JPH11171608A - Concrete construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the effective utilization of salt-containing sea sand by adding cement and water to fine aggregate mainly comprising sea sand, kneading the mixture together with an inorganic curing agent and by allowing the aggregate mix to concrete. SOLUTION: The inorganic curing agent is, for example, the NSC curing agent (for civil engineering) produced by New Soil Chemical Co. The proportion of the sea sand is preferably set up to 80-90%. In the case that the amount of Cl in the sea sand is 6.24 g/kg on the dry basis (10.3 g/kg calculated as NaCl), the elution of Cl from the sample of 20-days age can be suppressed to 0.39 g/l (0.65 g/l calculated as NaCl), even when the proportion of the sea sand is set to 90%. When, the cement-water ratio is set to 0.85-1.1 in the case that the sea sand proportion is 90%, the fineness moduli of sea sand and land sand is to 1.85 and 1.80 respectively, and has a specific gravity of 1.27 and 2.10, respectively, the compression strength of 5-10 N/mm<2> can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete method using fine aggregate mainly composed of sea sand, which can be widely applied to road pavements, buildings, concrete secondary products and the like.

[0002]

BACKGROUND OF THE INVENTION Sea sand is generally considered unsuitable as aggregate for concrete. Sea sand contains salt in seawater, and the reinforcing steel bar may be attacked by the salt, and the concrete may deteriorate due to the alkali-aggregate reaction.If a large amount of salt elutes from the concrete structure after construction, This can corrode related steel structures and become a new source of pollution.

[0003]

However, river sand, land sand, mountain sand, etc. that do not contain salt (hereinafter simply referred to as land sand).
Due to limited harvesting areas and yields, it is unavoidable that raw material costs, including transportation costs, tend to rise more and more. In addition, at present, crushed sand produced as a by-product of a crushed stone plant or by a dedicated sand-making plant has a small production amount and has not yet reached generalization.

Accordingly, an object of the present invention is to provide a concrete construction method in which sea sand containing salt can be effectively used by adding an inorganic hardening agent.

[0005]

According to the structure of the present invention for achieving the above object, cement and water are added to fine aggregate mainly composed of sea sand, an inorganic hardening agent is added, and the mixture is kneaded. The main point is to establish

The fine aggregate is composed of 80 to 90% of sea sand and 2 of land sand.
It may be 0 to 10%, and the cement water ratio is 0.85 to
It may be set to 1.1.

[0007]

[Action] When due to configuration of the invention, inorganic hardener, Na ^+, K ⁺ containing, Co ^+, Cl - ^by, ammonium salt coexists with cement, enable salt contained in sand on which can be fixed to, accelerate the condensation of cement milk, it is possible to accelerate the curing, be charged a large amount of sea sand as fine aggregate, Cl cured ^- sufficiently reduce the elution amount be able to. Here, the inorganic hardener is, for example, an NSC hardener (for civil engineering) manufactured by New Soil Chemical Co., Ltd., located in Soja City, Okayama Prefecture.

The ratio of sea sand and land sand in the fine aggregate can increase the economic effect as the former increases, but the workability at the time of construction is improved by improving the water retention of the fine aggregate. enhanced, thereby improving the strength, even when the amount of salt is larger contained in sea sand, Cl cured ^- in order to sufficiently reduce the elution amount, keep the ratio of sea sand to 80-90% Is preferred. Incidentally, Cl contained in sea sand ^- dry weight value is in the 6.24 g / kg (NaCl converted 10.3
g / kg), even if the sand content is 90%,
Cl from day 0 samples ^- the elution amount of 0.39 g / l
(0.65 g / l in terms of NaCl).

[0009] The cement water ratio should be appropriately determined according to the strength data obtained from the test kneading. Sea sand ratio 90
%, Sea sand and land sand have coarse grain ratios of 1.85 and 1.80, respectively.
When the specific gravity is 2.62 and 2.53 and the water absorption is 1.27 and 2.10, respectively, the compression ratio is set by setting the cement water ratio to c / w = 0.85 to 1.1. Strength m = 5 to 10 N / mm ² can be realized.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A concrete test piece 1 was manufactured using fine aggregate mainly composed of sea sand from Komaiko, Mikawa-machi, Ishikawa-gun, Ishikawa (Fig. 1).

The test piece 1 has a width of 3500 mm and a length of 5000
mm and a thickness of 100 mm.

The concrete composition of the test piece 1 is as shown in FIG. That is, the cement water ratio c / w = 0.
And 95, fine aggregate is small Maiko production of sea sand 90%, and 10% mountain sand of Fukui Prefecture, Sakai-gun Awara-cho Kitagata production, as the unit quantity, ordinary cement 281kg / m ^3, water 295kg / m ^3, sea Sand 145
In addition to 3 kg / m ³ and land sand 156 kg / m ³ , 18 l / m ³ of NSC hardener (for civil engineering) was added to fully satisfy the slump 8 cm and the design strength of 6.5 N / mm ^2. Was. In addition,
Using this fine aggregate, sea sand 80-90%, land sand 20-1
FIG. 3 shows the results of the test kneading at 0%. According to this, the compressive strength m = 5 to 10 N / mm ² can be satisfied at the cement water ratio c / w = 0.85 to 1.1. However, the coarse particle ratio, specific gravity, and water absorption of sea sand and land sand are as described above.

FIG. 4 shows a procedure for manufacturing the test piece 1. That is, sea sand is collected, transported to a concrete plant, and kneaded. It is carried into the production site by a concrete mixer truck and cast. Thereafter, the sheet was cured and cured.

Since the present invention is mainly made of sea sand, if it is applied as a promenade on the coast, it can provide a landscape integrated with the foreshore using local sand, has low thermal conductivity, and has a low summer light. The return is not strong and the walking feeling is soft. Further, it can be widely applied not only to roads but also to buildings and concrete secondary products, and the amount of salt contained in sea sand can be sufficiently reduced as described above.

[0015]

As described above, according to the present invention, by adding cement and water to fine aggregate mainly composed of sea sand and adding an inorganic hardening agent, the inorganic hardening agent is
Since the amount of salt contained in sea sand is fixed and the amount of elution after curing can be sufficiently reduced, the excellent effect of effectively utilizing sea sand containing salt and compensating for the shortage of land sand can be achieved. is there.

[Brief description of the drawings]

FIG. 1 is a perspective view of a test piece.

[Fig. 2] Concrete mix chart

FIG. 3 is a diagram showing test kneading data;

FIG. 4 is a manufacturing process diagram of a test piece.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuro Naya 5-85, Izumotocho, Kanazawa-shi, Ishikawa Prefecture Inside the Kanazawa Construction Office of the Hokuriku Regional Construction Bureau, Ministry of Construction (72) Inventor Akira Takahashi No. 46 in the company ecosystem

Claims (3)

[Claims] 1. A concrete method characterized by adding cement and water to fine aggregate mainly composed of sea sand, adding an inorganic hardening agent, kneading and pouring. 2. Fine aggregate is 80 to 90% of sea sand and 20 to 90% of land sand.
The concrete method according to claim 1, wherein the content is 10%. 3. The concrete method according to claim 2, wherein the cement water ratio is set to 0.85 to 1.1.