JP2571436B2 - Concrete thickening method - Google Patents

Description

The present invention relates to a concrete thickening method for a concrete pavement road or the like.

(Prior Art) In recent years, repair and thickening work has been frequently performed due to a rapid increase in wheel digging due to wear of concrete pavement roads due to the spread of spiked tires and enlargement of vehicles, and the like.

As a concrete thickening repair method, the concrete surface is subjected to a base treatment for projecting a steel grain shot at a high speed to form an irregular surface on the concrete surface, dust generated by the base treatment is removed from the concrete surface and cleaned,
After that, it is common to cast new concrete.

(Problems to be Solved by the Invention) In the concrete thickening work described above, it is said that the degree of removal and cleaning of dust from the concrete surface after the foundation treatment affects the adhesion strength of new and old concrete.

However, the current standard for thickening concrete has no evaluation method after cleaning the ground treated surface, and the degree of cleaning differs depending on each site, and there has been a problem that stable adhesion strength between new and old concrete cannot be obtained.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and a high-speed projection of steel grain shots is used to prepare a concrete surface into an uneven surface having an average depth of 1.0 to 1.5 mm. A first step of removing the dust generated by the underlying treatment from the concrete surface forming the uneven surface, and a second step of pressing an adhesive tape against the cleaned concrete surface to adhere the residual dust to the tape. A third step of measuring the passing light amount or the light reflection amount of the peeled adhesive tape and repeating the second step and the following steps until the measured value becomes 70 or more, and the measured value becomes 70 or more. And a fourth step of placing new concrete on the cleaned concrete surface.

(Progress of the Invention) In view of the above-mentioned problems, the inventors have intensively studied a method for measuring the degree of cleaning of the concrete surface after the surface treatment, and as a result, to accurately know the degree of dust remaining on the surface of the surface treatment, It is concluded that this is achieved by transferring the dust on the surface as it is to the sheet and measuring the degree of dust on the sheet. First, the dust on the ground surface is left as it is. It was considered that the method of transferring the adhesive tape onto the sheet was achieved by pressing the pressure-sensitive adhesive tape against the base treatment surface to adhere the remaining dust to the pressure-sensitive adhesive tape, and peeling off the dust.

Further, as a method of measuring the degree of dust adhered to the adhesive tape, by sticking the adhesive tape to which the dust is adhered to the backing paper, by measuring the amount of light reflection or the amount of light passing through the adhesive tape by using a commercially available measuring device The following experiment was conducted on the assumption that an accurate result was obtained.

(Experimental example) Concrete based on the specifications of the concrete pavement road was poured with the specified composition shown in Table 1.

After 12 months, the concrete road surface has a particle size of 1.4m
Steel grain Shot blasting speed 80 m / S of m, was subjected to recovery of projection density 100 kg / when m ² in projection to a surface treatment obtained by forming the uneven surface of the average depth 1.2mm dust and projection material and occur simultaneously After washing with water, there was no residual dust.

Subsequently, the particle size of the collected dust is 10 to 30 μm,
Those having a specific gravity of 2.6 to 3.2 and a bulk specific gravity of 1.0 to 1.6 were sprayed on each of the predetermined sections while varying the spraying amount between 0 and 5.0 g / m ^{2 on} the cleaned base treated surface.

In this state, a wide tape manufactured by Nitto Co., Ltd. is pressed against the surface to be treated, and the dust on the surface is collected and attached to white paper with a whiteness of 80.
Nippon Denshoku Industries Co., Ltd., light reflection measurement device (CP61D-D
While measuring the amount of light reflection using 3), a new concrete having the composition shown in Table 2 was poured on the dust-sprayed concrete.

Table 3 shows the results of a bond strength test of the old and new concretes carried out based on the concrete bond strength test method proposed by the Building Research Institute of the Ministry of Construction 7 days after casting the new concrete.

According to the above experimental example, it was found that when the dust scattering amount was 0.1 g / m ² or less (light reflection amount 70 or more), the adhesion strength was 15 kg / cm ² and did not increase further.

Therefore, it is necessary to perform the cleaning of the under-treated surface until the light reflection amount becomes 70 or more.

In the experiment, the degree of cleaning was confirmed by measuring the amount of light reflection. However, the same effect can be obtained by measuring the amount of transmitted light by using a transparent backing sheet.

(Effect of the Invention) In the present invention, when concrete thickening is performed as described above, the degree of cleaning of the ground treatment surface is numerically accurately grasped and the new concrete is poured, so that the new and old concrete can be stabilized. A predetermined adhesive strength can be obtained,
The effect on the industry is significant.

Claims (1)

(57) [Claims] 1. A first step of subjecting a concrete surface to an irregular surface having an average depth of 1.0 to 1.5 mm by high-speed projection of steel grain shots, and removing dust generated by the underlying treatment from the concrete surface forming the irregular surface. The second step of cleaning, and peeling the tape after pressing the adhesive tape against the cleaned concrete surface to adhere the residual dust, and measuring the amount of light or the amount of light reflected by the peeled adhesive tape,
A third step of repeating the second step and the following steps until the measured value becomes 70 or more; and a fourth step of placing new concrete on the concrete surface cleaned until the measured value becomes 70 or more, Concrete thickening construction method.