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

A Fundamental Study on the Effect of Pigment Use Amounton the Color of Colored Mortar- Method of Setting the Pigment Substitution Rate for Cement Hiroshi JinnaiTokyo Polytechnic Univ., 1583 Iiyama, Atsugi, Kanagawa 243-0297, JapanAs an example, Fig. 2 and Fig. 3 show figures from theexamination of the effects of the pigment substitution rate
and the lapse of time on the L*a*b* values based on theexperimental data obtained in the previous study. Figure 2shows the results of examination of mortar with the waterbinder ratio of 0.5, and Fig. 3 shows the results ofexamination of mortar with the water binder ratio of 0.2. As
can be seen from these figures, the relation between thepigment substitution rate and the L*a*b* values changes
over time. The timing at which these changes ceaseoccurring depends on the mixture design of the mortar. In
this study's experiment, it was thought that if the pigment
substitution rate is set based on the measurement data for
about one month, it will be possible to design colored
concrete that retains almost the same L*a*b* values evenafter two years. Lastly, the mixture design of the colored
concrete is performed so as to achieve the pigment
substitution rate determined as described. This design
method prevents defects such as deviation of color of thecolored concrete from the target color over time.

ABSTRACTIn the previous study, the author measured the change
in color of colored mortars with different amounts ofpigments over time. As a result, it was found that in themixture design of colored mortars, considering color
change over time is as important as setting the pigment
use amount. Therefore, in this study, a method to set thepigment substitution rate for cement based on themeasured color values of mortar was investigated.
1. INTRODUCTION
The color of concrete is considered to be largely
determined by the color of the cement, water and fineaggregate at the surface of the concrete. Therefore, todetermine the color of concrete, it is sufficient to determine
the color of the mortar, which is the concrete minus thecoarse aggregate.
The color of mortar is considered to be largely
determined by the color of the cement paste, which
consists of cement and water. Further, the color of the fineaggregate near the surface layer of the mortar also slightly
affects the color of the mortar. Therefore, in the previous
study, the author fabricated a white mortar using white
cement and fine aggregate, and also fabricated a coloredmortar in which some of the cement of the mortar wasreplaced with pigment, to experimentally verify the effectof the pigment substitution rate and other factors on thecolor of the mortar surface layer. The results of thisexperiment confirmed that the production of coloredmortar (concrete) of the desired color requires not only
setting of the pigment use amount, but also considerationof the change in color of the mortar over time. The change
in the color of mortar over time was confirmed to be due toevaporation of the water in the mortar over time.
Therefore, in this study, a method to set the pigment
substitution rate for cement based on the measured color
values of mortar was investigated.

Start
Set the target color of the colored concrete
Measure the L*a*b* values of the colored mortar(Check the effect of the pigment substitution rateand lapse of time on the L*a*b* values)

Set the pigment substitution rate in considerationof the change in color over time
Determine the mixture proportion of
the colored concrete in consideration of
the pigment substitution rate

2. Proposed flow of colored concrete mixture design
The proposed flow of colored concrete mixture design isshown in Fig. 1. First, the target color of the colored
concrete is set. Next, an experiment to measure the L*a*b*
values of the colored mortar is performed. In thisexperiment, the effects of the pigment substitution rate
and the lapse of time on the L*a*b* values is investigated.

Fig.1 Design flow of colored mortar (concrete)

27

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

10090807060
50
40
30
20
100

W/B=0.5：1days
024

W/B=0.5：2days
60ａ*

Pigment substitution rate(%)

50
40
30
20
100-10-20-30-40-50
240224Green

24

602
Blue4(1days)

Green

60

20

2

60

202

46(2days)Green402024

6

W/B=0.5：2years

W/B=0.5：1years
64

Pigment substitution rate(%)

60246Pigment substitution rate(%)

W/B=0.5：29days

W/B=0.5：1years

W/B=0.5：2years

2Blue(7days)

W/B=0.5：2years
6

Pigment substitution rate(%)

460

Pigment substitution rate(%)

Yellow

42

Pigment substitution rate(%)

0

Pigment substitution rate(%)

Blue

0

Pigment substitution rate(%)

W/B=0.5：7days

6

W/B=0.5：1years
6

W/B=0.5：29days

4

Pigment substitution rate(%)

Yellow

4

Pigment substitution rate(%)

W/B=0.5：7days
6

Pigment substitution rate(%)

Yellow

W/B=0.5：29days

4

Pigment substitution rate(%)

W/B=0.5：2days

Pigment substitution rate(%)

Blue

0

Pigment substitution rate(%)

W/B=0.5：1days

0W/B=0.5：7days
6W/B=0.5：2days
6Pigment substitution rate(%)

60
5040
3020
100-10-20-30-40

4Pigment substitution rate(%)

W/B=0.5：1days
0ｂ*2

Green

4260Blue(29days)

Green

246

Pigment substitution rate(%)

Pigment substitution rate(%)

Yellow

YellowBlue(1years)

Green

Yellow(2years)L*

Fig.2 Relation between pigment substitution rate and L*a*b* value (W/B=0.5：Flat plate specimens)
10090807060504030
20100

W/B=0.2：1days
0240ａ*

Pigment substitution rate(%)

50403020100-10-20-30-40-502460
50403020100-10-20-30-40
24Green(1days)

0202460Pigment substitution rate(%)

Yellow

024Green(2days)

022

Yellow

02646Pigment substitution rate(%)

BlueGreen

60202

Yellow(7days)

44

W/B=0.2：2years
60Pigment substitution rate(%)

2602446Pigment substitution rate(%)

W/B=0.2：1years

W/B=0.2：29days4

W/B=0.2：2years
602

4

6

Pigment substitution rate(%)

Pigment substitution rate(%)

Pigment substitution rate(%)

W/B=0.2：29days

W/B=0.2：1years

W/B=0.2：2years

W/B=0.2：7days

64

Pigment substitution rate(%)

Pigment substitution rate(%)

Pigment substitution rate(%)

Blue

6

W/B=0.2：7days
6

W/B=0.2：1years

W/B=0.2：29days

4

Pigment substitution rate(%)

W/B=0.2：2days

Pigment substitution rate(%)

Blue

6

W/B=0.2：2days
6

W/B=0.2：1days

04

Pigment substitution rate(%)

Pigment substitution rate(%)

ｂ*2

W/B=0.2：1days
0W/B=0.2：7days

W/B=0.2：2days
60246Pigment substitution rate(%)

BlueGreen(29days)

Yellow

0246

Pigment substitution rate(%)

Blue

Green

Yellow(1years)

0246

Pigment substitution rate(%)

Blue

Green

Yellow(2years)

Fig.3 Relation between pigment substitution rate and L*a*b* value (W/B=0.2：Flat plate specimens)

proposed. This design method is thought to prevent
defects such as deviation of color of colored concrete fromthe target color over time.

3. CONCLUSION
Based on the experimental data from the previous study,
a flow for the mixture design of colored concrete is28