Stone block evaluating method

Abstract

To provide a stone block evaluating method, which can evaluate, through a single test, adhesion strength between a bottom surface of a stone block and a grout material, and filling properties of the grout material on the bottom surface of the stone block.SOLUTION: A stone block evaluating method according to the present invention includes measurement step S1 for measuring a skid resistance value (BPN) of the bottom surface of a stone block 10 through a skid resistance value test, conversion step S2 for calculating an arithmetic mean roughness (Ra value) and a root mean square roughness (Rq value) of the bottom surface of the stone block 10 from the BPN based on the correlation between the BPN and a road surface texture, and evaluation step S3 for evaluating the stone block as meeting a quality standard when the Ra value is equal to or greater than a first threshold value and the Rq value is equal to or less than a second threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating stone blocks, and more particularly to a method for evaluating a stone block that can evaluate the adhesion strength between the bottom surface of the stone block and a grout material and the filling property of the grout material at the bottom surface of the stone block by a single test. [Background technology]

[0002] A type of stone block paving called the "Inject Method (registered trademark)" is known as a paving method that ensures road surface strength for vehicle travel while also taking into consideration the landscape. Stone block paving is constructed by laying an injection layer made of crushed stone on top of the base pavement, laying rectangular cut stone blocks on the injection layer, and injecting CA mortar (cement asphalt emulsion mortar), which is made by mixing cement and sand with asphalt emulsion, into the joints between adjacent stone blocks and into the injection layer, and then restraining the stone blocks on five sides, including the sides and bottom, as the CA mortar hardens (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-371512 A Summary of the Invention [Problem to be solved by the invention]

[0004] Stone block pavements are constructed to ensure their durability by being restrained on five sides by CA mortar. Therefore, if the adhesion strength between the bottom of the stone block and the CA mortar is insufficient, the bottom of the stone block may peel off from the injected layer and be damaged by the repeated shaking of the stone block as vehicles pass by. The adhesion strength of stone blocks depends mainly on the roughness of the cut surface, but because stone is a natural material, it is not possible to ensure uniform quality. For this reason, it is necessary to select stone blocks that can ensure a certain adhesion strength. Generally, the rougher the cut surface of a stone block, the stronger the bond strength with CA mortar. However, because stone block paving is a method of filling CA mortar from the joints of the stone blocks to below the bottom surface, if the bottom surface is significantly uneven, the filling of the CA mortar will be hindered, and the block may become more likely to peel off. As described above, when evaluating stone blocks, two conflicting requirements must be met: a roughness that ensures a certain adhesive strength with CA mortar, and a flatness that does not hinder the flow of CA mortar; however, no such evaluation method has existed to date.

[0005] An object of the present invention is to provide a method for evaluating stone blocks that solves the problems of the prior art as described above. [Means for solving the problem]

[0006] The stone block evaluation method of the present invention is characterized by comprising a measurement step of measuring the skid resistance value (BPN) of the bottom surface of the stone block by a skid resistance value test, a conversion step of calculating the arithmetic mean roughness (Ra value) and root mean square roughness (Rq value) of the bottom surface of the stone block from the BPN based on the correlation between the BPN and road surface texture, and an evaluation step of evaluating the stone block as meeting a quality level if the Ra value is equal to or greater than a first threshold value and the Rq value is equal to or less than a second threshold value.

[0007] In the stone block evaluation method of the present invention, a road surface texture having a road surface wavelength of 0.5 mm or less may be used in the conversion step.

[0008] In the stone block evaluation method of the present invention, in the conversion step, the Rq value and the Ra value may have a relationship of [1.1Ra < Rq < 1.2Ra (Formula 1)]. Effect of the Invention

[0009] The stone block evaluation method of the present invention evaluates two conflicting quality conditions, namely, the adhesion strength between the bottom of the stone block and the grout material and the filling ability of the grout material at the bottom of the stone block, through a single slip resistance test, and can easily and objectively select stone blocks that meet the quality standards. [Brief description of the drawings]

[0010] [Figure 1] An explanatory diagram of the method for evaluating stone blocks according to the present invention. [Diagram 2] Illustration of stone block paving according to the present invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The method for evaluating stone blocks according to the present invention will be described in detail below with reference to the drawings.

[0012] [Evaluation method for stone blocks] <1> Overall configuration (Figure 1) The stone block evaluation method is a method for selecting stone blocks 10 for the stone block pavement 1 that meet a quality standard. The method for evaluating a stone block comprises at least a measuring step S1, a converting step S2, and an evaluating step S3. The method for evaluating stone blocks utilizes the correlation between skid resistance value (BPN) and road surface texture to evaluate the stone blocks 10. The correlation between skid resistance value (BPN) and road surface texture is discussed in detail in, for example, the following paper (Reference 1). [Reference 1] "Hidefumi Izuo et al., "Study on the relationship between skid resistance and road surface texture of concrete pavement", Proceedings of the Japan Society of Civil Engineers, Reiwa 3, Vol. 77 No. 2 (Pavement Lectures Vol. 26), I_145~I_153"

[0013] <1.1> Stone block pavement (Figure 2) The stone block pavement 1 is a pavement structure in which the road surface is made up of stone blocks 10. The stone block pavement 1 comprises a number of stone blocks 10 arranged in parallel, a granular layer 20 interposed between the bottom surfaces of the stone blocks 10 and the base pavement, and grout material 30 that binds five sides, including the sides and bottom surfaces, of the stone blocks 10. Stone block pavement 1 is constructed by laying crushed stone in a uniform thickness on a base pavement (e.g., asphalt pavement or concrete pavement) to create a granular layer 20 (inject layer), arranging rectangular stone blocks 10 in parallel on the granular layer 20, and filling the joints between the stone blocks 10 and into the granular layer 20 with grout material 30 (e.g., CA mortar). The filled grout material 30 permeates into the granular layer 20, adheres to the bottom surface of the stone block 10, and hardens to restrain the stone block 10 on five surfaces, including the sides and bottom.

[0014] <2> Measurement steps The measurement step S1 is a step for measuring the BPN of the bottom surface of the stone block. The BPN is measured by a skid resistance test using a pendulum type skid resistance tester (portable skid resistance tester). The testing machine comprises a main body, a scale plate attached to the main body, an arm with a pendulum structure rotatably supported on the main body, and a slider with a rubber piece attached to the tip of the arm. The bottom surface of the stone block 10 is placed facing up, the surface is moistened with water, and then a tester is placed on the stone block 10. Next, the slider is swung down to contact the bottom surface, and the resistance value at the time of contact is read on the scale as a measured value (BPN). The measurement is performed five times consecutively, and the average of the four values ​​excluding the first value is defined as the BPN.

[0015] <3> Road Texture Road texture is the surface structure of the road. Road surface texture can be quantified into various indicators by measuring it using a light-section measuring instrument, a laser displacement meter, a stylus-type surface roughness measuring instrument, etc. Numerical indices for road surface texture include arithmetic mean roughness (Ra value), root mean square roughness (Rq value), mean particle depth (MPD value), skewness (Rsk), and kurtosis (Rku).

[0016] <3.1> Arithmetic mean roughness The arithmetic mean roughness (Ra value) is one of the numerical indices of road surface texture, and is the average of the absolute values ​​of heights over a reference length (JIS B 0601). The larger the Ra value, the rougher the measurement surface.

[0017] <3.2> Root mean square roughness The root mean square roughness (Rq value) is one of the numerical indices of road surface texture, and is the root mean square of the height over a reference length, indicating the standard deviation of the height (JIS B 0601). A larger Rq value means that the roughness of the measurement surface varies more.

[0018] <4> Conversion Step The conversion step S2 is a step for determining the arithmetic mean roughness (Ra value) and the root mean square roughness (Rq value) of the bottom surface of the stone block 10 from the BPN. The Ra value and the Rq value can be obtained by utilizing the correlation between the BPN and the road surface texture. In detail, for example, the correlation data shown in FIG. 12 of Reference 1 can be used. JPEG2025066400000002.jpg99145 By applying the BPN measured in the measurement step S1 to the regression line related to "wear action" in the above graph, it can be converted into an Ra value. [Ra = (BPN-β) / α] In this example, a road surface texture with a road surface wavelength of 0.5 mm or less is used as the road surface texture. According to Reference 1, the Ra value with a road surface wavelength of 0.5 mm or less is particularly highly related to the BPN, so by using a road surface texture with a road surface wavelength of 0.5 mm or less, the Ra value and the Rq value can be converted more accurately. According to FIG. 9 in Reference 1, the Ra value and the Rq value are nearly directly proportional to each other, so the Rq value can be calculated by multiplying the Ra value by a proportionality coefficient. JPEG2025066400000003.jpg93148 From the above graph, for example, the proportionality coefficient by which the Ra value is multiplied can be selected within the range of 1.1 to 1.2 times.

[0019] <5> Evaluation Steps The evaluation step S3 is a step for evaluating whether the stone block 10 satisfies a quality standard. In the evaluation step S3, the stone block 10 is evaluated based on its Ra value and Rq value. The higher the Ra value, the rougher the bottom surface of the stone block 10 is, and therefore the stronger the adhesive strength with the grout material 30 is, whereas the lower the Ra value, the weaker the adhesive strength is. Therefore, it is necessary to set a lower limit (first threshold value) for the Ra value. The larger the Rq value, the more significant the unevenness of the bottom surface of the stone block 10 becomes, and the more likely it is that the flow of the grout material 30 is hindered. Therefore, in order to ensure the filling property of the grout material 30, it is necessary to set an upper limit (second threshold) for the Rq value. From the above, it is determined that the stone block 10 satisfies the quality standard, provided that the Ra value is equal to or greater than the first threshold value and the Rq value is equal to or less than the second threshold value. In addition, stone blocks 10 that do not meet the quality standards can be reevaluated after undergoing surface treatment such as high-pressure cleaning or shot blasting. [Explanation of symbols]

[0020] 1. Stone block paving 10 Stone Block 20 Granular layer 30 Grout material S1 Measurement step S2 conversion step S3 Evaluation Step

Claims

1. A method for evaluating stone blocks in a stone block pavement, the method comprising: arranging a plurality of stone blocks on a granular layer; injecting grout material into the joints between adjacent stone blocks and into the granular layer; and allowing the grout material to solidify. The method comprises: A measuring step of measuring the slip resistance value (BPN) of the bottom surface of the stone block by a slip resistance value test; A conversion step of calculating an arithmetic mean roughness (Ra value) and a root mean square roughness (Rq value) of the bottom surface of the stone block from the BPN based on a correlation between the BPN and a road surface texture; and an evaluation step of evaluating the stone block as meeting a quality standard when the Ra value is equal to or greater than a first threshold value and the Rq value is equal to or less than a second threshold value. How to evaluate stone blocks.

2. In the conversion step, a road texture having a road surface wavelength of 0.5 mm or less is used. A method for evaluating stone blocks according to claim 1.

3. In the conversion step, the Rq value and the Ra value are 1.1Ra < Rq < 1.2Ra... (Formula 1) The present invention is characterized in that: A method for evaluating stone blocks according to claim 1 or 2.

Images