JPH04139045A - Fiber reinforced rolled concrete - Google Patents

Abstract

PURPOSE:To improve the durability of rolled concrete over a long period of time by incorporating a prescribed amt. of org. monofilaments having a prescribed size and a prescribed aspect ratio as a reinforcing material into the concrete used for paving a road. CONSTITUTION:This fiber reinforced rolled concrete contains 0.3-3vol.% org. monofilaments such as polyvinyl alcohol fibers or polyacrylo-nitrile fibers. The monofilaments have 1,000-8,000 denier size and >=40 aspect ratio (length/ diameter).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention aims to prevent dry cracking, improve physical properties, and increase long-term durability by adding organic fibers as a reinforcing material to compacted concrete used in road paving methods. This relates to concrete pavement that has properties.

<Conventional Technology> Road pavements are broadly divided into asphalt concrete pavements and cement concrete pavements, and each is used depending on its advantages.

The former has many advantages over cement concrete pavement, such as economic efficiency during construction, workability, runnability, and ease of repair, but on the other hand, it lacks long-term durability, fluidity, and abrasion resistance, and is especially suitable for heavy traffic. The ruts seen on the route affect the layers below the surface, and their repair not only causes traffic congestion, but also often poses problems for driving safety.

Although the latter type of concrete pavement is recognized for its abrasion resistance and durability, its construction performance is decreasing year by year due to problems in workability and economy, and the ratio is 93% for expressways compared to asphalt pavement. Concrete pavement accounts for 7%.

In order to solve these problems, a construction method called ``Roll Concrete Method'' (hereinafter abbreviated as RCCP method) was devised that combines the advantages of both methods.

The advantages of the RCCP method are 1) Asphalt construction machines can be used and are economical.

2) Excellent load-carrying capacity at the time of initial order, allowing for early opening to traffic.

3) Since the amount of cement per unit is small, drying shrinkage is small and the spacing between joints can be expanded.

The RCCP method is becoming popular due to its design theory, ease of construction, and long-term stability.

<Problem to be solved by the invention> The concrete used in the RCCP method is unreinforced concrete, and although the compressive strength of the concrete itself is ensured, the bending strength and shear strength are weak, and it is difficult to avoid insufficient strength due to the wheel load of a heavy vehicle. It doesn't happen.

<Meeda's Means for Solving the Problems> The present invention is capable of forming fibers by adding organic monofilaments having a fineness of 1000 to 8000 deniers and an aspect ratio of 40 or more in a volume ratio of 0.5 to 3% to the resulting concrete. The key point is that we have developed concrete that can be reinforced with the RCCP method.

The details will be explained below.

What is important with the fiber-reinforced RCCP method is to ensure workability equivalent to or better than the conventional RCCP method, while uniformly dispersing fibers into the matrix to provide a reinforcing effect against wheel loads. The fineness is 1000 denier or more and 8000 denier or less, the aspect ratio is 40 or more, preferably the fineness is 1500 denier to 4000 denier,
An aspect ratio of 40 to 400 is desirable.

If the IIt fiber density is less than 1000 denier, fiber poles (hereinafter abbreviated as FB) will occur during cross-wire, which is unfavorable in terms of workability and reinforcing properties.

In terms of reinforcement, if it exceeds 8,000 denier, the cut length becomes longer and the fiber diameter becomes thicker, resulting in an insufficient number of fibers required for reinforcement, resulting in a decrease in strength.

For effective reinforcement, the aspect ratio (fiber length ρrn/d to fiber diameter d) must be 40 or more. If the aspect ratio is less than 40, the strength will not increase. If it is too long, the dispersibility will deteriorate, so it is preferably 800 or less.

The fiber strength used is preferably 5 g/denier or more, more preferably 7 g/denier, from the viewpoint of ensuring physical properties such as bending strength and shear strength. If the fiber strength is less than 58/denier, the action of the fibers after initial cranking may be insufficient, resulting in a decrease in strength.

The fibers used are polyvinyl alcohol fibers,
Examples include polyacrylonitrile fibers, polyamide fibers, aramid fibers, polyester fibers, polyarylate fibers, and polyolefin fibers, but polyvinyl alcohol fibers (hereinafter abbreviated as PVA fibers) are particularly good. Further, these fibers may be used in combination.

PVA fiber has an OH group and is hydrophilic, so it has extremely good adhesion with matrix components. When used as a reinforcing material, the bending strength of the cured product increases, the toughness is significantly improved, and the impact resistance is improved. It is an excellent material.

The compaction concrete referred to in the present invention is a zero slump cemented carbide concrete, and the mix varies depending on the aggregate, but the water/cement ratio (hereinafter abbreviated as W/C) is 30 to 30.
40% by weight, fine aggregate/total aggregate (hereinafter abbreviated as S/a) 30-50% by weight, cement amount 200-300k
g/m3, preferably w/c of 33-38 wt%, s/a of 35-45
The concrete has a weight percent cement amount of 250 to 300 kg/+a''.

As the cement, common cements are used, such as Portland cement, blast furnace cement, silica cement, fly-a-thonyu cement, and the like.

Fine aggregates include various types of sand from land and sea with a maximum length of 4 mm or less,
Crushed stone powder is used.

Various types of coarse aggregates having a maximum major axis of 5 to loomffi are used as the coarse aggregate.

As an admixture, an AE agent, a fluidizing agent, a water reducing agent, a thickening agent, a water retaining agent, a water repellent, etc. can be mixed.

As described above, the present invention uses monofilament organic fibers as reinforcing materials to achieve high strength and toughness without changing conventional formulations, construction materials, and construction methods, and achieves rolling compaction with good long-term durability and wear resistance. This led to the development of concrete.

Next, examples of the present invention will be shown.

The concrete mix used in this example had a W/C of 37
Weight%, s/a is 44% by weight, early strength Portland cement 297kg/+m'', water 110kg/+a'', river sand 943kg/m' as fine aggregate, gravel with a maximum particle size of 15mm as coarse aggregate 1200kg/m' , AE water reducer 1
．． The weight was 485 kg/m', and Kuraray's vinylon filament FR series was used as the reinforcing fiber.

(2) Kneading/forming method The mixture was kneaded for 15Q using a tilting mixer with a capacity of 3OQ. The kneading method is to first mix cement + gravel + sand + water reducing agent to create plain concrete, and then add reinforcing fiber PVA fiber brand RF 4000drX 30mm on top of it.
Other materials were added all at once, and the crosstalk, FB occurrence, and fiber dispersion were investigated. The results are shown in Table 1.

The rolling standard for plain RCCP method is design density
O, 96 times (ex 2.456X0.96=2.3
587/M”) is set as a tentative guideline.

The present invention is a steel formwork (inner capacity 10cmX lOc+aX
40cm), 2.456g/aII3X 40
00cm'

2) Physical property value lOcmX kneaded and molded according to the formulation shown in Table 1
The bending strength and compressive strength of a 40 cm specimen were measured.

A 200 TON hydraulic universal testing machine was used as the testing machine.

The measurement method is a bending test using a specimen (IOX IOX 40
), the bending toughness was determined by calculating the toughness up to a deflection of 0.2 cm on the obtained bending-deflection curve and using a magnification of 1 for the plain (Comparative Example 1).

The compression test was measured using a specimen Φ100X 200H. The results obtained are shown in Table 1.

As shown in Table 1, the monofilament-reinforced concrete of Example 1.2 can be mixed smoothly even with RccP's typical zero slump mix, and exhibits good operability. 50% increase, toughness is 6 times higher, withstands repeated running and cracking due to heavy lifting, and shows the possibility of thinning.

Comparative Example 1 This is an example in which reinforcing fibers were not mixed into the concrete used in Example 1 (referred to as plain).

Comparative Examples 2 to 5 These are examples in which tests were conducted in the same manner as in Example 1 using the reinforcing fibers shown in Table 1. When the fineness, aspect ratio, and mixing amount of the reinforcing fibers were outside the range specified in the present invention, compacted concrete with excellent bending strength, bending toughness, and compressive strength could not be obtained.

(Margin below)

Claims (1)

[Claims] The fineness is 1000-8000 denier and the aspect ratio is 4.
0.5 to 3% by volume of organic monofilaments of 0 or more
Contains compacted concrete.