KR101086980B1 - High-Strength Light weight Concrete - Google Patents

Abstract

The present invention relates to a high-strength lightweight concrete compounded by mixing the premix cement for high-strength expression, and formulated by combining the structural lightweight coarse aggregate and the non-structural lightweight fine aggregate.

The present invention is water, binders, coarse aggregates and fine aggregates unit amount of 140 ~ 170kg / ㎥; Unit binder content of 500 to 1100 kg / m 3; Unit coarse aggregate amount of 500 ~ 600㎏ / ㎥; And unit fine aggregate amount of 260 ~ 550㎏ / ㎥; It is mixed with, the water-bonding material ratio is 15 to 34% by weight, the fine aggregate content is 30 to 45% by weight, the binder is OPC, blast furnace slag powder, silica fume and preliminary retardant uniformly mixed premix cement, the coarse aggregate Is a structural light coarse aggregate, the fine aggregate provides a high-strength lightweight concrete, characterized in that the sand and the non-structured lightweight fine aggregate is mixed.

High strength concrete, lightweight concrete, premix cement, coarse aggregate, fine aggregate

Description

High-Strength Light Weight Concrete

The present invention relates to a high-strength lightweight concrete compounded by mixing the premix cement for high-strength expression, and formulated by combining the structural lightweight coarse aggregate and the non-structural lightweight fine aggregate.

Recently, as the structure becomes larger and more multifunctional, the performance improvement problem of construction materials for realizing ultra high-rise, extra-large, long span, special structures (offshore structures, etc.) has been of great concern. Existing concrete has lower strength and heavier weight than unit weight, so that the cross-section of structural member is enlarged and its use area is reduced, and environmental problems due to depletion and collection of natural aggregate are also highlighted. In order to solve the above problems, a variety of special concrete, such as lightweight concrete, high-strength concrete has been developed and used. A brief look at lightweight concrete and high-strength concrete is as follows.

Lightweight concrete includes lightweight aggregate concrete, lightweight foamed concrete, and muzan aggregate concrete. Among these, lightweight aggregate concrete is concrete made by mixing ordinary Portland cement and lightweight aggregate. Lightweight aggregates can be classified into structural and non-structural (insulation, soundproofing, etc.) structural artificial lightweight aggregates such as expanded shale, expanded clay, expanded slag, expanded coal, and processed coal. . Lightweight aggregates are light due to numerous voids in the interior, while high absorption rate not only causes slump reduction immediately after mixing, but also affects the quality of concrete before and after pressing due to pressure absorption due to the pressure acting upon pumping. There is a problem that makes a difference. For this reason, lightweight aggregates with very low absorption rate (5 to 8%) are often used in Europe, but light aggregates with high absorption rate (typically 10 to 30%) are widely used in Korea, the United States, and Japan for one to three days. It is a method of producing lightweight concrete through sufficient pre-wetting process. Pre-wetting lowers the absorption rate of lightweight aggregates, thereby minimizing the slump degradation caused by the movement of moisture from the matrix to the lightweight aggregates during pumping, reducing the quality change of concrete before and after pressing, and in the long term curing process Emission of moisture from light weight aggregates at a low temperature gives an effect of internal curing, which also helps the life of concrete.

On the other hand, according to the concrete standard specifications, high-strength concrete is set to 40Mpa or more, high-strength lightweight concrete is set to 27Mpa or more. It seems that about 50Mpa is commercialized in domestic high-rise buildings, and it is limited in the range of 80 ~ 100Mpa. As cement used for high strength concrete, portland cement, crude steel cement, alumina cement, silica cement, blast furnace slag (special type), fly ash cement (class A) and the like can be used. Aggregate should be physically (thermal, gaseous), chemical (carbonic acid, etc.) stable, dense, hard and free of harmful substances. Fine aggregates have a smooth circular surface shape and smooth surface that require less mixing water in concrete. It must be a durable aggregate.

The present invention is to provide a high-strength lightweight concrete that can reduce the weight of the structure by lowering the mass per unit volume while expressing a high strength performance of 40Mpa or more.

General concrete is composed of water, binders, coarse aggregates and fine aggregates. The present invention is applied to the premix cement as the binder in order to solve the above problems, to apply the light weight coarse aggregate for structural as the coarse aggregate, the non-structural light weight fine aggregate is applied as the fine aggregate.

According to the present invention, it is possible to obtain a high-strength and light weight concrete, thereby realizing both the durability of the structure and the weight reduction.

The present invention is water, binders, coarse aggregates and fine aggregates unit amount of 140 ~ 170kg / ㎥; Unit binder content of 500 to 1100 kg / m 3; Unit coarse aggregate amount of 500 ~ 600㎏ / ㎥; And unit fine aggregate amount of 260 ~ 550㎏ / ㎥; It is mixed with, the water-bonding material ratio is 15 to 34% by weight, the fine aggregate content is 30 to 45% by weight, the binder is OPC, blast furnace slag powder, silica fume and preliminary retardant uniformly mixed premix cement, the coarse aggregate Is a structural light coarse aggregate, the fine aggregate provides a high-strength lightweight concrete, characterized in that the sand and the non-structured lightweight fine aggregate is mixed.

In addition, the present invention, the premix cement is OPC 50 ~ 60% by weight; Blast furnace slag powder 30-40 wt%; Silica fume 5-15% by weight; And 0.1 to 5% by weight of the fastening delay agent; It provides a high strength lightweight concrete characterized in that the mixture.

In addition, the present invention, the water reducing agent is a unit reducing agent amount of 5 ~ 30kg / ㎥; It provides a high-strength lightweight concrete, characterized in that more mixed.

In addition, the present invention provides a high-strength lightweight concrete, characterized in that the light weight coarse aggregate is 1.5 ~ 1.9t / ㎥ a dry density.

In addition, the present invention provides a high-strength lightweight concrete, characterized in that the non-structured lightweight aggregate is mixed in 10 ~ 30% by volume compared to the total aggregate.

Hereinafter, the present invention will be described in detail with specific experimental data.

High-strength lightweight concrete according to the present invention is the above-mentioned premix cement (unit binding amount 500 ~ 1100㎏ / ㎥), structural lightweight coarse aggregate (unit coarse aggregate amount 500 ~ 600㎏ / ㎥) and fine aggregate (sand + non-structural lightweight fine aggregate, unit Residual aggregate amount of 260 ~ 550㎏ / ㎥) and water unit amount of 140 ~ 170 ㎏ / ㎥ is compounded. In this case, in order to improve the workability of concrete, a water reducing agent may be mixed, but the water reducing agent may be mixed only about 0.1 to 0.6% of the weight of the premix cement (unit water reducing agent amount of 5 to 30 kg / ㎥;), but The effect of improving durability and compressive strength is excellent.

The binder of the present invention is based on the use of a mixed cement having a higher strength than one type of ordinary portland cement (OPC), and pre-mixed high-molecular powder pre-mixed with the raw material of the mixed cement in advance. cement) was applied.

Premix cement applied to the present invention is OPC 50 ~ 60% by weight; Blast furnace slag powder 30-40 wt%; Silica fume 5-15% by weight; And 1 to 5% by weight of a fastening retardant; Is mixed, which has improved powder and compressive strengths compared to the one type of ordinary Portland cement (OPC).

[Table 1] below shows 55% by weight of OPC, 30% by weight of blast furnace slag, 10% by weight of silica fume, and 5% by weight of delayed retardant. Is a comparison.

[Table 1] Comparison of Properties of OPC and Premix Cement

division Powder Compressive strength (MPa) 3 days 7 days 28 days OPC 3,200 23.0 31.5 39.4 Premix Cement 6,400 38.8 50.4 62.4

In Table 1 above, the premix cement had twice the powder density compared to the OPC, and the 28-day compressive strength was about 1.5 times higher.

On the other hand, in order to reduce the weight of concrete, the weight of aggregates (coarse aggregates and fine aggregates), which occupies a volume of 70 to 80% of the concrete mix, must be achieved. Therefore, in Korea, one type of light concrete using coarse aggregates and light aggregates is generally used as light weight aggregates, and two kinds of light weight concretes are used as light aggregates as part or whole of aggregates. However, the compressive strength of concrete is greatly influenced by the strength of coarse aggregate, which accounts for about 40% of the total volume. Therefore, it is necessary to adjust the density of light weight coarse aggregate used for light concrete.

According to the compressive strength of concrete, the construction density of the structural lightweight coarse aggregate is shown in Table 2 below.

[Table 2] The relationship between the dry density of coarse aggregate and the compressive strength of concrete

Concrete compressive strength Dry density of light weight coarse aggregate 21 MPa or less Use coarse aggregate below 0.9t / ㎥ 21-27 MPa 1.0 ~ 1.3t / ㎥ 27-40 MPa 1.3 ~ 1.5t / ㎥ 40 MPa or more Aggregate use over 1.5 ~ 1.9t / ㎥

As can be seen from the above [Table 2] for the production of high-strength lightweight concrete with a compressive strength of 40MPa or more, it is preferable to use a structural lightweight coarse aggregate of 1.5 ~ 1.9t / ㎥ dry density. Examples of such lightweight coarse aggregates for structural use include expanded clays.

However, the use of structural lightweight coarse aggregates with a dry density of 1.5 to 1.9 t / m3 makes it difficult to manufacture lightweight concrete because there is a limit in reducing the unit bulk mass of concrete. Therefore, in the present invention, by replacing part of the sand with non-structured lightweight fine aggregate, the unit volume mass of the concrete is realized. The non-structural lightweight fine aggregate is preferably the dry density of 0.3 ~ 0.6t / ㎥, and the amount of replacing the sand with the non-structured lightweight fine aggregate is preferably 10 to 30% by volume compared to the total fine aggregate including sand. This is because the concrete compressive strength decreases clearly when it is substituted by more than 30% by volume.

Thus, the effect obtained by substituting part of the sand with non-structured lightweight fine aggregate can be confirmed through the following [Table 3] to [Table 6].

Table 3 below shows the mixing state of the general high-strength concrete embodiments, Table 4 shows the compressive strength and the unit volume mass of the above embodiments.

[Table 3] Mixing status of general high strength concrete comparative examples

Compounding strength W / B
(%) S / a
(%) Unit material amount (kg / ㎥) W C S G AD 50 32.0 44.0 165 516 694 595 6.19 60 26.0 42.0 165 635 618 575 7.62 80 15.0 32.0 165 1,033 382 546 25.83

W / B: Water-binding ratio S / a: Fine aggregate fraction

W: Unit Quantity C: Premix Cement

S: Natural sea sand

G: Lightweight coarse aggregate for structural use (cut density 1.60g / cm3)

AD: water reducing agent

[Table 4] Properties of general high strength concrete comparative examples

Compounding strength Compressive strength (MPa) Unit volume mass (kg / ㎥) 3 days 7 days 28 days Before hardening After curing 50 36.7 49.5 57.6 1,942 1,875 60 40.9 51.8 62.5 1,968 1,883 80 57.4 69.4 84.3 2,116 2,049

On the other hand, Table 5 below shows the blended state of the high-strength lightweight concrete embodiments, Table 6 shows the compressive strength and unit volume mass of the above embodiments. The high-strength lightweight concrete embodiments shown in [Table 5], except that a part of the sand of the components of the embodiments of Table 3 above are replaced with non-structural lightweight fine aggregate, and other mixing conditions are different from those of [Table 3]. The same was done.

[Table 5]-Formulation status of high strength lightweight concrete embodiments according to the present invention

Compounding strength W / B
(%) S / a
(%) Unit material amount (kg / ㎥) W C S1 S2 G AD 50 32.0 44.0 165 516 490 49 595 6.19 60 26.0 42.0 165 635 433 43 575 7.62 80 15.0 32.0 155 1033 229 36 546 25.83

W / B: Water-binding ratio S / a: Fine aggregate fraction

W: Unit Quantity C: Premix Cement

S1: Natural Sea Sand

S2: Lightweight fine aggregate for non-structural (cut density 0.6g / cm 3)

G: Lightweight coarse aggregate for structural use (cut density 1.60g / cm3)

AD: water reducing agent

[Table 6]-Physical properties of high strength lightweight concrete embodiments according to the present invention

Compounding strength Compressive strength (MPa) Unit volume mass (kg / ㎥) 3 days 7 days 28 days Before hardening After curing 50 36.5 46.9 56.4 1,820 1,759 60 39.3 52.0 62.0 1,847 1,786 80 55.7 66.0 80.4 2,011 1,965

Physical properties of the high-strength lightweight concrete embodiments configured in the blended state of Table 5 can be found in Table 6.

Comparing the above [Table 4] and [Table 6], the general high strength concrete and high strength lightweight concrete according to the present invention can be seen that there is a difference in weight of about 80 ~ 120㎏ per 1㎥, This difference leads to weight differences of several tons to tens of tons depending on the size of the building.

1 is a test report of the high-strength lightweight concrete embodiment according to the present invention. In the Korean Materials Testing Laboratory, the specimens within the scope of the present invention were subjected to the 28-day compressive strength test and the unit mass test according to KS F 2405 and KS F 2462. The unit mass was 1885 to 1895 kg / m 3, and it was found that the present invention satisfies both the weight reduction and high strength expression aimed at by the present invention.

1 is a test report of the high-strength lightweight concrete embodiment according to the present invention.

Claims (5)

Water, binders, coarse aggregates and fine aggregates in the unit quantity of 140 ~ 170㎏ / ㎥; Unit binder content of 500 to 1100 kg / m 3; Unit coarse aggregate amount of 500 ~ 600㎏ / ㎥; And unit fine aggregate amount of 260 ~ 550㎏ / ㎥; Is incorporated into the Water-binding material ratio is 15-34% by weight, fine aggregate ratio is 30-45% by weight, The binder is OPC, blast furnace slag powder, silica fume and premixed cement is a premix cement mixed uniformly, The coarse aggregate is light weight coarse aggregate, The fine aggregate is high-strength lightweight concrete, characterized in that the mixture of sand and non-structured lightweight fine aggregate. In claim 1, The premix cement is OPC 50 ~ 60% by weight; Blast furnace slag powder 30-40 wt%; Silica fume 5-15% by weight; And 1 to 5% by weight of a fastening retardant; High strength lightweight concrete, characterized in that the mixture. In claim 1, High strength lightweight concrete, characterized in that the water reducing agent is further mixed with a unit water reducing agent amount of 5 ~ 30㎏ / ㎥. In claim 1, Structural lightweight coarse aggregate is a high strength lightweight concrete, characterized in that the dry density is 1.5 ~ 1.9t / ㎥. In claim 1, The high strength lightweight concrete, characterized in that the non-structural lightweight aggregate is mixed in 10 ~ 30% by volume compared to the total fine aggregate.

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