JP6148376B1 - Clinker aggregate and cement concrete using it - Google Patents

Abstract

[PROBLEMS] To provide a clinker aggregate having good fluidity of cement concrete, high bending strength, and inhibiting chloride ion permeation, and cement concrete using the same. A clinker having a coarse particle ratio of 2.0 to 3.5, a fine particle content of 0.15 mm or less is 10% or less, a CaO component is 15 to 40% by mass, and an Al2O3 component is 55 to 75% by mass. aggregate. A clinker aggregate having a porosity of 10% by volume or less. Cement concrete using the clinker aggregate. [Selection figure] None

Description

  The present invention relates to an aggregate used for cement concrete.

In recent years, there has been great interest in the durability of concrete. One of the causes of deterioration of concrete structures is salt damage in which rebar corrosion becomes obvious due to the presence of chloride ions.
As a method for suppressing salt damage, various methods for imparting chloride ion penetration resistance to a concrete structure are known. For example, a method for reducing the water / cement ratio of a hardened concrete is known (see Non-Patent Document 1).
On the other hand, a method of improving chloride ion penetration resistance using a cement admixture has been proposed (see Patent Document 1). Moreover, the technique which improves durability of concrete using a clinker as an aggregate is also known (refer patent document 2).
However, the method of reducing the water / cement ratio has a problem that not only the workability is impaired but also a drastic measure is not taken. Moreover, mortar and concrete excellent in not only salt damage resistance but also crack resistance have been demanded.

Koichi Kishitani, Noriaki Nishizawa et al., Durability series of concrete, Salt damage (I), Gihodo Publishing, pp. 49-54, May 1986

Japanese Patent No. 5688073 Japanese Patent Laid-Open No. 2006-3149

The present invention provides a clinker aggregate and a cement concrete using the same, in which the fluidity of cement concrete is good, the bending strength is high, and the penetration of chloride ions can be suppressed.

That is, in the present invention, (1) the coarse particle ratio is 2.0 to 3.5, the fine particle content of 0.15 mm or less is 10% or less, the CaO component is 15 to 40% by mass, and the Al ₂ O ₃ component is Clinker aggregate of 55 to 75% by mass, (2) Clinker aggregate of (1) having a porosity of 10% by volume or less, and (3) Cement comprising the clinker aggregate of (1) or (2) Concrete.

  The cement concrete using the clinker aggregate of the present invention has the effects that the fluidity is good, the bending strength is high, and the penetration of chloride ions can be suppressed.

Hereinafter, the present invention will be described in detail.
In the present invention, “part” and “%” are based on mass unless otherwise specified.
The cement concrete referred to in the present invention includes mortar and concrete.

In the clinker aggregate of the present invention, the CaO component is preferably in the range of 15.0 to 40.0%, the Al ₂ O ₃ component is preferably in the range of 55.0 to 75.0%, and the CaO is in the range of 20.0 to 35. It is more preferable that 0% and Al ₂ O ₃ are 60.0 to 70.0%. Outside this range, the fluidity and strength development may be reduced, or the salt damage suppression effect may be small.
The main compounds of clinker aggregate of the present invention, and calcium aluminate such as _{12CaO · 7Al 2 O 3, CaO} · Al 2 O 3, CaO · 2Al 2 O 3, CaO · 6Al 2 O 3, MgAl 2 O ₄ is mentioned.

Examples of the raw material for producing the clinker aggregate of the present invention include limestone, slaked lime, and calcium metal as calcium raw materials. Examples of the aluminum raw material include bauxite, aluminum residual ash, and metal aluminum. General industrial raw materials contain impurities such as Fe ₂ O ₃ , TiO ₂ , K ₂ O, and Na ₂ O. These impurities may be present as long as they are in the range of 10% or less.

In the present invention, clinker aggregate is mainly used as fine aggregate. The coarse particle ratio serving as an index of the particle size distribution of the fine aggregate is preferably 2.0 to 3.5, more preferably 2.0 to 3.0. Further, the fine particle size of 0.15 mm or less is preferably 10% or less, more preferably 6% or less, and further preferably 3% or less. Outside the above range, the flowability of mortar and concrete may decrease, and the improvement of bending strength and the effect of inhibiting the penetration of chloride ions may not be obtained.

The porosity of the clinker aggregate of the present invention is preferably 10% by volume or less. The porosity can be measured by the Archimedes method. That is, after measuring the total volume and mass of the aggregate that has absorbed water, the aggregate is dried at 100 ° C. until the mass becomes constant, and the mass before and after drying is calculated as a void.
When the porosity of the clinker aggregate exceeds 10% by volume, the fluidity of the concrete is lowered, and the bending strength is not improved and the chloride ion permeation suppressing effect may not be obtained. In order to reduce the porosity, it is important to melt a clinker aggregate to form a dense structure.

The method for producing the aggregate of the present invention is not particularly limited, but the calcium raw material and the aluminum raw material are mixed, heated and further melted and cooled, the fired product is pulverized, and adjusted to an arbitrary size. It is preferable to do.
The clinker aggregate of the present invention can be prepared to an arbitrary size by pulverizing a clinker mainly composed of calcium aluminate produced as a by-product during various metal refining.

  The cement used in the present invention includes various portland cements such as normal, early strength, ultra-early strength, low heat, and moderate heat, various mixed cements in which blast furnace slag, fly ash and silica are mixed with these portland cements, municipal waste Waste-use cement (eco-cement) produced using incineration ash, sewage sludge incineration ash, etc., various filler cements mixed with limestone fine powder, blast furnace slow-cooled slag fine powder, etc., 1 of these Species or two or more can be used.

  In the present invention, blast furnace granulated slag fine powder, limestone fine powder, fly ash, silica fume, and other admixtures, setting modifier, expansion material, quick hard material, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE Water reducing agents, antifoaming agents, thickeners, rust inhibitors, antifreeze agents, shrinkage reducing agents, polymers, fibrous materials such as steel fibers, vinylon fibers and carbon fibers, clay minerals such as bentonite, and hydrotalcite One or more of the group consisting of additives such as anion exchangers, known additives used in ordinary cement materials, fine aggregates, coarse aggregates, etc. are substantially inhibited. It can be used in combination as long as it is not.

"Experiment 1"
Using limestone and bauxite as raw materials, raw materials were prepared so as to have chemical components shown in Table 1, and melted at 1600 ° C. using an electric furnace to synthesize calcium aluminate clinker. Some of them were synthesized at a firing temperature of 1400 ° C. or calcium aluminate by-produced in the process of metal refining. The particle size of these clinker was adjusted with a pulverizer , the coarse particle ratio was 2.30, and the fine particle amount of 0.15 mm or less was 5%. Commercial limestone and quartzite aggregates were used for comparison.
Mortar was prepared using these aggregates as fine aggregates. The blending was performed by blending 225 parts of fine aggregate and 50 parts of water with respect to 100 parts of cement. After molding into a mold, the bending strength of the test specimen and the penetration depth of chloride ions when immersed in salt water were measured.

<Materials used>
_{Limestone: CaO: 51.4%, Al 2} O 3: 0.9%, Fe 2 O 3: 0.8%, SiO 2: 2.7%, MgO: 2.1%, loss on ignition 41.4 %
_{Bauxite: CaO: 1.7%, Al 2} O 3: 76.5%, Fe 2 O 3: 1.7%, SiO 2: 6.8%, MgO: 0.9%, loss on ignition 41.4 %
Slag: Occurs during vanadium refining process. _{CaO: 31.3%, Al 2 O} 3: 57.6%, MgO: 3.94%, SiO 2: 4.4%, others: 2.76%.
Cement: Ordinary Portland cement, commercially available, Blaine value 3,200 cm ² / g, density 3.15 g / cm ³
Aggregate (1): silica sand, coarse particle ratio 2.83, density 2.67 g / cm ³
Aggregate (2): lime sand, coarse particle ratio 2.25, density 2.70 g / cm ³
Water: tap water

<Test method>
Coarse grain ratio: Measured according to JIS A1102.
Aggregate fine particles: Measured according to JIS A1103.
Chemical composition of aggregate: Measured according to JIS R 5202.
Aggregate porosity: measured by Archimedes method.
Mortar flow: Measured according to JIS R 5201.
Bending strength: According to JIS R 5201, the flow value of the specimen subjected to water curing at 20 ° C. until the age of 28 days is measured. Penetration depth of chloride ion: Water curing at 20 ° C. until the age of 28 days After the test, the specimen was immersed in simulated seawater (Daigo Artificial Seawater / Nippon Pharmaceutical Co., Ltd.) for 13 weeks, and the penetration depth of chloride ions was confirmed by the silver nitrate-fluorescein method.

From Table 1, the clinker aggregate of the present invention has a small influence on fluidity, shows a higher bending strength, and has a smaller chloride ion penetration depth than the case of using a normal aggregate. I understand that.

"Experimental example 2"
The test was conducted in the same manner as in Experimental Example 1 except that the aggregate of Experiment No. 1-5 was used and the coarse particle ratio of the aggregate and the amount of fine particles of 0.15 mm or less were changed.

From Table 2, the clinker aggregate of the present invention has a small influence on the fluidity, shows a higher bending strength, and has a smaller chloride ion penetration depth than when a normal aggregate is used. I understand that.

Cement concrete using the clinker aggregate of the present invention is suitably used in the field of civil engineering and construction because it has good fluidity, high bending strength, and the ability to suppress the penetration of chloride ions.

Claims (3)

A clinker bone having a coarse particle ratio of 2.0 to 3.5, a fine particle content of 0.15 mm or less is 10% or less, a CaO component is 15 to 40% by mass, and an Al ₂ O ₃ component is 55 to 75% by mass. Wood. The clinker aggregate according to claim 1, wherein the porosity is 10% by volume or less. Cement concrete using the clinker aggregate according to claim 1 or 2.