.

AD: polycarboxylic acid water reducing agent

SRA: Ethylene glycol-based shrinkage reducing agent

[Graph 5] below changes the content of the shrinkage reducing agent (SRA) in the above [Table 18] formulation (increased by 0.5 wt% from 0.5 wt% to 2.0 wt% compared to the composite material), and the length at 28 days and 77 days [Table 20] shows the comparison of the shrinkage reduction rate compared to the test specimen (Plain) without the addition of the shrinkage reducing agent.

[Graph 5]

As compared to the Plain test specimens, the drying shrinkage length change decreases as the amount of shrinkage reducing agent is increased, but the shrinkage reduction rate increases significantly up to SRA 1.5% specimens, while the length change reduction width decreases slightly in SRA 2.0% specimens. was However, since the shrinkage reduction rate of the SRA 0.5% test specimen compared to Plain is not as high as less than 10%, and the shrinkage reduction effect is rapidly improved in the range of SRA 0.5% specimen to SRA 1.0% specimen, it is recommended that the shrinkage reducing agent content be set at 1.0 wt% or more compared to the binder. judged to be desirable.

[Graph 6] and [Table 21] below show the change in compressive strength by the amount of shrinkage reducing agent (SRA).

[Graph 6]

Plain test specimens up to SRA 1.5% specimens had almost the same compressive strength by age, but the compressive strength tended to decrease rapidly in SRA 2.0% specimens. However, the SRA 2.0% test specimen also satisfies the design standard strength 21 MPa condition, so it is considered desirable to control the shrinkage reducing agent content within 2.0 wt% compared to the binder.

2. Examination of the surface tension of the mixed solution (mixing water, water reducing agent and shrinkage reducing agent)

Since drying shrinkage is a phenomenon in which shrinkage occurs as the moisture inside the mortar evaporates, reducing the surface tension of the moisture inside the pores of the mortar can reduce the amount of drying shrinkage and lower the probability of cracking in the long term.

Accordingly, glycols such as PEG (Polyethylene Glycol), HG (Hexylene Glycol), and BDG (Butyl Di Glycol) as shown in [Reference Figure 1] are applied as shrinkage reducing agents (SRA) of the concrete composition. It is possible to reduce the surface tension acting in the direction of shrinking the liquid. As shown in [Reference 2] below, according to the action of the shrinkage reducing agent (SRA), the surface tension (γ) of moisture contained in the pores of the concrete decreases, and the radius of curvature (r _n : Radius of Curvature of Liquid Surface ) is increased, and as a result, the capillary tension (ΔP: Capillary Tension) calculated as γ (1/r _n ) is reduced and the shrinkage is reduced.

[Reference Figure 1]

[Reference Figure 2]

Therefore, the correlation between the drying shrinkage amount according to the progress of mortar hardening and the surface tension measurement value of the mixing water, shrinkage reducing agent and water reducing agent mixture was reviewed through regression analysis for each amount of shrinkage reducing agent (SRA) added.

[Table 22] below shows the surface tension of the mixture water, water reducing agent (AD) and shrinkage reducing agent (SRA) mixture. As the water reducing agent (AD), a polycarboxylic acid-based water reducing agent containing 17 wt% of solid content was applied, and as a shrinkage reducing agent (SRA), HG (Hexylene Glycol) having a surface tension of 33.1 mN/m based on 20 ° C was applied.

[Table 23] shows the drying shrinkage for each specimen at 28 days of age and the surface tension of the mixed solution (at 20 ° C), [Graph 7] shows the drying shrinkage according to the amount of shrinkage reducer (SRA), [Graph 8] It is a graph showing the amount of drying shrinkage according to surface tension, respectively.

[Graph 7]

[Graph 8]

In the above test, the drying shrinkage of the Plain specimen at 28 days of age is 795 με, so if the drying shrinkage is about 600 με at the same age, the drying shrinkage rate is about 25%, which shows a significant shrinkage reduction effect.

By controlling the surface tension of the mixture at 20 ° C, the drying shrinkage at 28 days of age can be 600 με or less. performance is expressed.

In addition, the surface tension of the mixture can be set according to the regression analysis formula [Equation 1] below so that the drying shrinkage at 28 days of age is 600 με or less. According to [Equation 1], when the surface tension of the mixed solution at 20 ° C is 58.7 mN / m or less, the drying shrinkage at 28 days of age is 600 με or less.

[Equation 1]

y = 26.21x - 938.55

As a result of the regression analysis of the shrinkage reduction according to the surface tension of the mixed solution in the concrete reviewed in Patent No. 10-2468029 and the mortar according to the present invention, the slope of the regression analysis graph was about 8.9 in concrete, while it was high at 26.2 in mortar. In the unit weight mixing, the mixing water content of mortar is higher than that of concrete, and accordingly, it is judged that the effect of the shrinkage reducing agent is greater.

In general, it is recommended to carry out plastering work at least 3 to 4 times after pouring the floor mortar. However, as the wet self-filling mortar composition for blasting provided by the present invention is used, the work can be completed only with high quality.

This is because bleeding is reduced due to the characteristics of the shrinkage-reducing composition, so there is relatively little bleeding on the surface of the mortar, and therefore, unlike general mortar, which requires plastering whenever bleeding occurs, the surface quality is excellent even if it is smoothed.

[Reference Figure 3]

[Table 24] below summarizes the physical properties of the present invention compared to existing products, and [Reference Figure 4] compares the minimum shrinkage reduction effect and bleeding reduction effect according to the present invention with other products, [Reference Figure 5] is a photograph showing the effect of improving workability and improving cracks on the floor surface according to the use of the product of the present invention.

[Reference Figure 4]

[Reference Figure 5]

In the above, the present invention was examined in detail with specific test examples. However, the present invention is not limited by the above embodiments and can be modified and modified within the scope without departing from the gist of the present invention. Accordingly, the claims of the present invention include such modifications and variations.

Claims (8)

A mortar composition with a design standard strength of 21 MPa or more, including binder, fine aggregate, mixing water, water reducing agent and shrinkage reducing agent,
Bonding material 500~600 kg/㎥; fine aggregate 1,150~1,350 kg/㎥; Water-binder ratio 50-60 wt%; ego,
The water reducing agent is a polycarboxylic acid system and is added in an amount of 0.5 to 1.0 wt% compared to the binder,
The shrinkage reducing agent is glycol-based and is added in an amount of 1.0 to 2.0 wt% compared to the binder,
According to the following [Equation 1], the surface tension of the mixture of the mixing water, the water reducing agent and the shrinkage reducing agent is controlled to 58.7 mN / m or less at 20 ° C, so that the drying shrinkage on the 28th is 600 με or less,
A wet self-filling mortar composition for spraying that can omit the plastering process, characterized in that the mortar flow 250 ± 30 mm standard is met.
[Equation 1]
y = 26.21x - 938.55
x: Surface tension (mN/m) of mixing water, water reducing agent and shrinkage reducing agent mixture at 20℃
y: Drying shrinkage at 28 days of age (με) of the mortar composition
delete In paragraph 1,
The binder is a wet self-filling mortar composition for spraying that can be omitted from the plastering process, characterized in that 60 to 90 wt% of one type ordinary Portland cement (OPC) and 10 to 40 wt% of fly ash (FA) are premixed.
In paragraph 3,
Wet self-filling mortar composition for blasting, characterized in that premixed by substituting a part of the fly ash (FA) with blast furnace slag fine powder (SP).
In paragraph 4,
The binder is a wet self-filling mortar composition for spraying that can be omitted from the plastering process, characterized in that OPC 50 wt%, FA 45 wt% and SP 5 wt% are premixed.
In paragraph 1,
The fine aggregate is crushed quarry sand, has a granulation rate of 3.0 to 3.1, a 0.08 mm sieve pass rate of 2.0 to 2.5, and an absorption rate of 1.2 to 1.5%.
In paragraph 6,
Replace 50 vol% or less (excluding 0 vol%) of the fine aggregate with washing sand,
The washing sand has a granulation rate of 2.0 or less, a 0.08 mm sieve pass rate of 3.0 to 3.5, and an absorption rate of 1.2 to 1.5%.
delete