KR102763473B1 - Eco-friendly water-permeable concrete for road pavement - Google Patents

Abstract

The invention relates to an environmentally friendly permeable concrete for road paving, which is formed by mixing 78 to 82 weight% of aggregate, 14 to 17 weight% of a stimulant, and 4 to 5 weight% of water through room temperature curing, wherein the stimulant is mixed in a ratio of 40 to 45 weight% of ordinary cement which secures the bonding strength of concrete; 5 to 10 weight% of ultra-rapid-setting cement which improves the rapid hardening ability of concrete; 5 to 11 weight% of silica which improves the workability and formability of concrete; 10 to 15 weight% of metakaolin which supplements the bonding strength of concrete; 5 to 10 weight% of anhydrite which improves the compressive strength of concrete; and 10 to 15 weight% of a solidifying agent which improves the permeability coefficient and void ratio of concrete to secure permeability.

Description

Eco-friendly water-permeable concrete for road pavement

The present invention relates to an eco-friendly permeable concrete for paving roads, parks, etc., and more specifically, to an eco-friendly permeable concrete for paving roads, which prevents roadway water pooling by allowing moisture to pass through, prevents ground weakening by evaporating ground moisture, reduces greenhouse gases by reducing cement use, and prevents water pollution caused by strongly alkaline leachate by using an eco-friendly material that ensures economic efficiency and permeability.

In general, asphalt concrete pavement and concrete pavement with cement as the main material are widely used for road paving. Since water that flows into the road surface during rain does not easily drain into the ground through the pavement layer, not only does it cause various types of obstacles to the movement of vehicles, but the road surface becomes slippery when vehicles move, which can lead to major accidents. In addition, pollutants that are inevitably generated during the production of paving materials cause pollution of the air and water environment.

As a prior art patented technology for resolving problems arising from the use of such packaging materials, the applicant of the present invention is known as Patent No. 10-1118985 entitled ‘Eco-friendly permeable concrete and pavement using the same’.

The above-mentioned conventional permeable concrete of the patented technology forms an inorganic binder by recycling slag fine powder, gypsum, and quicklime instead of asphalt or cement, so that not only can greenhouse gases be reduced by reducing the amount of cement used, but also water pollution caused by strongly acidic leachate from waste gypsum and strongly alkaline leachate from waste lime can be prevented. In addition, by using a stimulant composed of metakaolin and silica, the effects of increasing the adhesive strength, durability, and compressive strength of the concrete can be enhanced.

Specifically, the permeable concrete of the above-mentioned prior art is formed by mixing 78 to 82 wt% of aggregate having a size of up to 13 mm, 14 to 17 wt% of a stimulant, and 4 to 5 wt% of water through room temperature curing, and the composition contained in the stimulant mixes 12 to 13 wt% of an inorganic binder recycled from industrial by-products, 1 to 2 wt% of metakaolin for supplementing binding force, and 1 to 2 wt% of silica for improving moldability, and the inorganic binder is composed of 50 to 70% of slag fine powder, 10 to 15% of sodium aluminum sulfate, 10 to 15% of gypsum, 5 to 10% of quicklime, and 5 to 10% of hardening agent based on the weight of the inorganic binder.

The above-mentioned prior art does not use ordinary cement as aggregate, but uses an inorganic binder and a stimulant composed of metakaolin and silica to secure the bonding and moldability of the concrete, and contains 50 to 70% of slag fine powder, 10 to 15% of sodium aluminum sulfate, and 5 to 10% of quicklime as an inorganic binder, so that the compressive strength, workability, and environmental friendliness are excellent. However, there is a problem that the cost of manufacturing permeable concrete is excessively incurred due to the use of special materials, thereby reducing economic feasibility.

In addition, according to the 'permeable concrete product' certification standard of the environmental label certification standard EL245, the compressive strength standard for permeable concrete pavement used for road pavement that does not receive a large load is stipulated as 14.7 N/ ^mm2 (MPa) or more, and the permeability standard is stipulated as 0.1 mm/sec or more.

The above-mentioned prior art has a permeability coefficient of 0.01 to 0.03 cm/sec, which satisfies the above-mentioned certification criteria. However, when contact with water occurs frequently during the rainy season or at the construction site, the water that has infiltrated through the cracks of the permeable concrete remains for a long period of time, causing moss to grow on the surface of the pavement, or the pavement layer may rot due to the long-term retention of the infiltrating organic matter, generating an unpleasant odor. In particular, in winter, the infiltrated water freezes, causing its volume to expand, cracking or breaking the permeable concrete, damaging the pavement.

Therefore, there is a need to develop an eco-friendly permeable concrete for road paving that is economical while using eco-friendly materials and is composed of a new composition that satisfies the standard strength (21 MPa) for narrow road paving materials of red mix concrete and the compressive strength and permeability coefficient standards of the environmental label certification standards.

The present invention is intended to solve the above-described problems, and more specifically, to provide an eco-friendly permeable concrete for road paving that is economical and has excellent permeability while improving the compressive strength and permeability of permeable concrete for roads by optimizing the amount of eco-friendly materials used while ensuring economical efficiency and permeability.

In order to achieve the above-mentioned object, the present invention provides an eco-friendly permeable concrete for road paving, which is formed by mixing 78 to 82 weight% of aggregate, 14 to 17 weight% of a stimulant, and 4 to 5 weight% of water through room temperature curing, wherein the stimulant is mixed in a ratio of 40 to 45 weight% of ordinary cement for securing the bonding strength of concrete; 5 to 10 weight% of ultra-rapid-setting cement for improving the rapid hardening ability of concrete; 5 to 11 weight% of silica for improving the workability and formability of concrete; 10 to 15 weight% of metakaolin for supplementing the bonding strength of concrete; 5 to 10 weight% of anhydrite for improving the compressive strength of concrete; and 10 to 15 weight% of a solidifying agent for improving the permeability coefficient and void ratio of concrete to secure permeability.

The eco-friendly permeable concrete for road paving of the present invention is formed by mixing ordinary cement, rapid-setting cement, silica, metakaolin, anhydrite, and a solidifying agent at a specific ratio to improve the compressive strength and permeability coefficient of the permeable concrete, thereby improving the durability of a paved road, preventing ground weakening through prevention of water pooling in the paved road and evaporation of infiltrated water, and preventing environmental pollution through reduced cement use, and in particular, producing an effect of improving the permeability coefficient standard value by 3 to 4 times as much as that specified in the eco-label certification standards.

Figure 1 is a drawing illustrating a conceptual diagram of a stimulant composition according to the present invention.
Figure 2 is a drawing that captures the test results of a test specimen 4 formed using only ordinary cement as a stimulant according to the present invention, tested by an authorized testing agency.
Figures 3 to 5 are drawings capturing test results of specimens 14 to 16 formed by including different amounts of a mixture of a stimulant and a hardener according to the present invention, tested by an authorized testing agency.

The eco-friendly permeable concrete for road paving according to the present invention is formed by mixing cement; silica that stimulates improvement of fluidity and formability; metakaolin that improves binding force; anhydrite and a hardener recycled from industrial by-products in a certain ratio.

More specifically, the eco-friendly permeable concrete for road paving of the present invention is formed by mixing 78 to 82 weight% of aggregate, 14 to 17 weight% of a stimulant, and 4 to 5 weight% of water through room temperature curing, wherein the stimulant is formed by mixing in a ratio of 40 to 45 weight% of ordinary cement for securing the bonding strength of concrete, based on the weight of the stimulant; 5 to 10 weight% of ultra-rapid-setting cement for improving the rapid hardening ability of concrete; 5 to 11 weight% of silica for improving the workability and moldability of concrete; 10 to 15 weight% of metakaolin for supplementing the bonding strength of concrete; 5 to 10 weight% of anhydrite for improving the compressive strength of concrete; and 10 to 15 weight% of a solidifying agent for improving the permeability coefficient and void ratio of concrete to secure permeability.

Among the compositions included in the above special concrete, it is preferable to use general rapid-hardening cement, which develops practical strength in just 2 to 3 hours after concrete production, allows the setting time to be controlled with a separate retarder, and ensures stable strength without shrinkage or bleeding, contains chemical components of 14.3 wt% of SiO₂, 11.9 wt% of Al2O3, and 58.7 wt% of Cao, and contains minerals of 46.2 wt% of C3S and 20.8 wt% of C11A7.CaF2, and has physical properties of an initial setting time of approximately 6 minutes and a final setting time of approximately 12 minutes.

In addition, the above silica is a silicic anhydride composed of SiO _2, and is naturally found in quartz, crystal, chalcedony, agate, flint, silica, sapphire, and sapphire as crystals or amorphous forms. It is preferable to use a powder having a purity of 90% or higher and a particle size of 3100 to 3300㎠/g.

The above metakaolin is represented by the chemical formula Al ₂ Si ₂ O ₇ and reacts with Ca(OH) ₂ produced by slag and water glass, and when in contact with water, trace amounts of calcium (CaO) and silicic acid (SiO ₂ ) are dissolved, and insoluble, dense hydrates are produced on the surface of the particles, along with amorphous silica and alumina hydrates. It is preferable to use the metakaolin that, when mixed with cement, causes a pozzolanic reaction in which the Ca(OH) ₂ produced during the hydration reaction reacts with pozzolan, thereby consuming Ca(OH) ₂ and causing a pozzolanic reaction that increases the ratio of CSH in the hydrated cement solidified body.

The above anhydrous gypsum is manufactured using waste gypsum with a pH of 2 to 3 generated during the manufacture of phosphoric acid in a fertilizer plant. It is preferable to use a substance formed by the hydration of anhydrite by surface water and groundwater, which is a sulfate mineral with a chemical structure of CaSO ₄ 2H ₂ O.

The above-mentioned solidifying agent can be applied regardless of organic or inorganic soil, can reduce Cd+6 release that occurs when using cement, hardens over a long period of time, maintains strength, and in particular, it is desirable to use a general surface solidifying agent that can prevent the generation of bad odor and leakage of hazardous substances.

Next, the technical significance and critical significance of the composition and composition ratio of the eco-friendly permeable concrete for road paving according to the present invention are examined through experiments.

Among the above compositions, three specimens were formed by mixing the weight % exceeding or falling short of the normal mixing range and the upper and lower limit threshold values of the normal range for the super-fast-setting cement, silica, metakaolin, anhydrite, and hardening agent included in the stimulant of the permeable concrete, and then specimens formed only with ordinary cement were formed to compare the characteristics of these three specimens and tested according to the national standard test method.

<Experiment 1>

First, Experiment 1, as shown in Table 1 below, is an experiment on the compressive strength of permeable concrete formed by including rapid-setting cement to improve rapid-hardening ability. Three specimens 1 to 3 were formed by mixing the values of rapid-setting cement so that they were within the normal range, exceeding the upper limit of the normal range, and falling below the lower limit of the normal range, and the remaining composition was mixed within the normal range, and a comparative specimen 4 was manufactured only with ordinary cement. Each specimen was formed to be 30 cm in width and length and 28 cm in thickness, and the compressive strength was measured after curing for 28 days.

Specifically, Experiment 1 formed three specimens (a, b, c) of each of Specimens 1 to 4 with different amounts of rapid-setting cement as shown in Table 1-1 below, with a total weight of 6.2 kg (100 wt%). The amount of rapid-setting cement in Specimen 1 was 496 g (8 wt%), which is within the normal range, the amount of rapid-setting cement in Specimen 2 was 682 g (11 wt%), which exceeds the upper limit of the normal range, the amount of rapid-setting cement in Specimen 3 was 248 g (4 wt%), which falls below the lower limit of the normal range, and Specimen 4 was formed with 100% ordinary cement without mixing rapid-setting cement. After 28 days, a test was conducted in accordance with the national standard KS F 2405 (Test method for concrete compressive strength).

As confirmed in Table 1-2 below, the compressive strength of specimen 1 mixed with 8 wt% of ultra-rapid-setting cement, which is within the normal range, was an average of 23.27 MPa for three specimens, the compressive strength of specimen 1 mixed with 11 wt% of ultra-rapid-setting cement, which exceeds the upper limit of the normal range, was an average of 23.6 MPa for three specimens, the compressive strength of specimen 3 mixed with 4 wt% of ultra-rapid-setting cement, which falls below the lower limit of the normal range, was an average of 20.5 MPa for three specimens, and the compressive strength of specimen 4 formed only with ordinary cement was an average of 22.53 MPa for three specimens.

In this way, when the ultra-rapid-hardening cement included in the permeable concrete composition of the present invention is mixed exceeding or falling short of the normal range and the upper and lower limits, the average compressive strength is in the order of 23.6 MPa>23.27 MPa>21.1 MPa, exceeding the upper limit of the normal range, the normal range, and falling short of the lower limit of the normal range, and it was confirmed that when the ultra-rapid-hardening cement is mixed exceeding the normal range and the upper limit of the normal range, the average compressive strength is superior to the average compressive strength of 22.53 MPa of concrete formed only with ordinary cement. Permeable concrete including the ultra-rapid-hardening cement mixing ratio of specimen 1 is made into specific example 1 of the present invention.

<Experiment 2>

Experiment 2 is an experiment on the workability and formability of permeable concrete formed by including silica to improve workability and formability, as shown in Table 2 below. Three specimens 5 to 7 were formed by mixing silica in the normal range, exceeding the upper limit of the normal range, and falling below the lower limit of the normal range, and mixing the remaining composition within the normal range, and observing the workability and formability.

Specifically, Experiment 2 formed specimens 5 to 7 with different silica contents with a total weight of 6.2 kg (100 wt%). In specimen 5, 496 g (8 wt%) of silica, which is within the normal range, was mixed, in specimen 6, 744 g (12 wt%), which exceeds the upper limit of the normal range, and in specimen 3, 248 g (4 wt%), which falls below the lower limit of the normal range, were mixed, and formed in the ratios (wt%) shown in Table 2-1 below, and workability and formability were measured.

As confirmed in Table 2-2 below as a result of the experiment, workability and formability were both excellent and did not collapse even when the formwork was removed when silica was mixed in a ratio of 8 wt% corresponding to the normal range. However, when the specimen was mixed in a ratio of 11 wt% exceeding the upper limit of the normal range and 4 wt% falling below the lower limit of the normal range, the forming work was somewhat difficult and one side broke when the formwork was removed, showing poor results. Permeable concrete including the silica mixing ratio of specimen 5 is designated as a specific example 2 of the present invention.

<Experiment 3>

Experiment 3, as shown in Table 3, is an experiment on the compressive strength of permeable concrete mixed with metakaolin to supplement the bonding strength of concrete. Three specimens 8 to 10 were formed, each measuring 30 cm in width and length and 28 cm in thickness, by mixing metakaolin in amounts below the normal range, the upper limit of the normal range, and below the lower limit of the normal range, and mixing the remaining composition within the normal range. The bonding strength was measured after 28 days to confirm the bonding strength. The comparative specimen 4, which is usually manufactured only with cement, is applied as is to the results of Experiment 1.

Specifically, Experiment 3 formed three specimens (a, b, c) each of Specimens 8 to 10 with a total weight of 6.2 kg (100 wt%) containing silica. Specimen 8 was mixed with 806 g (13 wt%) of metakaolin, which was within the normal range, Specimen 9 was mixed with 1054 g (17 wt%) of metakaolin, which exceeded the upper limit of the normal range, and Specimen 3 was mixed with 558 g (9 wt%) of metakaolin, which was below the lower limit of the normal range. The specimens were formed at a ratio as shown in Table 3-1 below, and a test was conducted after 28 days in accordance with the national standard KS F 2405 (concrete compressive strength test method).

As confirmed in Table 3-2 below, the compressive strength of specimen 8 mixed with 13 wt% metakaolin, which is within the normal range, was an average of 23.4 MPa for three specimens, the compressive strength of specimen 9 mixed with 17 wt% metakaolin, which exceeds the upper limit of the normal range, was an average of 23.5 MPa for three specimens, and the compressive strength of specimen 3 mixed with 9 wt% metakaolin, which falls below the lower limit of the normal range, was an average of 20.26 MPa for three specimens. As seen in Experiment 1 above, the compressive strength of specimen 4 formed only with ordinary cement was an average of 22.53 MPa for three specimens.

In this way, the average compressive strength of the metakaolin included in the permeable concrete composition of the present invention is in the order of 23.6 MPa > 23.26 MPa > 20.5 MPa, which is within the normal range of the mixed metakaolin, exceeding the upper limit of the normal range, and falling below the lower limit of the normal range, and it was confirmed that the compressive strength is further improved when the metakaolin content is high. The permeable concrete including the metakaolin mixing ratio of specimen 8 is a specific example 3 of the present invention.

<Experiment 4>

Experiment 4, as shown in Table 4 below, is an experiment on the compressive strength of permeable concrete mixed with anhydrite to improve the compressive strength of concrete. Three specimens 11 to 13 were formed, each measuring 30 cm in width and length and 28 cm in thickness, by mixing anhydrite in amounts below the normal range, the upper limit of the normal range, and below the lower limit of the normal range, and mixing the remaining composition within the normal range. The compressive strength was measured after hardening for a certain period of time. The comparative specimen 4, which is usually manufactured only with cement, is applied as is to the results of Experiment 1.

Specifically, Experiment 4 formed three specimens (a, b, c) each of Specimens 11 to 13 with different anhydrite contents, with a total weight of 6.2 kg (100 wt%). In Specimen 11, 620 g (10 wt%) of anhydrite was mixed, which is within the normal range, in Specimen 9, 682 g (11 wt%), which exceeds the upper limit of the normal range, and in Specimen 3, 248 g (4 wt%), which falls below the lower limit of the normal range, were mixed. The specimens were formed in the ratios shown in Table 4-1 below, and a test was conducted after 28 days in accordance with the national standard KS F 2405 (concrete compressive strength test method).

As confirmed in Table 4-2 below, the compressive strength of specimen 11 mixed with 10 wt% anhydrite, which is within the normal range, was an average of 23.4 MPa for three specimens, the compressive strength of specimen 12 mixed with 12 wt%, which exceeds the normal range, was an average of 23.9 MPa for three specimens, and the compressive strength of specimen 3 mixed with 4 wt% anhydrite, which is below the normal range, was an average of 20.26 MPa for three specimens. As seen in Experiment 1 above, the compressive strength of specimen 4 formed only with ordinary cement was an average of 22.53 MPa for three specimens.

In this way, the average compressive strength of anhydrite included in the permeable concrete composition of the present invention is 23.5 MPa>23.4 MPa>20.26 MPa in the order of exceeding the upper limit of the normal range of anhydrite, falling below the normal range, and falling below the lower limit of the normal range, and it was confirmed that when anhydrite is mixed in excess of the normal range and the upper limit of the normal range, it is higher than the compressive strength of 22.53 MPa of concrete using only ordinary cement. Permeable concrete including the anhydrite mixing ratio of specimen 11 is made into a specific example 4 of the present invention.

<Experiment 5>

Experiment 5, as shown in Table 5 below, is an experiment related to the case of mixing a solidifying agent to improve the permeability coefficient and void ratio of concrete. Three specimens 14 to 16 were formed with a width and length of 30 cm and a thickness of 28 cm, respectively, by mixing the solidifying agent so that it was within the normal range, the upper limit of the normal range, and the lower limit of the normal range, and the remaining composition was mixed within the normal range. The compressive strength, permeability coefficient, and void ratio were measured after 28 days. The compressive strength of comparative specimen 4, which is usually manufactured only with cement, is applied as is to the result of Experiment 1.

Specifically, Experiment 5 formed three specimens (a, b, c) each of Specimens 14 to 16 with different amounts of solidifier, with a total weight of 6.2 kg (100 wt%). Specimen 14 contained 930 g (15 wt%) of solidifier, which is within the normal range, Specimen 15 contained 1054 g (17 wt%), which exceeds the upper limit of the normal range, and Specimen 16 contained 558 g (9 wt%), which falls below the lower limit of the normal range. The specimens were formed at a ratio as shown in Table 5-1 below, and a test was conducted after 28 days in accordance with the national standards KS F 2405 (Test method for concrete compressive strength) and KS F 2322 (Test method for soil permeability).

As confirmed in Table 5-2 below, the compressive strength of specimen 14, which was mixed with 10 wt% of the solidifying agent, which is within the normal range, was an average of 23.6 MPa for three specimens, the compressive strength of specimen 15, which was mixed with 11 wt% of the solidifying agent, which exceeded the upper limit of the normal range, was an average of 23.2 MPa for three specimens, and the compressive strength of specimen 16, which was mixed with 9 wt% of the solidifying agent, which fell below the lower limit of the normal range, was an average of 23.4 MPa for three specimens. As seen in Experiment 1 above, the compressive strength of specimen 4, which was formed only with ordinary cement, was an average of 22.53 MPa for three specimens.

Also, as confirmed in Table 5-2, the average permeability coefficient and porosity were 0.409 cm/sec and 21.1% in Specimen 14, 0.583 cm/sec and 21.1% in Specimen 15, 0.377 cm/sec and 20.3% in Specimen 16, and 0.803 cm/sec and 18.3% in Specimen 4.

In this way, it was confirmed that the hardening agent included in the permeable concrete composition of the present invention was 23 MPa or more in all cases where it exceeded the normal range and the upper limit of the normal range and fell below the lower limit of the normal range, which was superior to the average compressive strength of 22.53 MPa of specimen 4 formed only with ordinary cement.

And the average permeability coefficient and void ratio were 0.409 cm/sec and 21.1% for Specimen 14, 0.583 cm/sec and 21.1% for Specimen 15, and 0.377 cm/sec and 20.3% for Specimen 16, and the permeability coefficient and void ratio of Specimen 4 formed only with ordinary cement were 0.83 cm/sec and 18.3%, confirming that the permeable concrete of the present invention including a hardener has a lower permeability coefficient but a larger void ratio than concrete formed only with ordinary cement.

In particular, it was confirmed that specimens 14 to 16, which tested the coefficient of permeability, showed a coefficient of permeability 3 to 5 times higher than the standard of 0.1 mm/sec for permeable concrete pavement used for road pavement that does not receive a large load as specified in the certification standard of ‘permeable concrete product’ of the environmental label certification standard EL245 while using eco-friendly materials. Permeable concrete including the mixing ratio of the solidifying agent of specimen 14 is made into a specific example 5 of the present invention.

In order to prove the superiority of the eco-friendly permeable concrete for road paving in the present invention through tests by an authorized institution, test results from a domestic authorized testing institution are attached as Figs. 2 to 5 for specimen 4 of Experiment 1 formed only with ordinary cement and specimens 14, 15, and 16 of Experiment 5, which were tested by changing the mixing ratio of the solidifying agent to increase permeability and porosity. A copy of the test results is attached to the patent application.

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Claims (5)

In permeable concrete formed by mixing 78 to 82 weight percent of aggregate, 14 to 17 weight percent of stimulant, and 4 to 5 weight percent of water through room temperature curing,
The above stimulant is characterized by being formed by mixing in a ratio of 40 to 45 weight% of ordinary cement for securing the bonding strength of concrete based on the weight% of the stimulant; 5 to 10 weight% of ultra-rapid-hardening cement for improving the rapid hardening ability of concrete; 5 to 11 weight% of silica for improving the workability and formability of concrete; 10 to 15 weight% of metakaolin for supplementing the bonding strength of concrete; 5 to 10 weight% of anhydrite for improving the compressive strength of concrete; and 10 to 15 weight% of a solidifying agent for improving the permeability coefficient and void ratio of concrete to secure permeability. delete delete delete delete