Proceedings of 2nd International Symposium for Color Science and Art 2020-2021

Development of Structural Color Material Contributing toMaintenance Management of Social Infrastructure and its
Application in the Civil Engineering and Architecture Fields.
Toshihiro Hiejima, Takayuki Uchida, Hiroshi Jinnai, Tsuyoshi Moriyama,Rika Matsumoto, Mitsutoshi Okano, Noritoshi Nambu and Kazuyuki Hiraoka
Tokyo Polytechnic Univ., 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan
I-2. Experimental Section
The structural color pigments (SCP) were obtained fromToyo Aluminiums K. K., called “Chromashine”. Theurethane was used as the main ingredient. The weightratios of pigment and synthetic resin were 3:97. In thisproject, the two-type of concrete specimen were prepared;
the type (A) is directly applying SCP/urethane resin on theconcrete surface, the type (B) is applying theSPS/urethane resin on a first coat of retroreflective waterbased paint. In compressing the concrete by thecompression tester, the color change of concrete surface
was taken by using 4 K video camera. Thus, obtained
photographs was converted a color value in a color space
RGB to a corresponding color value in a CIE L*a*b* color
space which is not depend on a device.

ABSTRACTThis project constitutes of the two independent themes
related with the structural color materials. (I) The one is todevelop the structural color materials detecting the aging
degradation of building material as the change of color. (II)The other one is to develop the educational tool made it
possible to visualize and colorize the sounds. At first, wefound to reveal the change of color values of structural
color in CIE-L*a*b* color space during the compression
process of concrete specimens. Secondary, wedemonstrate the visualization and colorization of Chladni
patterns created by the structural color materials.
1. INTRODUCTION
Structural colors are responsible for many of the brilliant
colors we see in nature. The blue of the sky, the rainbow
of colors in an oil slick, the bright colors of peacockfeathers, the brilliant blue of a Blue Morpho butterfly, themetallic colors of certain beetles,
and the glimmering colors ofsome fish, are all due to structuralcolor. This project constitute of
the two independent themes
related with the structural color
materials. (I) The one is to develop the structural color
materials detecting the aging degradation of building
material as the change of color. (II) The other one is todevelop the educational tool made it possible to visualize
and colorize the sounds.

I-3. Results and Discussion
As show in Figure 1, both of type (A) and (B) retain thebrilliant metallic color despite of the roughness of concretesurface. However, the brightness in all type B weresignificantly improved comparing with those of type (A). In
this article, we wish to report the analysis results of theconcrete specimen coated with the golden pigment, which
exhibits the largest change of color values.

I. Development of Structural Color Material
Contributing to Maintenance Management of Social
Infrastructure and its Application in the Civil
Engineering and Architecture Fields.
I-1 Introduction
A fifty or more years has passed since the last Tokyo
Olympics. Most of the social infrastructures built at thattime are rapidly progressing their deterioration. It is very
important issues in Japan to construct the maintenancesystems for easily diagnosing the deterioration of social
infrastructures. We focus on the point that the structuralcolor materials exhibit the remarkably change of colors by
the structural damage and distortion, which cause with
applying a slight external stimulus such as pressure,temperature and vibration. In this study, we tried todevelop the structural color paint to diagnose the aging
deterioration of buildings as the change of color.

Figure 1. Photographs of the concrete surfaces applying
various Chromashine®, type A: left specimen, type B: rightone, in the same color.
Figure 2 shows the typical photographs of concretesurface coated with the gold pigments: they were taken tothe state before compression (a), and immediately before(b) and after (c) cracks in concrete. Unfortunately, both oftype (A) and (B) show no the remarkably change of color
during the compression process. In order to quantitatively
discuss the color change, image analyses were carried out
using Image J program. Figure 3 shows the histograms ofcolor values (L*, a*, b*) on type (A) and (B) to the state of29

Proceedings of 2nd International Symposium for Color Science and Art 2020-2021
reveals the various shapes or patterns characteristic of thevibrational mode of sounds.
If we can make Chladni figures colorized by using thestructural color materials, it could be an extremely effective
educational tool not only in experiencing scientific interest
but also on understanding in both of the interference oflight and the resonance of sounds for Japanese highschool students. In this study, we wish to demonstrate theChladni figures changing optical patterns according to thefrequency of sound and the angle of view.

(a), (b) and (c). Type (A) exhibits to kept the identical
histograms during the whole compression process.

II-2. Experimental Section
Chromashine® and silicon oil (1.5 cp) were added to asquare (20 x 20 mm2) ironplate container with athickness of 1 mm, vibratingby using a vibration
generator equipped with afunction generator. The
weight ratios of Chromashine® and silicon oil were
Figure 4. Experimental
1:20. Fig. 4 shows theequipment for soundexperimental equipment inimage (Chladni figure).
Col.lab Gallery.

Figure 2. Photographs of concrete surface applying
Chromashine® to the state of (a), (b) and (c), upper: type(A), lower: type(B) (See in text).
In contrast, type (B) was found to be changed the color
values L*, a* and b* due to the compression. In particular,
the chromaticity a* shifts toward the minus (green)
direction, while the b* shifts to the plus (yellow) direction.
This result obviously indicates to be changed the hue oftype (B) by applying the compression. At this stage,
however, we could not determine whether this change inhue cause to the signs of cracking or inclination ofconcrete specimen. Further investigations are in progressin our laboratory.

II-3. Result and Discussion
The Chladni figure strongly depends on not only thepigment type but also the material and size of the container,
can only resonating at a specific frequency. Whenchromashine® of green was used, the most vibrant chladni
figure was observed in all of pigments. As show in Fig. 5,
we finally succeeded in finding the specific frequencies
where reveal mysterious optical texture. We have put theworks of sound image on display at 6th Exhibition at theCol.lab Gallery, so please have a look at them.

Gray Luminance (Arb. Units)

Type (A)Gray Luminance (Arb. Units)

0204060
L*8060
L*80

100 -10010-2010-20a*-100b*1020Type (B)02040

100 -100a*0b*

20Figure 3. Histograms of color values (L*, a*, b*) on type (A)and (B) to the state of (a): ■, (b): ■ and (c): ■, (See intext).
II Development for Coloring of the Mysterious
Geometric Pattern "Chladni Figure" Made by Sound
with Using the Structural Color Materials
II-1. Introduction
Structural color is one of the interferences of light; itarises through the reflection of light from complexnanostructures found in the feathers of birds or the hardouter shell of beetles. These multi-layered structures
produce iridescence, whereby the color appears to change
depending on the angle of view. In contrast, Chladni
figures are one of the resonance phenomena of sounds; it

Figure 5. The optical textures in Chladni figures at thespecific vibrational frequencies.

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