JP2988196B2 - Pavement block and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sidewalk, a park, a parking lot,
The present invention relates to a cement-based pavement block used for pavement of a roadway and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Pavement blocks (interlocking blocks) have been widely used for pavements such as sidewalks and parks because of the increasing demand for cityscapes. Paving blocks are roughly classified into three types: cement-based, pottery-based, and resin-based. Among them, cement-based pavement blocks are widely used because of their superiority in cost and flexibility in shape as compared with the other two types. A conventional cement-based pavement block uses cement as a binder, kneads the cement binder, aggregates such as crushed stones, a pigment, and water, and then forms the same into a predetermined shape. Cured in a sheet of vinyl or the like (for example,
No. 561).

[0003]

However, although cement-based pavement blocks are widely used because of their flexibility and low cost, they have low surface wear resistance and are easily worn away. there were.

Therefore, as a curing technique for cement or the like, a high-strength cured product (JP-A-4-349161) and a method for increasing the chemical durability of the cement (JP-A-59-8838).
No. 7), a method for curing converter slag (Japanese Patent Laid-Open No. 56-38)
No. 549) has been proposed, but even in such a case, there is a problem of color change due to whitening of the cement and fading due to abrasion of the surface. This efflorescence phenomenon is caused by the hydration reaction of cement, resulting in calcium oxide "CaO"
When a hydrate composed of silicon oxide “SiO ₂ ” and water “H ₂ O” (hereinafter referred to as CSH) is generated, CaO contained in the cement is excessive with respect to SiO ₂ . This occurs because excess CaO becomes calcium hydroxide “Ca (OH) ₂ ” as the hydration reaction proceeds and precipitates on the block surface. For this reason, the block becomes white. It has long been known that this can be prevented by preventing excess Ca (OH) ₂ from depositing on the block surface. However, at present, no effective means for preventing efflorescence has been developed except for resin coating, and resin coating has a high product cost, and thus has not been widely used.

In view of the above, it is an object of the present invention to provide a cement-based pavement block having a high surface hardness, excellent abrasion resistance, and excellent resistance to color and color fading, and a method for producing the same.

[0006]

According to the present invention, there is provided a pavement block comprising a binder obtained by mixing one or more kinds of materials such as calcium cement, slaked lime, granulated blast furnace slag, a coarse aggregate and water. And a second layer formed by kneading a binder obtained by mixing one or more materials such as calcium cement, slaked lime, granulated blast furnace slag, fine aggregate, pigment and water. And molded into a molded body having a predetermined shape, and the molded body is formed within 72 hours in which no whitening occurs.
After performing normal curing for a period during which the shape can be maintained, carbonation curing by exposing to a carbon dioxide gas atmosphere is started to form a carbonated hard layer on the surface side of the molded body.

Further, the method for producing a pavement block according to the present invention comprises kneading a binder obtained by mixing one or more materials such as calcium cement, slaked lime, granulated blast furnace slag, coarse aggregate and water. Casting a predetermined amount into a mold to form a first layer; and a binder, a fine aggregate, a pigment and water obtained by mixing one or more kinds of materials such as a calcium cement material, slaked lime, and granulated blast furnace slag. Kneading and pouring a predetermined amount onto the first layer in the mold to form a second layer, and within 72 hours after the compaction by vibration , no whitening occurs
When the two-layer structure in the mold can maintain its shape
Between the step of performing normal curing and the above taken out of the formwork
Starting carbonation curing by exposing the molded body after curing to a carbon dioxide gas atmosphere within 72 hours during which the efflorescence does not occur , and forming a carbonized hard layer on the surface side of the molded body. It is characterized by.

[0008]

In the present invention, a calcium cement material,
Calcium cement, slaked lime, granulated blast furnace slag, etc. on a first layer obtained by kneading a binder mixed with one or more of materials such as slaked lime and granulated blast furnace slag, coarse aggregate and water kneading one or more mixed binder and fine aggregate and pigment and water of the material the second layer was laminated comprising, formed into molded body having a predetermined shape, it does not occur with efflorescence 72
Normally within the time and the time during which the molded body can hold
Curing and exposing to carbon dioxide atmosphere after curing
Start, the calcium oxide “CaO” contained in the binder from the surface side of the molded body is changed to calcium carbonate “CaC”.
O ₃ is converted to a binder to form a hard layer.
Most of the binder after the carbonation reaction becomes CaCO ₃ and a silicon oxide gel “SiO ₂ gel”, so that the efflorescence phenomenon hardly occurs and the color and discoloration resistance are improved.

In addition, since CaO contained in the binder is converted into CaCO ₃ from the surface side of the compact to form a hard layer, calcium hydroxide “Ca (OH) ₂ ” precipitated by excess CaO inside the compact is formed. The amount becomes a very small amount when viewed as the whole molded body, and further precipitated Ca (OH) ₂ is
The escape to the outside is prevented by the hard layer made of CaCO ₃ on the surface side of the molded body. The Ca (OH) _{2, which} is prevented from escaping to the outside, forms a hard layer around the aggregate inside the molded body. This Ca (OH) ₂ is a harder mineral than C—SH and contributes to increasing the hardness inside the compact.

[0010] Further, since the pigment is mixed with the binder and fixed, if the binder is converted into a hard binder, the adhesion is improved. Further, since the hard layer formed of CaCO ₃ is harder than C—S—H and has excellent wear resistance, the resistance to abrasion of the surface of the carbonated molded body is improved.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a perspective view showing the structure of a pavement block according to one embodiment of the present invention, which is crushed in the longitudinal direction at a longitudinal center portion thereof, and FIG. 2 is an enlarged view of a carbonated portion of a molded body constituting the block. FIGS. 3 to 8 are explanatory views schematically showing the steps of the manufacturing method. In FIG. 1, reference numeral 1 denotes a carbonated and cured body constituting a pavement block according to the present embodiment, which is formed into a prism having a length of 8 cm, a width of 11 cm, and a length of 22 cm. The molded body 1 is composed of a first layer 3 in which coarse aggregate 2a such as crushed stone, river gravel, blast furnace slag, concrete waste, etc., having a size of 6 to 7 is mixed into a calcium cement material such as ordinary cement or white cement. And a second layer 4 integrated with the first layer 3 by mixing fine aggregates 2b such as river sand having a particle size of about 0.8 mm and pigments such as redwood into the same calcium-based cement material. A hard layer 5 (shaded portion in the figure) having a thickness of several cm is formed on the surface side by carbonation curing.

As shown in FIG. 2, the hard layer 5 is formed by, for example, applying cement 6 around the aggregate 2 to a thickness of about 0.3 to 0.5 like an egg shell.
A mm-thick CaCO ₃ coating 7 covers and is formed by bonding together.

This will be described in detail according to the manufacturing procedure. First, a calcium-based cement material 8 such as ordinary cement or white cement, a coarse aggregate 2a, and water are kneaded and poured into a mold 9 in a predetermined amount to form a first layer. 3 (FIGS. 3 and 4).
Next, the same calcium cement material 8 and fine aggregate 2b
The mixture, the pigment and water are kneaded, and a predetermined amount is poured onto the first layer 3 in the mold 9 to form the second layer 4 (FIGS. 5 and 6). Next, after compaction by vibration, normal curing is performed within 72 hours and for a time during which the molded body in the mold 9 can maintain its shape. When the shaped body 1a that is undergoing curing can maintain its shape by the hydration reaction, it is taken out of the mold 9 and transferred into the container 10 (FIG. 7).
In an atmosphere of carbon dioxide gas 11 having a concentration of 10 to 100 v%, 30
Expose for minutes to 72 hours (this is called carbonation curing). If the carbonized curing results in a molded article 1 in which a hard layer 5 having a thickness of several cm is formed on the surface side of the molded article (FIG. 8), the container 10
The molded body 1 is taken out from the inside. Number c on the surface side of this molded body
The carbonation curing time (30 minutes to 72 hours) required to form the hard layer 5 having a thickness of m is obtained in advance by experiment for each type of molded product, and the carbonation curing time corresponding to the type of molded product is determined. When the curing time has elapsed, it is considered that the hard layer 5 has been formed. Further, the carbonation curing is not necessarily performed in the container 10; in other words, as long as an atmosphere having a predetermined carbon dioxide gas concentration and temperature can be maintained for a predetermined time, it can be indoors, in a sheet of vinyl or the like, or outdoors. It is possible.

In the pavement block of the present embodiment manufactured by the above-described manufacturing method, the uncured compact 1
The reason for causing a to undergo a carbonation reaction within 72 hours is that it is necessary to convert CaO contained in the cement into CaCO ₃ by carbonation before the efflorescence phenomenon of the cement appears. The efflorescence phenomenon of cement appears 3 to 4 days after mixing cement and water. The effect of carbonation on the prevention of efflorescence is effective before efflorescence occurs. However, when efflorescence is produced and then carbonized, Ca (OH) _{2 on the} surface is carbonated, so that efflorescence becomes more intense. Would. Therefore, the time until carbonation curing was set to 72 hours or less. The reason why the time from molding to carbonation curing is increased is that carbonation curing may be performed immediately after molding, but the carbonation reaction rate is greatly affected by the amount of free water contained, and the maximum value is free. The amount of water, expressed as a weight percentage divided by the amount of cement, is 15
wt%. This water content is very small as compared with a general molding water content (25 to 50 wt%) of the pavement block. Therefore, the rate of the carbonation reaction is low, and as a result, the production efficiency is extremely deteriorated. However, it is difficult and difficult to achieve a molding water content of the block of 15 wt%. Therefore, as a result of considering whether there is a method to improve the carbonation reaction efficiency without changing the conventional production process, the hydration reaction of the cement fixes the forming water and reduces the free water, thereby increasing the carbonation reaction rate. I discovered a previously unknown phenomenon of getting faster. Based on this discovery,
The hydration time up to carbonation curing was set freely within 72 hours, during which no efflorescence occurred, depending on the amount of molding water.

Since the concentration of carbon dioxide greatly affects the reaction rate, a higher concentration is preferable. However, considering the cost, high-concentration gas is expensive, and as a result of examination together with the curing time so that general exhaust gas can be used, as shown in Table 1 below, even with 5 v% concentration carbon dioxide gas, Although it is recognized that there is a sufficient effect on suppression of efflorescence and hardening of the surface, it is more preferable that the concentration of carbon dioxide is 10 v% or more. Therefore, the carbon dioxide concentration is 10 to 100 v%
And In addition, v% is a volume percentage.

[0016]

[Table 1]

In Table 1, ΔL ^* indicates a difference in lightness of the test piece with reference to the lightness of the test piece when the carbon dioxide concentration is 0. Table 1 shows the metric saturation (c) with respect to the carbon dioxide concentration.
^* = (A ^{* 2} + b ^{* 2} ) ^1/2 ), an example of measurement of lightness L ^* , and abrasion loss (head drop method). The condition in this case is as follows: the pigment mixed into the second layer is red using Bengala, and the mixing ratio (w / c) of water and cement is 30 wt.
%, The curing time before carbonation was 24 hours (h), and the carbonation curing time was 24 hours (h). Here, the curing time before carbonation refers to a normal curing time after the molded body 1a is taken out of the mold 9. Metric saturation (c ^* = (a ^{* 2} +
The measurement of b ^{* 2} ) ^1/2 ), the lightness L ^* , and the amount of wear (drop method) were performed according to the following measurement methods.

In order to evaluate the test piece's resistance to efflorescence, color, and colorfastness, first, the spectral solid angle reflectance R (λ) of the test piece is measured according to the method specified in JISZ8722 “Method for measuring object color”. did. That is, the specimen is evenly illuminated from all directions, and the spectrophotometer receives reflected light in the direction at an angle of 8 ° with the normal to the test surface, and the spectral solid angle reflectance R (λ ) Was measured. In this case, the light source is JI
A D ₆₅ light source specified by SZ8720 was used. next,
From the measured spectral solid angle reflectance R (λ), the tristimulus values X, Y, Z and x, y, z of the object color due to the reflection of the test object and x, y, z in the XYZ color system are represented by JISZ8701 “Color display method by color system”. The numerical value of the object color was calculated by the method of the following formula (1) using the method defined in "1."

[0019]

(Equation 1) Further, the tristimulus value Y in the XYZ color system is a value representing the luminous solid angle reflectance in percentage.

Further, based on the tristimulus values X, Y, and Z of the object color due to the reflection of the test object, the object color of the test object is determined according to JISZ87.
The display was performed in the L ^* a ^* b ^* color system specified in 29 "Display Method of Object Color". According to JISZ8729, L ^* ,
a ^* and b ^* are calculated by the following equations (2) and (3).

[0021]

L ^* = 116 (Y / Yn) ^1/3 −16 Y / Yn> 0.008856 where Y: value of tristimulus value in XYZ system Yn: value of Y by standard light of perfect diffuse reflection surface

[0022]

A ^* = 500 [(X / Xn) ^1/3 − (Y / Yn) ^1/3 ] X / Xn> 0.008856 b ^* = 200 [(Y / Yn) ^1/3 − (Z / Zn ) ^1/3 ] Y / Yn> 0.008856 Z / Zn> 0.008856 where X, Y, Z: tristimulus values in XYZ system Xn, Yn, Zn: tristimulus values in XYZ system of perfect diffuse reflection surface

The color name and L ^* of the object color when actually observed
The relationship between the numerical values displayed in the a ^* b ^* color system is described in Color Technology Handbook, (October 1, 1990), General Technology Center Co., Ltd., Yukio Murata, p. According to 118-119,
They are related as follows. That is, the lightness index L
^The larger the value ^{*, the} whiter the object color becomes. On the contrary, the smaller the lightness index L ^{*, the} more the object color becomes black. This can be understood from the relationship between the brightness V of the object color specified in JISZ8102 and the object color when actually observed. That is, according to JISZ8102, the greater the value V of the object color, the whiter the object color becomes, and conversely, the smaller the value V of the object color, the greater the degree of blackness of the object color. On the other hand, according to JISZ8721, the lightness V indicates a larger value as the luminous solid angle reflectance Y increases. Further, from the relationship between the XYZ color system and the L ^* a ^* b ^* color system, the larger the value of L ^* , the larger the luminous solid angle reflectance Y and the value of the lightness V. From the above, the bleaching resistance of the pavement block was evaluated by L ^* .

The color and the colorfastness of the pavement block are determined by the metric saturation (a ^{* 2} + b ^{* 2} ) ^1/2.
Was evaluated. That is, according to the color technology handbook, the metric saturation (a ^{* 2} + b ^{* 2} ) ^1/2 is
It represents the properties of the color corresponding to the content of the pure color component. Therefore, as the metric saturation (a ^{* 2} + b ^{* 2} ) ^1/2 increases, the content of the pure color component increases, and conversely, as the metric saturation (a ^{* 2} + b ^{* 2} ) ^{1/2 approaches} zero, Object color close to achromatic. In other words, the larger the metric saturation (a ^{* 2} + b ^{* 2} ) ^{1/2 of} the test sample indicates, the more excellent the color and the color fading resistance, and the higher the metric saturation (a
^{* 2} + b ^{* 2} ) It is considered that the smaller the value of ^1/2 is, the more severe the color and discoloration are.

The abrasion resistance was evaluated as follows. That is, as a test device, JISA1452
The device specified in was used. The test surface of the test specimen was placed at 45 ° from the horizontal, and 10,000 g of the abrasive was dropped from above the center of the test specimen by 650 mm, and the weight loss of the test specimen was measured. During the test, the test was performed while rotating the specimen around the center of the test surface. The size of the test body was 8 cm in length, 11 cm in width, and 22 cm in length. As the abrasive, a silicon carbide abrasive 2C defined in JISR6111 was used. The size of the abrasive is 36,
The test was performed by controlling the amount of drop at 400 ± 20 g per minute.

Incidentally, the temperature is not strictly specified in the production of the paving block of the present invention, but it is not preferable that the temperature is lower than 10 ° C., because the reaction is easily slowed down. On the other hand, if the temperature is higher than the boiling point of water, the amount of water required for the carbonation reaction becomes insufficient due to evaporation, which is not preferable. The humidity is not particularly limited, but may be set according to the free water content and the curing temperature of the block.

Tables 2 and 3 below show the measured values of Examples A to I in which the specifications of the paving block of the present invention were different from those of the conventional example.

[0028]

[Table 2]

[0029]

[Table 3]

ΔE ^* in Tables 2 and 3 is JISZ87
The L ^* a ^* b ^* color system defined in 30 shows the color difference between the conventional example and each of the blocks A to I. In addition, v% indicates volume percentage, wt% indicates weight percentage, and h indicates time.
Tables 2 and 3 use a block made of a common cement material in which the second layer is colored with a red pigment such as red iron oxide. In the block examples A to I of the present invention, carbonation curing was performed under each condition in the table. It was done. As is clear from Tables 2 and 3, it can be seen that carbonation within 72 hours after molding is effective in suppressing the whitening of the block and in improving the color and colorfastness. Further, it can be seen that the abrasion resistance (abrasion resistance) of the block was improved by carbonation.

[0031]

As described above, according to the present invention, a binder obtained by mixing one or more materials such as calcium cement, slaked lime, granulated blast furnace slag, coarse aggregate and water are kneaded. One or two materials such as calcium cement material, slaked lime, granulated blast furnace slag, etc.
A second layer formed by kneading a binder, fine aggregate, pigment and water mixed with more than one kind is laminated and molded into a molded article having a predetermined shape ,
Within 72 hours when no efflorescence occurs and the molded body has a shape
After performing normal curing for a period of time that can be maintained, carbonation curing is started by exposing in a carbon dioxide gas atmosphere, and a carbonized hard layer is formed on the surface of the molded body , so the surface hardness is high and wear resistance is high. It was possible to obtain a pavement block excellent in properties and color / fading resistance . Also, the carbonation reaction rate is fast.
To improve production efficiency and reduce CO2 consumption
As a result, costs could be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a pavement block according to an embodiment of the present invention, which is crushed in a longitudinal direction at a longitudinal center portion thereof.

FIG. 2 is an explanatory view schematically showing, in an enlarged manner, a carbonated portion of a molded body constituting the block of FIG. 1;

FIG. 3 is an explanatory view illustrating a first step of a method for manufacturing a pavement block according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram for describing a first step of a method for manufacturing a pavement block according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining a second step of the method for manufacturing a pavement block according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining a second step of the method for manufacturing a pavement block according to one embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining a third step of the method for manufacturing a pavement block according to one embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining a fourth step of the method for manufacturing a pavement block according to one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1, 1a molded body 2a coarse aggregate 2b fine aggregate 3 first layer 4 second layer 5 hard layer 8 binder 9 formwork 11 carbon dioxide

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 13/00-40/02

Claims (2)

(57) [Claims] 1. A first layer obtained by kneading a binder obtained by mixing one or more kinds of materials such as calcium cement material, slaked lime, granulated blast furnace slag, coarse aggregate and water, and a calcium cement material , Slaked lime, blast furnace granulated slag, etc., a binder obtained by mixing one or two or more kinds, a fine aggregate, a second layer formed by kneading pigment and water, and forming a molded body having a predetermined shape , Within 72 hours when white flower does not occur and the above
After performing normal curing for a period during which the molded body can maintain its shape, start carbonation curing by exposing it to a carbon dioxide gas atmosphere, and form a carbonized hard layer on the surface of the molded body for pavement. block. 2. Kneading a binder obtained by mixing one or more kinds of materials such as calcium cement material, slaked lime, granulated blast furnace slag, coarse aggregate and water, and pouring a predetermined amount into a mold to form a first layer Forming a first layer in a mold by kneading a binder, a fine aggregate, a pigment and water obtained by mixing one or two or more materials such as calcium cement material, slaked lime, granulated blast furnace slag, etc. a step of forming a predetermined amount pouring a second layer on top, after compacted vibro, or within 72 hours does not occur with efflorescence
That the two-layered molded product in the mold can maintain its shape
A step of performing normal curing , and removing the molded body after the normal curing taken out of the mold from the white
Exposing in a carbon dioxide atmosphere within 72 hours does not occur Hua
Starting carbonation curing to form a carbonated hard layer on the surface of the molded body.