JPH02157302A - Permeable cement concrete board - Google Patents

Abstract

PURPOSE:To improve permeability and water retentivity and to give a natural appearance by shot blast processing the surface of a curing cement concrete mixture consisting of cement, water, sand and the like of a specific ratio. CONSTITUTION:Portland cement of 300 to 400kg/m<3> of a cement concrete mixture binder of 0.008 to 0.04 parts by weight to 1 parts by weight of the cement, water of 0.3 to 0.45 parts by weight, sand of residual part having the weight ratio of 5:95 to 20:80, a skeleton material consisting of No. 7 crushed stone or natural and/or artificial gravel are kneaded, filled to a mold and cured. Then, the surface of the cured product is washed by the use of a shot blast machine to remove cement mortar adhering on the surface of the skeleton material, manufacture permeable cement concrete board, produce a natural color and apply stability.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a water-permeable cement concrete slab.

[Conventional technology]

In recent years, as the trend of urbanization progresses, its negative effects have become noticeable in many areas.

In particular, asphalt pavement, concrete pavement, and various buildings obstruct the infiltration and water retention of rainwater that previously permeated into the soil, which is becoming more serious as urbanization progresses. . In other words, the decrease in the land surface through which rainwater can permeate results in a rapid decrease in groundwater, which causes the ground to sink, slows down the growth of trees, changes the ecology of soil organisms, and furthermore causes the above-mentioned problems. Due to the decrease in permeable land surface and the difficulty in retaining water near the ground surface, when rainfall occurs intensively in a short period of time, rivers can grow even though the total amount is not that large. Flooding and disruption of transportation networks are causing major social problems, and solutions to these problems are urgently needed.

Apart from the above-mentioned point of view, especially recently, with regard to sidewalks and plazas, there has been an increase in the use of color schemes with a focus on ``moisture J''. The methods used include mixing various pigments into asphalt or cement concrete in advance and kneading them, or spraying the pigments onto the pavement surface using a spray gun.

[Problem that the invention seeks to solve]

From the above-mentioned viewpoints of water permeability and water retention, there is a strong desire for a pavement that is excellent in these properties, and water permeable asphalt exists to meet these demands. However, water permeable asphalt is not always satisfactory as it still does not have sufficient water permeability and water retention, the asphalt melts due to sunlight and becomes clogged, further reducing water permeability, and the asphalt deteriorates significantly over time. For this reason, water permeable concrete using cement concrete is attracting attention, and it is hoped that practical concrete with excellent water permeability and water retention will be provided.

Also, from the perspective of coloring pavement, the method of coloring pavement as described above is different from natural colors, and visually
It gives an artificial feel, and as a result, it is difficult to say that it has succeeded in imparting "moisture".

[Means for solving problems]

Therefore, the present invention was devised for the purpose of creating a cement concrete slab with excellent water permeability and water retention properties and a natural color.

i.e. 300-400 kg of Portland cement;
0.008 to 0.04 parts by weight of binder and 0.3 to 0.45 parts by weight of water per 1 part by weight of cement, and 5:
Sand and No. 7 crushed stone in a weight ratio of 95 to 20:80 or 5 to
By devising a cement concrete plate in which 10 m5+ of aggregate made of natural or artificial gravel is distributed almost uniformly and has a volume of 1 rrr, and the surface of the cement concrete is shot-blasted, water permeability and This creates a concrete slab with excellent water retention and natural coloring.

〔Effect of the invention〕

In the present invention, the aggregate exposed on the surface of pavements such as sidewalks and plazas is shot blasted to reveal its own natural color, which conventionally gave a visually artificial appearance. Unlike colored pavement, it has a "moisture" effect.
Give to those who see it.

Furthermore, by having the above-mentioned structure, the present invention has sufficient strength for practical use, exhibits water retention properties similar to those exhibited by ordinary soil during rainfall, and is capable of retaining water much better than conventional asphalt pavement or cement concrete. It achieves rapid water permeability that is incomparable to pavement. The hydraulic conductivity is on the order of 10-' to 10-' cm/sec, typically on the order of 10-' to 10-3 cm/sec.

Compared to conventional water-permeable pavements, the present invention is significantly different from conventional water-permeable pavements in that it is less susceptible to clogging over time and does not melt under high temperatures.

Furthermore, the present invention has a very high porosity considering its strength, reaching 20 to 30%. As a result, even if fine earth and sand accumulates on the surface of the concrete slab, it will flow through the gaps when it rains, making it relatively unlikely to cause clogging.

While the present invention exhibits large porosity and water permeability as described above, it also has sufficient strength for practical use. Its compressive strength is 100-200 kg/C111 (4 week strength, 2
0°C constant temperature water curing), bending strength is 20 to 30 kg/c
ffl (4 week strength, 20°C constant temperature water curing) is obtained.

[Example] 300 to 40 per bottle of cement concrete mixture
0 kg of Portland cement, 0.008 to 0.04 parts by weight (solid content) of binder, 0.3 to 0.45 parts by weight of water, and the balance 5 to 1 part by weight of cement.
:95 to 20 :80 weight ratio of sand and aggregate consisting of No. 7 crushed stone or natural or artificial gravel of 5 to 10 mm are mixed, the resulting mixture is poured or cast, and then hardened. The surface of this hardened material is washed out using a known machine (commonly known as a shot blasting machine) to remove the cement mortar part attached to the aggregate surface on the surface of the concrete slab. , to produce the water-permeable cement concrete of the present invention.

In the aggregate in the present invention, sandia crushed stone or 5 to 10 m
The weight ratio of natural or artificial gravel is 5:95-20:
It needs to be 80. A ratio of 5:95 is suitable for pavement for sidewalks, and a ratio of 10:90 or more is suitable for pavement for light traffic. A part of this aggregate, preferably 10 to 30% by weight, can be replaced by No. 6 crushed stone or 10 to 20M natural or artificial gravel. In this case, it is preferable in that the strength increases to some extent, but it has the disadvantage that the appearance is not good because large crushed stones and gravel are mixed in the No. 7 crushed stone or the natural or artificial gravel of No. 5 to IOM.

The amount of portland cement is 300 to 400 per rrl of the total cement concrete mixture including water.
kg, preferably 320-370 kg.

0.008 to 0.040 M per 1 part by weight of cement
One part, preferably from 0.015 to 0.03 parts by weight, of a binder is added, which can be any binder commonly known for addition to cement mortars.

Natural or synthetic rubbers such as SBR, NBR, acrylic resins, epoxy resins, etc. can be used, and these binders are usually added as an emulsion. The amount of binder mentioned above indicates the amount of resin in the emulsion as a solid content. For example, commercially available SB
If the R-based latex binder (JSRI-Max-Par, manufactured by Japan Synthetic Rubber Co., Ltd.: solid content 0545%) is used within the above range, an improvement in bending strength of about 10 to 60% will be achieved, but if it exceeds this range, This is not preferable because the water permeability is significantly reduced.

The amount of water is 0.30 to 0.45 per 1 part by weight of cement.
Parts by weight, preferably 0.35 to 0.40 parts by weight.

If the amount of water is more than the upper limit, the water permeability will deteriorate, while if the amount is less than the lower limit, sufficient mixing will not be possible.

The shot blasting member used for polishing is, for example, ball-shaped iron (with a diameter of about 2 mm or less) or sand (with a diameter of 0 mm or less).
, 6 mm or less of silica sand) is used to collide with the cement concrete surface using a grinder to remove the cement mortar adhering to the aggregate.

Claims (1)

[Claims] 300 to 400 kg of Portland cement, 0.008 to 0.04 parts by weight of binder and 0.3 to 0.45 parts by weight of water per 1 part by weight of cement, and 5:95 to 20 parts by weight. :80 weight ratio of sand and No. 7 crushed stone or 5-10mm
A water-permeable cement concrete slab made of a hardened cement concrete mixture having a volume of 1 m^3 in which aggregate consisting of natural or artificial gravel is distributed almost uniformly, and the surface of the hardened cement concrete mixture is shot-blasted.