Labor-saving method for surface treatment of reinforced concrete slabs

Abstract

To provide a method of saving labor for the surface treatment of a reinforced concrete floor slab during construction of a bridge surface concrete pavement.SOLUTION: There is provided a labor saving method for surface treatment of a reinforced concrete floor slab that treats the surface in a range within 1 m from both ends of a reinforced concrete floor slab. Preferably, the surface treatment is a water jet and / or shot blast. More preferably, the average depth of the unevenness of the reinforced concrete floor slab formed by the surface treatment is 1 mm or more.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for reducing the labor required for surface treatment of reinforced concrete decks during construction of a bridge deck concrete pavement. [Background technology]

[0002] Since concrete pavement on bridge decks is subject to greater displacement than pavement on earthworks, strong adhesion between the pavement and the reinforced concrete deck is required during construction. To strengthen the adhesion, adhesives are used (Patent Document 3) and surface treatments are performed using water jets (Patent Documents 1, 2, and 4) and shot blasting (Patent Document 3). However, applying such surface treatments to the entire bridge surface increases construction costs and labor. [Prior art documents] [Non-patent literature]

[0003] [Patent Document 1] Patent Publication No. 2016-61071 [Patent Document 2] Patent Publication No. 2013-60791 [Patent Document 3] Patent Publication 2008-179993 [Patent Document 4] Patent Publication No. 2006-161314 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a method for reducing the labor required for surface treatment of reinforced concrete decks during construction of bridge deck concrete pavement. [Means for solving the problem]

[0005] In order to study a labor-saving method that meets the above-mentioned objective, the inventors performed a temperature stress analysis of the concrete pavement on the bridge deck, and discovered that tensile stress occurs at the ends of the bridge. Based on this knowledge, they discovered that labor-saving can be achieved in the surface treatment of the reinforced concrete deck during construction of the bridge deck concrete pavement by performing surface treatment only on the ends of the reinforced concrete deck, and thus completed the present invention. That is, the present invention is a labor-saving method for surface treatment of reinforced concrete deck having the following configuration.

[0006] [1] The area within 1 m from both ends of the reinforced concrete deck in the axial direction of the bridge (from one bridge entrance to the other) is treated with water jets and / or shot blasting to reduce the average depth of the unevenness of the reinforced concrete deck to 1.08 to 4.11 mm. The thickness of the styrene-butadiene rubber latex-modified quick-hardening concrete is then increased by 5 to 6 cm, increasing the bond strength between the bridge deck concrete pavement and the reinforced concrete deck to 1.0 N / mm 2 The above-mentioned labor-saving method for surface treatment of reinforced concrete floor slabs is characterized by the above. (However, the area to be surface treated by the above water jet and / or shot blasting is limited to within 1m from both ends of the reinforced concrete deck in the axial direction of the bridge (from one bridge entrance to the other).) . Effect of the Invention

[0007] According to the present invention, it is possible to reduce the labor required for surface treatment of reinforced concrete decks during construction of bridge deck concrete pavement. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of changes in outdoor temperature over time in Naha during the summer. [Diagram 2] FIG. 1 is a diagram showing an example of changes in outdoor air temperature over time in winter in Hakodate. [Diagram 3] FIG. 1 is a diagram showing an example of changes in relative humidity over time in summer in Naha and winter in Hakodate. [Figure 4] This is a diagram showing an example of the range where warping stress occurs (the lighter black areas at both ends in Fig. 4). The conditions set were a bridge length of 30 m, a deck thickness of 20 cm, and the change in outside air temperature over time in Naha during the summer (Fig. 1). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The labor-saving method for surface treatment of reinforced concrete floor slabs according to the present invention will be described in detail below. In this labor-saving method, only the ends of the reinforced concrete slabs are surface-treated. By surface-treating only the ends of the reinforced concrete slabs, it is possible to reduce the labor required for surface treatment of the reinforced concrete slabs during construction of the bridge deck concrete pavement. The surface treatment may be water jet and / or shot blasting. In addition, the average depth of the unevenness of the reinforced concrete slab due to the surface treatment is 1 mm or more. If the average depth of the unevenness is 1 mm or more, the bond strength between the bridge concrete pavement and the reinforced concrete slab is the target strength of 1.0 N / mm, as shown in Table 1 below. 2 That's all. EXAMPLES

[0010] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. 1. Analysis of warping stress occurring in bridge concrete pavement on reinforced concrete deck using latex-modified rapid hardening concrete The subject of the analysis was a reinforced concrete girder bridge with a 5 cm thick layer of latex-modified rapid-hardening concrete on a reinforced concrete deck. The analysis was carried out by setting bridge lengths of 10, 20, and 30 m, deck thicknesses of 15 cm and 20 cm, and combining these with temperature and humidity data from summer in Naha City, Okinawa Prefecture (Fig. 1) and winter in Sapporo City, Hokkaido (Fig. 2), for a total of 3 x 2 x 2 = 12 different conditions. Figure 3 shows the time-dependent changes in relative humidity in summer and winter. The compressive strength of the existing floor plate is 24N / mm 2 , 70N / mm for latex-modified fast-hardening concrete 2It was also assumed that the drying shrinkage of the existing deck had been completed, and drying shrinkage was taken into account only for the latex-modified rapid-hardening concrete, using the shrinkage prediction formula of the Japan Society of Civil Engineers (Formula A below). For the outside air temperatures of the sides and underside of the bridge, temperature data from the Japan Meteorological Agency was used, while for the topside of the bridge, an equivalent outside air temperature that took into account the effects of solar radiation was used. The analysis period was a total of 31 days, and for the first three days, the analysis was conducted without taking into account the drying shrinkage of the latex-modified rapid-hardening concrete in order to make the temperature distribution of the bridge closer to reality, and for the following 28 days, the analysis was conducted with drying shrinkage taken into account. The software used for the above analysis was ASTEA MACS (manufactured by Computational Mechanics Research Center). The analysis results are shown in Figure 4. TIFF0007664679000001.tif57151

[0011] As shown in Fig. 4, the warping stress generated at the interface between the reinforced concrete deck and the latex-modified rapid-hardening concrete was highest within a range of 1 m from both ends of the interface between the reinforced concrete deck and the bridge deck concrete pavement. This shows that surface treatment using water jets or shot blasting should be performed within a range of 1 m from both ends of the reinforced concrete deck. The remaining 11 analysis results are omitted because they are the same as those in Figure 4.

[0012] 2. Measurement of adhesion strength (1) Materials used (i) Cement (abbreviation: C) Ordinary Portland cement (manufactured by Taiheiyo Cement Corporation) (ii) Fine aggregate (abbreviation: S) Mountain sand (Kakegawa City, Shizuoka Prefecture) (iii) Coarse aggregate (abbreviation: G) Crushed stone 2005 (from Sakuragawa City, Ibaraki Prefecture) (iv) Rapid hardening admixture (abbreviation: F) Facet (manufactured by Pacific Materials) (v) Latex mixture (abbreviation: L) Styrene-butadiene rubber latex (manufactured by Pacific Materials Co., Ltd.) (vi) Water (Abbreviation: W) Tap water

[0013] 2. Preparation of specimen Base layer concrete (thickness 60 mm) prepared by conventional methods was poured into a formwork and sheet cured until the material age was 7 days. The surface of the base layer concrete was then shot blasted or water jet treated as shown in Table 2 to obtain the texture depth shown in Table 2, and the surface of the base layer concrete was then moistened with water. Next, according to the mix ratio in Table 1, the cement, fine aggregate, coarse aggregate, and rapid hardening admixture were put into a forced mixing mixer and mixed for 15 seconds, after which water containing dissolved latex admixture was added and mixed for 120 seconds to prepare latex-modified rapid hardening concrete. This latex-modified rapid hardening concrete was then put on top of the base concrete to prepare test specimens measuring 1000 mm long x 1000 mm wide x 120 mm thick (the thickness of both the base concrete and the latex-modified rapid hardening concrete was 60 mm).

[0014] [Table 1]

[0015] 3. Measurement of adhesion strength The bond strength was measured by taking a core of 100 mm in diameter from the specimen at 40 days of age and carrying out a double pull test. The results are shown in Table 2.

[0016] [Table 2]

[0017] As shown in Table 2, if the average depth of the unevenness (grain depth) of the reinforced concrete slab formed by the surface treatment is 1 mm or more, the bond strength between the bridge concrete pavement and the reinforced concrete slab will be the target strength of 1.0 N / mm 2 That's all.

Claims

【Request 1】 The area within 1 m from both ends of the reinforced concrete deck in the bridge axial direction (from one bridge entrance to the other) is surface treated with water jet and / or shot blasting to set the average depth of the unevenness of the reinforced concrete deck to 1.08 to 4.11 mm, and then the thickness of the styrene-butadiene rubber latex modified quick-hardening concrete is increased by 5 to 6 cm, increasing the bond strength between the bridge deck concrete pavement and the reinforced concrete deck to 1.0 N / mm ２ A labor-saving method for surface treatment of reinforced concrete slabs, characterized by the above-mentioned (however, the area surface-treated by the water jet and / or shot blasting is limited to an area within 1 m from both ends of the reinforced concrete slab in the bridge axial direction (the direction from one bridge entrance to the other bridge entrance)).

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