KR102153631B1 - Rapid hardening cement composition, modified concrete composition comprising the same and road pavement method using the same - Google Patents

Abstract

The present invention relates to an ultra-rapid-hardening cement composition capable of reducing the occurrence of cracks while exhibiting ultra-rapid-hardening properties, a modified concrete composition comprising the same, and a road pavement method using the same. The present invention provides the ultra-rapid-hardening cement composition comprising: 50-60 wt% of OPC; 20-30 wt% of CSA with fineness of 5,000 m^2/g or more; 10-20 wt% of anhydrous gypsum with fineness of 6,000 m^2/g or more; 2.0-15 wt% of alumina cement; 0.5-5.0 wt% of calcium hydroxide; 0.1-3.0 wt% of a curing accelerator; 0.1-2.0 wt% of a tartaric acid hardening retardant; 0.1-2.0 wt% of a polycarboxylic acid-based high-performance water-reducing agent; 0.1-1.0 wt% of a fatty acid-based antifoamer; 1.0-3.0 wt% of a crosslinked shrinkage reducing agent; and 1.0-3.0 wt% of a strength enhancer. Also, the present invention provides the modified concrete composition, which comprises: 350-380 kg/m^3 of the ultra-rapid-hardening cement composition; 850-1,000 kg/m^3 of fine aggregates; 750-950 kg/m^3 of coarse aggregates; and 110-120 kg/m^3 of a latex solution, is added with 0.4-0.6 wt% of a citric acid hardening retardant compared to the ultra-rapid-hardening cement composition, and is characterized by 35-40 wt% of a water cement ratio and 50-60 vol% of fine aggregates. The present invention also provides a pavement method thereof.

Description

Super fast-hardening cement composition, modified concrete composition containing the same, and road pavement method using the same {RAPID HARDENING CEMENT COMPOSITION, MODIFIED CONCRETE COMPOSITION COMPRISING THE SAME AND ROAD PAVEMENT METHOD USING THE SAME}

The present invention relates to an ultra-fast-hardening cement composition capable of reducing the occurrence of cracks while exhibiting super-fast-hardness, a modified concrete composition including the same, and a road pavement method using the same.

Road pavement is mainly made of asphalt concrete or cement concrete. There are advantages and disadvantages between the two, but since asphalt concrete has durability problems such as pop-out, cement concrete is often required for road pavement.

When cement concrete is used, the cost of road pavement is increased, but it is excellent in terms of durability. In particular, in the case of road pavement repair work, since rapid traffic opening is required in terms of traffic flow, the construction time can be shortened by applying ultra-fast cement. The Korea Expressway Corporation sets the standard for a road traffic opening condition with a compressive strength of 21 MPa or more, and efforts to meet the above criteria in the shortest period are continuing, and Patent Registration 10-1019073 compresses more than 21 MPa within 24 hours. Latex-modified concrete that exhibits strength is proposed.

However, in the section with heavy traffic, traffic control for 24 hours also causes a lot of problems, so it is necessary to start work after midnight when the traffic volume is least and open the traffic until the rush hour when traffic volume increases. It is necessary to improve the problem that the durability of the cement-concrete pavement layer to which is applied is shorter than the expected life.

1. Registered Patent No. 10-1019073 "Super crude steel cement and latex modified concrete composition using the same" 2. Registered Patent No. 10-1366062 "Concrete composition for paving bridges and its manufacturing method" 3. Registered Patent No. 10-0943312 "Super-fast cement concrete composition and concrete pavement repair method using the same" 4. Registered Patent No. 10-1536118 "Super fast-hardening cement composition and its manufacturing method"

An object of the present invention is to provide an ultra-fast-diameter cement composition, a modified concrete composition including the same, and a road pavement method using the same, and to improve durability by suppressing dry shrinkage cracks while expressing a compressive strength of 21 MPa or more based on 4 hours of age. have.

In order to solve the above problems, the present invention is "OPC 50 ~ 60wt%; 20 to 30 wt% of CSA with a powderiness of 5,000 m 2 /g or more; 10-20wt% of anhydrous gypsum having a powderiness of 6,000㎡/g or more; 2.0-15 wt% of alumina cement; 0.5 to 5.0 wt% of calcium hydroxide; 0.1~3.0wt% of curing accelerator; 0.1~2.0wt% of tartaric acid hardening retardant; 0.1 to 2.0 wt% of a polycarboxylic acid-based high-performance water reducing agent; 0.1 to 1.0 wt% of fatty acid-based antifoam; 1.0 to 3.0 wt% of a crosslinked shrinkage reducing agent; And 1.0 to 3.0 wt% of a strength enhancer; It provides an ultra-fast diameter cement composition" containing.

The crosslink type shrinkage reducing agent (C ₆ H ₅ CH=CH ₂ ) _n SiO compound, n being 2 or more, can be applied, and the strength enhancer is an alkali metal bonded sulfate compound, an alkali metal The content is 50-60wt%, and a pH of 2-5 can be applied.

In addition, the present invention "the super-fast cement composition 350 ~ 380kg / ㎥; Fine aggregate 850~1,000kg/㎥; Coarse aggregate 750~950kg/㎥; And latex solution 110-120kg/m3; Including, citric acid hardening retardant is added 0.4 ~ 0.6wt% compared to the ultrafast cement composition, water cement ratio 35 ~ 40wt%; Fine aggregate ratio 50~60vol%; A modified concrete composition characterized in that it is provided together.

The present invention relates to “(a) preparing a modified concrete composition by measuring and mixing the ultra-fast cement composition, fine aggregate, coarse aggregate, latex solution, and citric acid hardening retardant delivered to the construction site; (b) forming a road surface by laying the modified concrete composition along the work surface; And (c) smoothing the road surface with a trowel while compacting the road surface by rolling. Road pavement method including ”is provided together.

When the ultra-fast cement composition provided by the present invention and the modified concrete composition using the same are applied to road pavement, a compressive strength of 21 MPa or more is expressed for 4 hours, so that construction can be started after midnight and the road can be opened within 4 hours, It is possible to build a road pavement with improved durability by solving the problem of cracking that has been pointed out when using conventional super-fast cement.

The present invention provides an ultrafast cement composition and a modified concrete composition using the same.

Ultrafast cement composition provided by the present invention is OPC 50 ~ 60wt%; 20 to 30 wt% of CSA with a powderiness of 5,000 m 2 /g or more; 10-20wt% of anhydrous gypsum having a powderiness of 6,000㎡/g or more; 2.0-15 wt% of alumina cement; 0.5 to 5.0 wt% of calcium hydroxide; 0.1~3.0wt% of curing accelerator; 0.1~2.0wt% of tartaric acid hardening retardant; 0.1 to 2.0 wt% of a polycarboxylic acid-based high-performance water reducing agent; 0.1 to 1.0 wt% of fatty acid-based antifoam; 1.0 to 3.0 wt% of a crosslinked shrinkage reducing agent; And 1.0 to 3.0 wt% of a strength enhancer; It is composed including.

The present invention utilizes the rapid setting of Calcium Sulfo-Aluminate (CSA) of 5,000 m²/g or more in powder, but stably exhibits durability based on OPC (Ordinary Portland Cement), and anhydrous gypsum of 6,000 m²/g or more in powder By mixing calcium hydroxide (slaked lime, Ca(OH) ₂ ), the amount of ettringite produced is increased and the production rate is improved, so that the pores formed by the rapid setting of the CSA are filled. In addition, by mixing the alumina cement, the reaction rate of CSA blunted by the anhydride is again promoted and the reaction rate of CSA is improved in low temperature conditions.

The OPC, CSA, anhydrous gypsum, calcium aluminate, and calcium hydroxide may be relatively determined within the above-described content range, and the actions and effects of each component are known, and thus detailed descriptions thereof will be omitted.

The curing accelerator is an admixture that improves initial compressive strength by shortening the setting time of the super-fast-hardening cement composition of the present invention, and calcium chloride, magnesium chloride, etc. can be applied, in the range of 0.1 to 3.0 wt% of the super-fast-hardening cement composition of the present invention. Is added.

However, in the present invention, a tartaric acid curing retardant is added together with the curing accelerator to secure a working time of about 30 minutes. The curing accelerator may change in performance depending on the temperature condition of the work site, the temperature condition of the mixing water, etc., but by applying the tartaric acid curing delay agent, an initial setting time of 30 minutes can be stably secured. The tartaric acid hardening retardant is added in the range of 0.1 to 2.0wt% of the ultrafast cement composition of the present invention.

Polycarboxylic acid-based high-performance water reducing agent is an admixture that improves fluidity and workability by increasing the dispersibility of cement particles, and is added in the range of 0.1 to 2.0 wt% of the ultrafast cement composition of the present invention.

The fatty acid-based antifoaming agent is an admixture that improves durability by removing entrapped air in concrete, and is added in the range of 0.1 to 1.0 wt% of the ultrafast cement composition of the present invention.

The crosslinked shrinkage reducing agent is an admixture for reducing the drying shrinkage of concrete, and is added in the range of 1.0 to 3.0wt% of the ultrafast cement composition of the present invention. The crosslink type shrinkage reducing agent is a styrene silicate ((C ₆ H ₅ CH=CH ₂ ) _n SiO) compound, wherein n is 2 or more and has a silicate bond structure. The crosslinked shrinkage reducing agent forms a chain-shaped network between the shrinkage reducing agent and the aggregate and the binder by a hydration reaction. This chain-shaped network reduces the shrinkage phenomenon by mitigating the capillary tension that occurs when water evaporates in the pores of 2.5-50nm size, which have the greatest effect on drying shrinkage.

The strength enhancer is an admixture that accelerates the initial hydration reaction of cement due to alkali stimulation and prevents delay in curing, and is added in the range of 1.0 to 3.0 wt% of the ultrafast cement composition of the present invention. The strength enhancer is an alkali metal-bonded sulfate compound, with an alkali metal content of 50 to 60 wt% and a pH of 2 to 5, and Al ₂ O ₃ -SiO ₂ or CaO-Al ₂ O ₃ -SiO ₂ Initial strength can be promoted by accelerating the reaction of the system binder.

The modified concrete composition provided by the present invention includes the above-described ultra-fast cement composition (hereinafter referred to as'binder') 350-380kg/㎥; Fine aggregate 850~1,000kg/㎥; Coarse aggregate 750~950kg/㎥; And latex solution 110-120kg/m3; It is composed of, citric acid hardening retardant is added 0.4 ~ 0.6wt% compared to the ultrafast cement composition, water cement ratio 35 ~ 40wt%; Fine aggregate ratio 50~60vol%; Is.

Hereinafter, the present invention will be described with specific test results.

[Table 1] is a blending table of an example of the modified concrete composition of the present invention. Per unit volume of 1㎥, 360kg of binder (B), 918kg of fine aggregate (S), 766kg of coarse aggregate (G), and 115kg of latex solution were mixed, and 76kg of water was mixed, but the water of the latex solution (water in the latex solution Silver 45~55wt%, water in the latex solution used in the following formulation was added to 52.87wt%) so that the water binding material ratio was 38wt%. The fine aggregate ratio is 55vol%.

W/B
(wt%) S/a
(vol%) Citric acid hardening retardant
(B×wt%) Unit dimensional weight (kg/㎥) W B S G Latex 38 55 0.5 76 360 918 766 115

[Table 2] below summarizes the results of the rheological properties test of concrete according to the contents of the strength enhancer (Cl) and the crosslinked shrinkage reducing agent (SR) in the binder (B).

division Slump (mm) Air volume (vol%) Comparative example Plain 195 4.7 Example 1 Cl 1wt% + SR 1wt% 190 4.3 Example 2 Cl 1wt% + SR 3wt% 190 4.5 Example 3 Cl 3wt% + SR 3wt% 195 4.2

As shown in [Table 2] above, since there is no clear tendency to change in the amount of slump and air depending on the content of the strength enhancer (Cl) and crosslinked shrinkage reducing agent (SR), the strength enhancer (Cl) and shrinkage reduction It is evaluated that the influence of the agent (SR) on the rheological properties of concrete is insignificant.

[Table 3] and [Graph 1] below summarize the results of the compressive strength expression characteristic test results for each age according to the strength enhancer (Cl) content in the binder (B). The crosslinked shrinkage reducing agent (SR) was not a factor affecting the expression of compressive strength, but was tested while only changing the content of the strength enhancer (Cl) in a state in which 1 wt% was included in the binder.

division Age 4 hours (MPa) Age 28 days (MPa) Comparative example Plain 19.2 49.8 Example 1 Cl 1wt% 23.9 51.9 Example 4 Cl 2wt% 25.3 52.2 Example 5 Cl 3wt% 27.1 52.1

[Graph 1]

Since the target performance was over 21 MPa for 4 hours of age and 30 MPa for 28 days of age, the compressive strength target of 28 days of age was satisfied in both Comparative Examples and Examples, but in the case of Comparative Example, the compression strength target of 4 hours of age was not achieved.

Examples 1, 4, 5 showed that the compressive strength of 4 hours was improved according to the increase in the amount of the strength enhancer (Cl) mixed, but in the long-term age (28 days of age), the strength was improved from Example 5 to Example 4 Since there was no effect, the appropriate content of the strength enhancer is evaluated to be 1 to 3 wt% of the binder in consideration of target performance and economy.

[Graph 2] below shows the results of the dry shrinkage test according to the content of the crosslinked shrinkage reducing agent (SR) in the binder (B). The strength enhancer (Cl) is not a factor that affects the amount of dry shrinkage, but compared to Comparative Examples (Plain) in Examples 1 and 2 in which only the content of the crosslinked shrinkage reducing agent (SR) was changed in a state in which 1 wt% was included in the binder. And showed.

[Graph 2]

In the case of the comparative example (Plain) without the addition of the crosslinked shrinkage reducing agent (SR), the amount of shrinkage increased immediately after pouring, and as shown in [Reference Photo 1] below, the mock-up test result A number of cracks occurred.

[Reference photo 1]

When the crosslinking type shrinkage reducing agent (SR) was added, the shrinkage amount reached almost 0 until 7 days of age, and as a result of the mock-up test using Example 1, cracks did not occur as shown in [Reference Photo 2] below. Did.

[Reference photo 2]

[Table 4] below shows a comprehensive test of the concrete properties expressed by Example 2 above. The following test standards are the quality standards required by Korea Expressway Corporation, and Example 2 was found to satisfy all the required test standards.

division Test result Test standard Slump (mm) 190 190±30 Air volume (vol%) 4.5 3.0~6.0 Compressive strength Based on opening hours (4 hours) 26 21 or more 28 days 51.5 Over 30 Chlorine ion penetration resistance (c) 28 days 282 1,000 or less Freeze-thaw resistance (%) 28 days 92 80 or more Crack resistance 56 days No cracks No cracks until 56 days of age Wear resistance (mm) 0.13 2 or less Adhesion strength Based on opening hours (4 hours) 1.6 1.4 or higher Dry shrinkage (%) 7 days 0.017 0.15 or less Coefficient of thermal expansion (/℃) 7 days 11.76×10 ^-6 4~20×10 ^-6 Modulus of elasticity (MPa) 7 days 28,954 11,300~78,000

In addition, the present invention "(a) the step of manufacturing a modified concrete composition by metering and mixing the ultra-fast cement composition, fine aggregate, coarse aggregate, latex solution and citric acid hardening retardant transported to the construction site; (b) forming a road surface by laying the modified concrete composition along the work surface; And (c) smoothing the road surface with a trowel while compacting the road surface by rolling. Road pavement method including ”is provided together.

Step (a) is a modified concrete manufacturing step. As described above, the modified concrete composition is mixed in the range of 350-380kg/㎥, fine aggregate 850-1,000kg/㎥, coarse aggregate 750-950kg/㎥, and latex solution 110-120kg/㎥ as described above, and water cement ratio Mix water so that it becomes 35-40wt%. The fine aggregate ratio is set to be 50 to 60 vol%, and a citric acid hardening retardant is added in the range of 0.4 to 0.6 wt% compared to the ultrafast cement composition according to the temperature conditions of the construction site.

The step (b) is a modified concrete laying step. In this step, by using a mixing-laying equipment that performs mixing and laying of concrete raw materials together, the operation of flattening while pouring the modified concrete along the work target surface can be continuously performed.

The step (c) is a compaction and smoothing step, wherein the road surface laid by the step (b) is compacted with a roller equipment, and the compacted surface is straightened by troweling.

Thereafter, if necessary, tinning can be performed, and in this case, by spraying a film curing agent on the rough-finished road surface, it is possible to suppress the occurrence of cracks in the road and to achieve stable strength development.

In the present invention, since the initial setting time of the modified concrete is also shortened by the fast setting of the super-fast-diameter cement composition, it is preferable to perform the tinning operation within 20 minutes, including the steps (a) to (c).

Although the physical properties and effects of the composition of the present invention were reviewed through the above examples, the present invention is not limited to the above embodiments, and some modifications and changes are made within the scope not departing from the technical spirit of the present invention. I would say it is possible.

Claims (5)

delete OPC 50-60wt%;
20 to 30 wt% of CSA with a powderiness of 5,000 m 2 /g or more;
10-20wt% of anhydrous gypsum having a powderiness of 6,000㎡/g or more;
2.0-15 wt% of alumina cement;
0.5 to 5.0 wt% of calcium hydroxide;
0.1~3.0wt% of curing accelerator;
0.1~2.0wt% of tartaric acid hardening retardant;
0.1 to 2.0 wt% of a polycarboxylic acid-based high-performance water reducing agent;
0.1 to 1.0 wt% of fatty acid-based antifoam;
Crosslink type shrinkage reducing agent 1.0~3.0wt%; And
1.0 to 3.0 wt% strength enhancer; Including,
The crosslinked shrinkage reducing agent (C ₆ H ₅ CH=CH ₂ ) _n SiO compound, wherein n is 2 or more.
In paragraph 2,
The strength enhancer is an alkali metal-bonded sulfate compound, wherein the alkali metal content is 50-60wt%, and the pH is 2-5.
350-380kg/㎥ of the ultra-fast-hard cement composition of claim 2 or 3;
Fine aggregate 900~950kg/㎥;
Coarse aggregate 750~800kg/㎥; And
Latex solution 110~120kg/㎥; Including,
Citric acid hardening retardant is added in 0.4 to 0.6 wt% compared to the ultrafast cement composition,
Water cement ratio 35-40wt%;
Fine aggregate ratio 50~60vol%; Modified concrete composition, characterized in that.
(a) preparing a modified concrete composition by measuring and mixing the ultra-fast cement composition of claim 2 or 3, fine aggregate, coarse aggregate, latex solution, and citric acid hardening retardant delivered to the construction site;
(b) forming a road surface by laying the modified concrete composition along the work surface; And
(c) smoothing the road surface with a trowel while compacting the road surface by rolling; Road pavement method including a.