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Proceedings of Engineering and Technology Innovation , vol. 3, 2016, pp. 31 - 33 

31 

Experimental Study of the Crack Control of Concrete by 

Self-healing of Synthetic Fiber Reinforced Cementitious 

Composites Synthetic Fiber 

Heesup Choi 
1,*

, Masumi Inoue 
1
, Takechi Ai 

1
, Tomoya Nishiwaki

2
, 

Myungkwan Lim 
3
, Hyeonggil Choi 

4
 

1
Department of Civil Engineering, Kitami Institute of Technology, Hokkaido, Japan . 

2
Department of Architecture and Building Science, Tohoku University, Sendai, Japan . 

3
Graduated School of Engineering, Hankyong National University, Kyonggido, Korea . 

4
Faculty of Environmental Technology, Muroran Institute of Technology, Hokkaido, Japan . 

Received 25 January 2016; received in revised form 10 February 2016; accept ed 06 March 2016 

 

Abstract 

In this study, it is possible to disperse effec -

tively cracked using synthetic fiber, an e xa mi-

nation of the most suitable self-healing condi-

tions was performed on the above crack width 

0.1mm. As a result, e ffective c rack dispersion 

using polyvinyl alcohol (PVA ) fibers with pola r 

OH
-
 groups, as well as improved self-healing for 

cracks that are la rger than 0.1 mm in width, 

posing concerns of CO2 gas and Cl
-
 penetration, 

were  observed. Also, CO3
2-

 reacts with Ca
2+

 in  

the concrete crack, resulting in the precipitation 

of a  carbonate compound, CaCO3. Based on this, 

it is deemed possible for the recovery of effec -

tive watertightness to be made fro m c racks that 

are la rger than 0.1 mm in width. In addition, it  

was determined that, as for the most suitable 

self-healing conditions in the inside and surface  

of the cracks, calciu m hydro xide (Ca(OH)2) 

solution with CO2 mic ro-bubble was more  ef-

fective in pro moting the self-healing capability  

than water with CO2 micro-bubble. 

Keywor ds : micro crack, PVA, CO2 mi-

cro-bubble, s elf-healing,Ca(OH)2, 

CaCO3 

1. Introduction 

Although concrete is one of the most widely  

used construction materials, it is characterized  

by substantially low tensile strength in compar-

ison to its compression strength, and occurrence 

of cracks is unavoidable. In addition, cracks  

progress due to environmen tal conditions in-

cluding da mage by freezing, neutralization and  

salt damage, etc. Moreover, detrimental da m-

ages can occur in concrete structures due to the 

permeat ion of deteriorat ing ele ments such as Cl
-
 

and CO2, etc. Meanwh ile, under an environment  

in wh ich moisture is being supplied, if the width 

of the crac k is sma ll, a  phenomenon of 

self-healing in which the portion of the crack is 

filled in due to the rehydration of the ce ment  

particles and precip itation of CaCO3 has been 

confirmed. As for the self-healing mechanis m of 

concrete, the reaction between Ca
2+

 in concrete 

and CO3
2-

 dissolved in water produces CaCO3, a  

carbonate compound that does not easily dis-

solve in water. This phenomenon leads to the 

filling and c losing of crac ks [1]. The  calc ite  

crystal reactions are shown in Equations [1-3] 

H2O + CO2⇔H2CO3 

⇔H
+
+ HCO3-⇔2H

+ 
+ CO3

2-
 

(1) 

Ca
2+ 

+ CO3
2- 

⇔ CaCO3 {pHwater＞ 8} 
(2) 

Ca
2+ 

+ HCO3
-
⇔ 

CaCO3 + H
+
 {7.5 ＜pHwater＜8} 

(3) 

Therefore, this study effectively disperses 

the cracks in the cracks in the ce mentitious 

composite materia ls by using synthetic fiber, 

and, for the cracks with a width of more  than 

0.1mm, e xecuted the review of the optima l 

* Corresponding aut hor. Email: hs-choi@mail.kitami-it.ac.jp 



Proceedings of Engineering and Technology Innovation , vol. 3, 2016, pp. 31 - 33 

32 Copyright ©  TAETI 

self-healing conditions along with the revie w of 

a diverse range of self-healing performance. 

2. Experimental Overview 

The mixture  proportions of the mo rtar a re  

summarized in Table 1. Portland ce ment (C, 

density: 3.16 g/c m
3
, mean d ia meter: 10 μ m), 

quartz sand as the fine aggregate (S, surface-dry  

density: 2.61 g/cm
3
, mean dia meter: 180 μ m), 

and a high-performance water reducing agent as 

an admixture (SP, density: 1.05 g/cm
3
, ma in  

constituent: polycarboxylate-based superplasti-

cizer) we re used. As for the synthetic fibers, 

PVA (fiber dia meter: 40 μ m, fiber length: 12 

mm, density: 1.3 g/c m
3
) and polyethylene (PE) 

(fiber dia mete r: 12 μ m, fiber length: 12 mm, 

density: 0.97 g/c m
3
) and polypropylene (PP) 

(fiber dia mete r: 65 μ m, fiber length: 12 mm, 

density: 0.91 g/cm
3
) were used. 

Table 1Mixture proportions of the mortar 

Type 
S/C 

(Wt.%) 

W/C 

(Wt.%) 

SP/C 

(Wt.%) 

Fiber 

(vol.%) 

PVA 

0.4 0.3 

0.4 

1.2 PE 0.45 

PP 0.3 

Table 2 Experimental factors and conditions  

Experimental factors  Conditions  

Fiber PVA, PE, PP 

Self- 

healing 

Water + Mi-

cro-bubble 
pH 6.0 

Ca(OH)2 + Mi-

cro-bubble 
pH 8.5 

Temperature 20°C 

Crack (Target of crack 

width: 0.3mm) 
Tensile load 

Period of self-healing 7 Days  

As the Experimental procedure, in ST EP A, 

an analysis of the permeability coeffic ient i m-

med iately following the introduction of the 

cracks by the tensile loading test (prior to  

self-healing), and an  analysis of the types of the 

hydrates prior to self-healing by using the Ra-

man spectroscopy were executed. In ST EP B, a  

comparison and evaluation were made by using 

the method applied in ST EP A in order to eva l-

uate the changes in the permeability of each of 

the specimens due to self-healing, changes in the 

structure within  the cracks and a quantitative 

evaluation the self-healing precip itated sub-

stances. The experimental factors and conditions 

are summarized in Table 2. 

3. Results and Discussion 

3.1. Permeability Coefficient 

As the results of the experiment, W+M B in  

ST EP B, when compared with that in ST EP A, 

displayed the trend of an increase in  the re -

sistance to permeability by about 40 fo lds for 

PVA, 3.5 fo lds for PE and 1.5 folds for PP(Fig  1). 

Meanwhile, Ca +MB in ST EP B, when co m-

pared with that in ST EP A, displayed the trend 

of an increase in  the resistance to permeability  

by about 460 folds for PVA , 60 fo lds for PE and  

6.0 folds for PP (Fig 2). In addition, in the com-

parison of the permeability coeffic ient follo wing  

self-healing, Ca+M B, in co mparison to W+MB, 

displayed the trend of improve ment in the re -

sistance to permeability by appro ximately 15 

folds for PVA, 17 fo lds for PE and 4.0 fo lds for 

PP (Fig 3). Fro m the afore mentioned results, it  

can be discerned that the resistance to permea -

bility is improved in the order of PVA>PE>PP, 

regardless of the conditions of self-healing. In  

particular, PVA with OH-radica l d isplays a 

more e ffective self-healing performance [2], and, 

it was confirmed that the conditions of Ca+M B 

are more advantageous than the conditions of 

W+MB for the pro motion of self-hea ling per-

formance. Therefore , for the micro crac ks with a  

width of mo re than 0.1mm for wh ich substantial 

permeat ion of deteriorating  ele ments fro m the  

e xternal into the internal aspects of the concrete 

is anticipated, it is deemed that the generation 

and precipitation of the self -healing substances 

were pro moted due to the mixing of the PVA  

fiber with the OH
-
 radica l a long with the intro-

duction of the conditions of self -healing  of the  

saturated Ca(OH)2 solution (Ca
2+

) that contains 

CO2 micro bubbles (CO3
2-

). 

3.2. Review of the Crack  Section Due to 

Self-healing 

Fig  4 shows  the e xperimental results of 
Ra man spectroscopy. Here, the locations of the 

occurrence of the peak of a wave generated by a 

laser at the crack section to which the white  

colored precipitated substance of PVA specimen  

is attached and that at the sectio ns without 

cracks were co mpared. As the results of the 

e xperiment, with the peak of the wave of Ca -

CO3powder as the subject of comparison, there 

was almost no occurrence of the peak in the 



Proceedings of Engineering and Technology Innovation , vol. 3, 2016, pp. 31 - 33 

33 Copyright ©  TAETI 

wave of the sections without cracks that coin-

cides with that of the CaCO3. Ho wever, the peak 

of the wave in the c rack section accurately co-

incides with the peak of the wave of Ca CO3  

powder. Accordingly, it is concluded that the 

ma jority of the white colored precipitated sub-

stance was generated following self -healing due 

to CaCO3. 

 
Fig. 1 Permeab ility coeffic ient of Water + Micro  

bubble (W + MB). 

 
Fig. 2 Permeability coeffic ient of Ca (OH)2 + 

Micro-bubble (Ca + MB). 

 
Fig. 3 Co mparison of permeability coefficient  

ratio 

 
Fig. 4 Precipitated substances of self-healing 

4. Conclusions 

In this paper, it was confirmed that the ef-

fective restoration of water t ightness and the 

ma jority of the self-hea ling products was due to 

Ca CO3 by using synthetic fiber with polarity, 

along with the effect of inducing a multip le  

number of hairline cracks. In addition, it was 

confirmed that the self-healing conditions of the 

saturated Ca(OH)2 solution, wh ich supplied the 

CO2 micro-bubble, displayed the most effective 

self-healing performance  in the surface and  

internal sections of the cracks. 

Acknowledgement 

This work was supported by the young re-

searcher program of LIXIL 2015. 

References 

[1] C. Edvardsen, “Water permeability and 
autogenous  healing of c racks in concrete,”  

ACI Materials Journal, vol. 96, no. 4, pp. 

448-454, 1999. 

[2] D. Ho mma , H. M ihashi, and T. Nishiwa ki, 
“Self-healing capability of fiber re inforced  

cementit ious  composites ,” Journal of Ad-

vanced Concrete Technology, vol. 7, no. 2, 

pp. 217-228, 2009. 

0.0000001

0.000001

0.00001

0.0001

0.001

0.01

0.1

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PVA PE PP

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1 = Standard 

0

5

10

15

20

25

0 500 1000 1500 2000

In
te

n
s
it

y
 (
c
o

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n

ts
)

Raman shift/cm-1

0

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Crack

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p owder