JP2002029814A - Concrete and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the corrosion of a reinforcing bar due to a chloride incorporated from a material such as sea sand at the time of concrete manufacture when the sea sand is used as a fine aggregate for concrete. SOLUTION: The concrete is manufactured from crushed stone, stone powder, lime and cement by using the stone powder and the lime in place of the sea sand and the manufacturing method is provided. In the compounding 300-500 kg/m3 cement, 300-400 kg/m3 stone powder, 1500 kg/m3 crushed stone per 1 m3 concrete and 5-20% lime to the weight of the cement are used. The particle diameter of the crushed stone is smaller than that of the conventional crushed stone and is controlled to 2-7 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to concrete manufactured without using sea sand in order to prevent deterioration of concrete structures due to salt damage, and to a method for manufacturing the concrete.

[0002]

2. Description of the Related Art Concrete is obtained by kneading cement, water, sand and gravel in an appropriate ratio and hardening.
Among these materials, a mixture obtained by mixing only cement and water is called a cement paste, and a mixture obtained by adding sand to the mixture is called a mortar. Of the materials from which concrete is made, cement is the most important, and over 90% of the cement currently used is Portland cement.

[0003] Aggregates, such as gravel and sand, bonded by cement paste are called aggregates, which are classified into fine aggregates (5 mm or less) and coarse aggregates (5 mm or more) according to their sizes. In addition, admixture may be added to concrete as needed. Reinforced concrete reinforced with steel bars is called reinforced concrete.

[0004] The ratio of cement, water and aggregate in concrete is called blending. Conventionally, the ratio of cement, sand, and gravel is represented by a volume ratio such as 1: 2: 4 or 1: 3: 6 to express the composition. It was difficult to always measure an accurate amount due to the effect of increasing the amount to include. Therefore,
At present, the amount of material (unit amount) required to make 1 m ³ of concrete is indicated. For 1: 2: 4 concrete, the unit cement amount is about 320kg, 1: 3:
6 is about 250 kg.

[0005]

It is desirable to use high quality river sand as fine aggregate for concrete. However, even now, in the Kinki, Chugoku, Shikoku and Kyushu regions, sea sand occupies most of the fine aggregate instead of river sand. Use of sea sand is 1
It began at the same time as the rapid growth of aggregate demand accompanying the rapid economic growth in the mid 960s and the depletion of high quality aggregate in river sand.

[0006] By using sea sand as fine aggregate,
Deterioration of concrete structures due to salt damage occurs. Specifically, reinforcing steel is corroded mainly by chlorides mixed in from sea sand and other materials during the production of concrete. At present, in addition to regulations on the amount of chlorides in fine aggregate, regulations on the total amount of chlorides in concrete have been taken as a countermeasure, but at present it is not a fundamental measure.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses stone powder instead of sea sand to prevent crushed stone and stone powder in order to prevent salt damage caused by sea sand. And concrete manufactured using lime and cement, and a method for manufacturing the same. As for the composition, 300 to 500 kg of cement per 1 m ^{3 of} concrete is used.
m ³ , crushed stone 1500 kg / m ³ , stone powder 300-400 kg
/ M ^3, a concrete manufactured using 5-20% of cement weight lime. In addition, the particles of the crushed stone are set to be 2 to 7 mm smaller than the conventional crushed stone.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. The cement used in the present invention is usually Portland cement or blast furnace cement. As the crushed stone, a crushed stone having a size of 2 to 7 mm smaller than particles of a generally used crushed stone (5 to 20 mm) is used. Fine powder of limestone is used as the stone powder. As the lime, quick lime (calcium oxide) or slaked lime (calcium hydroxide) is used.

Regarding the ratio of cement, stone powder, crushed stone, and lime in the concrete production according to the present invention, the amount (unit amount) of the material necessary to make 1 m ³ of concrete is shown.
Cement 300-500kg / m ³ , Stone powder 300-40
0 kg / m ³ , crushed stone 1500 kg / m ^{3 ,} lime is 5 to 20% based on the weight of cement.

[0010] Cement, stone powder and lime having a weight corresponding to the weight of the ready-mixed concrete to be produced and water having a weight corresponding to the ready-mixed concrete to be produced are charged into a concrete mixer and kneaded to produce mortar. Next, the amount of water in the mortar is detected, and the amount of water is compared with the amount of water corresponding to the mixing ratio of the ready-mixed concrete to be produced. A crushed stone having a weight corresponding to the weight is put into the concrete mixer and kneaded with a mortar to produce a ready-mixed concrete.

Although the general method for producing concrete has been described above, the present invention is not limited to this, and can be carried out by appropriately changing the crystallinity and the mixing ratio of the stone powder, crushed stone and lime to be used. Things.

[0012]

EXAMPLES Specific examples will be shown below to further clarify the features of the present invention. As a first embodiment, concrete 1
m ³ per ordinary portland cement 330kg /
m ³ , Okayama-produced stone powder (limestone powder) 330 kg / m ³ ,
Crushed stone (2-7mm) from Yumezen-machi, Hyogo Prefecture 1500kg / m
^3, and 15cm diameter with lime 16.5 kg / m ^3,
Three cylindrical test pieces having a height of 30 cm were prepared, and standard curing was performed on a 28-year-old material. The results of the compression strength test of this specimen were 38.5 N / mm ² and 37.1 N / mm, respectively.
mm ² , 39.0 N / mm ² , and the average value is 38.2 N
/ Mm ² . This value is equal to or greater than that of the conventional concrete compressive strength test. The weight per m ³ of the concrete according to the present invention is about 2177 kg, while the weight per m ^{3 of} the conventional concrete is 2400 kg.
g, which is 223 kg lighter than conventional concrete.

As a second embodiment, per 1 m ^{3 of} concrete, blast furnace cement is 400 kg / m ³ , stone powder (limestone powder) from Okayama Prefecture is 330 kg / m ³ , crushed stone (2-7 mm) from Yumezen-machi, Hyogo Prefecture is 1500 kg / m. ^3, and lime 20kg
^Three cylindrical specimens having a diameter of 15 cm and a height of 30 cm were prepared using / m ³ , and standard curing was performed on a 28-year-old material. The results of the compressive strength test of this specimen were 3
^{0.4N / mm 2, 33.4N / mm} 2, 33.2N / m
m ² , and the average value was 32.3 N / mm ² . This value is equal to or greater than that of the conventional concrete compressive strength test. Further, with respect to 1 m ³ per weight of conventional concrete 2400 kg, 1 m of the concrete according to the invention
The weight per ³ was about 2250 kg, which was 150 kg lighter than the conventional concrete.

[0014]

The tree invention is constructed as described above,
Since concrete containing no sea sand can be manufactured, deterioration of the concrete structure due to salt damage to the reinforcing bars can be prevented. Moreover, since it is lighter than conventional concrete and the particles of crushed stone are as small as 2 to 7 mm, it is suitable for high-rise buildings, small structures, thin and narrow places, and the like.

Claims (5)

[Claims] 1. Concrete produced using crushed stone, stone powder, lime and cement. 2. The concrete according to claim 1, wherein blast furnace cement is used as the cement. ^3. Cement 3 per m ^{3 of} concrete
00~500kg / m ^3, stone powder 300~400kg /
m ³ , crushed stone 1500 kg / m ^{3 ,} lime is 5% of cement weight
The concrete according to claim 1, wherein the concrete is manufactured using 20%. 4. The concrete according to claim 1, wherein the crushed stone has a particle size of 2 to 7 mm. 5. A method for producing concrete using crushed stone, stone powder, lime and cement.