# Permanent Deformation and Breakage Response of Recycled Concrete Aggregates under Cyclic Loading Subject to Moisture Change

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

_{pa}) was enhanced, and the breakage of coarse fraction (19~9.5 mm) under cyclic loading was reduced at higher levels of m.c. Based on the experimental results, a modified model for predicting ε

_{pa}was proposed, incorporating a deviation factor induced by m.c. The model fitted the experimental data well, suggesting that it is useful to have a quantitative estimation of ε

_{pa}of RCA with different m.c. under cyclic loading.

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Material

#### 2.2. Testing Methods

#### 2.2.1. Preparation of Samples

#### 2.2.2. Compaction Test

^{3}[22,23]. The sample was compacted using a two-way split mold and a rammer, and the specifications of compaction are shown in Table 1. Figure 3 depicts the measured compaction curve. The tested RCA specimen had a maximum dry density of 1.88 g/cm

^{3}and an optimal moisture content (OMC) of about 10%.

#### 2.2.3. Static and Cyclic Triaxial Tests

_{3}). Table 2 shows the summary of test conditions in this study. A function generator was used to convert electric signals through an EP transducer corresponding to the selected maximum and minimum deviatoric stresses (q). The stress states utilized in this study, i.e., axial, and confining stresses, were chosen based on the usual load sustained by pavements, as proposed by previous researchers [24]. To ensure constant contact between the load assembly and the specimen, constant contact stress (10% of the maximum deviatoric stress) was applied. Then, 4000 load cycles (N = 4000) were applied under constant confining pressure. The tested specimen was carefully retrieved after completing the desired number of loading cycles, then oven-dried and sieved to evaluate the particle breakage.

#### 2.2.4. Coloring Technique to Characterize Particle Breakage

## 3. Results and Discussion

#### 3.1. Particle Breakage after Compaction

_{g}) was adopted in this study [25,26]. The B

_{g}is a quantitative breakage index and is defined as the percentage by weight of the solid phase that has broken:

_{ki}is the percentage of the sample weight retained before the test in each sieve size and W

_{kf}is the percentage of the sample weight retained after the test in each sieve size. The calculated B

_{g}values are shown as a function of m.c. in Figure 7. It can be observed that the B

_{g}values decreased linearly with increasing m.c. This implies that direct and close contacts of particles enhanced the surface interparticle friction, resulting in more particle breakage due to the impact from particle to particle in drier conditions (lower m.c.). On the other hand, water between particles acts as a lubricant between them, and a cushion effect among particles lessened particle breakage more in a wetter condition (higher m.c.).

#### 3.2. Static Triaxial Test

_{3}= 40, 70, and 100 kPa) prior to evaluating the mechanical behavior of RCA specimens during cyclic loading. The test results are shown in Figure 9. With increasing σ

_{3}, the peak strength of the tested specimen increased and became approximately 1400 kPa at the deviation stress (q) of σ

_{3}= 100 kPa. The specimen failed after reaching over ε

_{a}= 3.5% for the tested conditions at σ

_{3}= 70 and 100 kPa. The tested specimen at σ

_{3}= 40 kPa, on the other hand, showed more strain resistance and reached failure at q = 600 kPa soon after ε

_{a}= 5%. The peak strength obtained from the static triaxial test was used to determine the maximum and minimum cyclic deviatoric stresses (σ

_{dmax}and σ

_{dmin}) for assessing the mechanical behavior of tested RCA during the cyclic triaxial tests.

_{v}) of investigated specimens first showed modest compression before becoming more dilative towards the end (Figure 9b). Aqil et al. [19] and Tatsuoka et al. [28] concluded that a compacted RCA specimen exhibited adequate strength in comparison to that of a graded gravelly soil. Kayani [29] reported that better inter-particle contacts between adjacent stiff aggregates increased the tangent stiffness and compressive strength. Further studies are needed to understand the effects of crushing a mortar layer surrounding the core particles and inter-particle contact points on the mechanical properties of RCA during triaxial compression loading.

#### 3.3. Cyclic Triaxial Test

_{dmax}and σ

_{dmin}) applied for the cyclic triaxial tests. The σ

_{dmax}was taken as about 65% of the maximum strength obtained in the static triaxial test [24], and 10% of the maximum deviatoric stress was taken as σ

_{dmin}to ensure constant contact between the loading rod, top cap, and tested specimen. The illustration in Figure 11 shows the explanation of strain development during cyclic loading. In this study, the permanent strain was calculated at the unloading stage of each designated loading cycle. According to a given number of loading cycles up to N = 4000, the accumulated permanent axial and volumetric strains (ε

_{pa}and ε

_{pv}) of the specimen were measured at three confining pressures (σ

_{3}) of 40, 70, and 100 kPa.

#### 3.3.1. Permanent and Volumetric Axial Strains

_{pa}and ε

_{pv}as a function of N at σ

_{3}= 40, 70, and 100 kPa are shown in Figure 12. Higher ε

_{pa}values (Figure 12a,b,e) were observed for the tested specimens with higher m.c. The ε

_{pa}-N curves, and therefore, the plastic response, tended to stabilize (plateau) with repeating N (at the end). In particular, the tested specimens with lower m.c. (5.4% and 6.9%) gave lower ε

_{pa}compared to the specimens with higher m.c. (9.5% and 11.56%). This behavior illustrates the state of RCA energy absorption in each stress–strain loop, as well as its ability to withstand minor permanent deformations at lower m.c. The stability of ε

_{pa}with the increasing number of loading cycles in an RCA sample shows that the plastic shakedown limit has been reached [30]. At lower m.c., the ε

_{pa}value of RCA sample suggests that the plastic limit has been reached.

_{pa}increased with m.c. under cyclic loading. This demonstrates that the tested RCA has a load-bearing capacity equivalent to a high-quality granular pavement material in accordance with other conventional pavement materials [31].

_{pv}-N relations were also dependent on the m.c. of tested RCA (Figure 12b,d,e). The ε

_{pv}of the specimen with m.c. = 11.6% (over OMC) showed generally dilative behavior under cyclic loading up to N = 4000. For the tested specimens with lower m.c. (5.4%, 6.9%, and 9.5%), on the other hand, the ε

_{pv}curves portrayed a compressive nature. The results might be attributed to the inter-particle contacts of aggregates at different m.c. conditions. For the specimen at higher m.c., it is supposed that the water escapes during drainage along with the settlement, increasing the interparticle contact and contributing to its dilative nature. For the specimen at lower m.c., on the other hand, the material matrix still has space for particle readjustment under cyclic loading, causing compressive behavior.

_{pa}, the measured ε

_{pa}values at N = 4000 were plotted as a function of m.c. and are shown in Figure 13. The ε

_{pa}increased nonlinearly with increasing m.c. at each σ

_{3}, and a large increment in ε

_{pa}can be found at an m.c. close to OMC (~10%). This suggests that the m.c. had a significant effect on the accumulation of permanent deformation under cyclic loading, consequently affecting the softening of RCA.

#### 3.3.2. Permanent Deformation Model

_{pa}= a(σ

_{d}/p

_{o}) bN

_{c}

_{pa}is the permanent axial strain, σ

_{d}is the axial deviatoric stress, p

_{o}is the normalizing stress (taken as 1 psi or 1 kPa), N is the number of loading cycles, and a, b, and c are model parameters obtained by a regression analysis of experimental data in this study. The PD model in Equation (4) was chosen because it incorporates the effect of applied stress compared to other predictive models [33], and the model can consider the effect of N regardless of the magnitude of loading.

_{w}) that incorporates the effect of the m.c. of tested specimens, as given in the following expression:

_{w}= me

^{αw}

_{pa}= a(σ

_{d}/p

_{o})

^{b}N

^{c}R

_{w}

_{w}in Equation (5) is shown in Figure 14. As shown in the figure, Equation (6) captured the effect of the m.c. of tested specimens in this study well, and the values of regression parameters, m and α, became 0.28 and 0.16, respectively. The performance of the modified PD model in Equation (6) was compared to experimental data. The prediction of existing model equation and its comparison with the modified equation is shown in Figure 15. The capability of the existing model is to predict similar trends at all moisture contents. However, the modified PD model showed reasonable agreement with the experimental data at different σ

_{3}conditions, suggesting it would be useful to have a quantitative estimation of the ε

_{pa}of RCA with different m.c. values under cyclic loading. Conversely, further research is recommended to verify the applicability of the modified equation due to the considerable variability of recycled and natural materials.

#### 3.3.3. Particle Breakage after Cyclic Loading

_{g}values (Equation (1)) after cyclic loading tests are shown as a function of m.c. in Figure 16. In the figure, a linear regression of the B

_{g-}m.c. relationship at the compaction stage of sample preparation is also given. It can be observed that the B

_{g}values decreased with increasing σ

_{3}and that the B

_{g}values became higher at lower m.c., compared to those at higher m.c. at > 9.5% (close to OMC = 10%). The results seem to be in accordance with a previous study by [34]. The study indicated that the elevated σ

_{3}decreased/weakened particle breakage and that less particle breakage (degradation) existed at the optimum degradation zone. As well as the tested results of particle breakage from compaction tests (Figure 7), the existing moisture is assumed to have created a cushion effect and/or a sliding surface surrounding the particles, resulting in small particle breakage of the tested RCA. Comparing the B

_{g}values after cyclic loading to those at the compaction stage, it is interesting that there was no significant difference between the tested specimens with m.c. = 5.4% and 6.9% at σ

_{3}= 100 kPa. This means no further particle breakage occurred during cyclic loading. The difference, on the other hand, became large for the specimen tested at σ

_{3}= 40 kPa throughout the whole m.c. range, indicating that particle breakage was enhanced during cyclic loading.

_{3}(Figure 17a–c). The effect of m.c. on particle breakage of coarse fractions was not clearly shown. The mass accumulation of the finer fraction of 2.36~0.075 mm, on the other hand, increased by approximately 10~20% (Figure 17d) and did not show any significant dependence on m.c.

## 4. Conclusions

- (1)
- The compaction moisture content has a significant effect on particle breakage. The results of both Marsal’s breakage ratio and mass reduction/accumulation showed that the particle breakage of RCA decreased with increasing moisture content.
- (2)
- The coloring technique introduced in this study showed that a coarse fraction of 9.5~4.75 mm was more breakable than the other fractions, mainly resulting in mass accumulations of fine fractions, suggesting a weak link in the particle size range, which needs to be adjusted.
- (3)
- The results from cyclic loading tests indicated that the moisture content of tested specimens had a considerable effect on the accumulation of permanent strain, and the increase in moisture content of tested specimens caused a decrease in stiffness, and consequently, an increase in permanent deformation in pavements.
- (4)
- Overall, the breakage and permanent deformation show opposite trends to each other.
- (5)
- Based on the experimental results, a model for evaluating a permanent axial strain was amended by newly incorporating it into a deviation factor induced by moisture content. The model fitted the experimental data well, suggesting that it would be useful to have a quantitative estimation of the permanent axial strain of RCA under cyclic loading.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

ε_{a} | Axial strain [%] |

σ_{3} | Confining pressure [kPa] |

σ_{d} | Deviatoric stress [kPa] |

σ_{dmax} | Maximum deviatoric stress [kPa] |

σ_{dmin} | Minimum deviatoric stress [kPa] |

ε_{pa} | Permanent axial strain [%] |

ε_{pv} | Permanent volumetric strain [%] |

ε_{v} | Volumetric strain [%] |

ΔW_{k} | Change in weight retained [g] |

W_{kf} | Final weight retained [g] |

W_{ki} | Initial weight retained [g] |

B_{r} | Marsal’s breakage index (no.) |

m.c. | Moisture content [%] |

p_{o} | Normalizing stress [kPa] |

N | Number of cycles (no.) |

PSD | Particle size distribution |

RCA | Recycled concrete aggregate |

## References

- Jayakody, S.; Gallage, C.; Kumar, A. Assessment of recycled concrete aggregates as a pavement material. Geomech. Eng.
**2014**, 6, 235–248. [Google Scholar] [CrossRef] [Green Version] - Cardoso, R.; Silva, R.V.; de Brito, J.; Dhir, R. Use of recycled aggregates from construction and demolition waste in geotechnical applications: A literature review. Waste Manag.
**2016**, 49, 131–145. [Google Scholar] [CrossRef] [PubMed] - Ouyang, K.; Shi, C.; Chu, H.; Guo, H.; Song, B.; Ding, Y.; Guan, X.; Zhu, J.; Zhang, H.; Wang, Y.; et al. An overview on the efficiency of different pretreatment techniques for recycled concrete aggregate. J. Clean. Prod.
**2016**, 263, 121264. [Google Scholar] [CrossRef] - Tawk, M.; Qi, Y.; Indraratna, B.; Rujikiatkamjorn, C.; Heitor, A. Behavior of a Mixture of Coal Wash and Rubber Crumbs under Cyclic Loading. J. Mater. Civ. Eng.
**2021**, 33, 21–54. [Google Scholar] [CrossRef] - Abukhettala, M. Use of recycled materials in road construction. In Proceedings of the 2nd International Conference on Civil, Structural and Transportation Engineering, ICCSTE’16, Ottawa, ON, Canada, 5–6 May 2016; p. 138. [Google Scholar]
- Teijón-López-Zuazo, E.; Vega-Zamanillo, Á.; Calzada-Pérez, M.Á.; Robles-Miguel, Á. Use of Recycled Aggregates Made from Construction and Demolition Waste in Sustainable Road Base Layers. Sustainability
**2020**, 12, 6663. [Google Scholar] [CrossRef] - Shi, C.; Li, Y.; Zhang, J.; Li, W.; Chong, L.; Xie, Z. Performance enhancement of recycled concrete aggregate–a review. J. Clean. Prod.
**2016**, 112, 466–472. [Google Scholar] [CrossRef] - Gu, F.; Zhang, Y.; Luo, X.; Sahin, H.; Lytton, R.L. Characterization and Prediction of Permanent Deformation Properties of Unbound Granular Materials for Pavement ME Design. Constr. Build. Mater.
**2017**, 155, 584–592. [Google Scholar] [CrossRef] [Green Version] - Alnedawi, A.; Rehman, M.A. Recycled Concrete Aggregate as Alternative Pavement Materials: Experimental and Parametric Study. J. Transp. Eng. Part B Pavements
**2021**, 147. [Google Scholar] [CrossRef] - Alnedawi, A.; Nepal, K.P.; Al-Ameri, R.; Alabdullah, M. Effect of vertical stress rest period on deformation behavior of unbound granular materials: Experimental and numerical investigations. J. Rock Mech. Geotech. Eng.
**2018**, 11, 172–180. [Google Scholar] [CrossRef] - Xiao, Y.; Zheng, K.; Chen, L.; Mao, J. Shakedown analysis of cyclic plastic deformation characteristics of unbound granular materials under moving wheel loads. Constr. Build. Mater.
**2018**, 167, 457–472. [Google Scholar] [CrossRef] - Piratheepan, J.; Gnanendran, C.T. Back-calculation of resilient modulus of lightly stabilized granular base materials from cyclic load testing facility. J. Mater. Civ. Eng.
**2012**, 25, 1068–1076. [Google Scholar] [CrossRef] - Sas, W.; Głuchowski, A.; Gabryś, K.; Soból, E.; Szymański, A. Deformation behavior of recycled concrete aggregate during cyclic and dynamic loading laboratory tests. Materials
**2016**, 9, 780. [Google Scholar] [CrossRef] [PubMed] [Green Version] - El-Ashwah, A.S.; Awed, A.M.; El-Badawy, S.M.; Gabr, A.R. A new approach for developing resilient modulus master surface to characterize granular pavement materials and subgrade soils. Constr. Build. Mater.
**2019**, 194, 372–385. [Google Scholar] [CrossRef] - Zeghal, M. The impact of grain crushing on road performance. Geotech. Geol. Eng.
**2009**, 27, 549–558. [Google Scholar] [CrossRef] [Green Version] - Arulrajah, A.; Piratheepan, J.; Ali MM, Y.; Bo, M.W. Geotechnical properties of recycled concrete aggregate in pavement sub-base applications. Geotech. Test. J.
**2012**, 35, 743–751. [Google Scholar] [CrossRef] - Arulrajah, A.; Piratheepan, J.; Disfani, M.M.; Bo, M.W. Geotechnical and geo-environmental properties of recycled construction and demolition materials in pavement subbase applications. J. Mater. Civ. Eng.
**2013**, 25, 1077–1088. [Google Scholar] [CrossRef] - Arulrajah, A.; Piratheepan, J.; Disfani, M.M. Reclaimed asphalt pavement and recycled concrete aggregate blends in pavement subbases: Laboratory and field evaluation. J. Mater. Civ. Eng.
**2014**, 26, 349–357. [Google Scholar] [CrossRef] - Aqil, U.; Tatsuoka, F.; Uchimura, T.; Lohani, T.N.; Tomita, Y.; Matsushima, K. Strength and deformation characteristics of recycled concrete aggregate as a backfill material. Soils Found.
**2005**, 45, 53–72. [Google Scholar] [CrossRef] [Green Version] - Gobieanandh, V.; Jayakody, S. Evaluate the strength of cement treated recycled construction and demolition aggregates as a pavement material. In Proceedings of the 7th International Conference on Sustainable Built Environment, Kandy, Sri Lanka, 16–18 December 2016. [Google Scholar]
- JRA-RM-30; Gradation Standard for Recycled Materials. Japan Road Association (JRA): Tokyo, Japan, 2010. (In Japanese)
- ASTM D 1557; Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort. American Society for Testing and Materials: West Conshohocken, PA, USA, 2007.
- JIS A 1210; Soil Compaction Test Method by Compaction: Test Method for Soil Compaction Using a Rammer. Japanese Standards Association: Tokyo, Japan, 2020. (In Japanese)
- Frost, M.W.; Fleming, P.R.; Rogers, C.D.F. Threshold stress and asymptotic stiffness of UK clays in the repeated load triaxial test. In Proceedings of the 6th International Conference on the Bearing Capacity of Roads and Airfields, Lisbon, Portugal, 24–26 June 2002; pp. 1099–1108. [Google Scholar]
- Marsal, R.J. Large scale testing of rockfill materials. J. Soil Mech. Found. Div. ASCE
**1967**, 93, 27–43. [Google Scholar] [CrossRef] - Tawk, M.; Indraratna, B.; Rujikiatkamjorn, C.; Heitor, A. Review on compaction and shearing induced breakage of granular material. Geotech. Transp. Infrastruct.
**2019**, 2, 259–270. [Google Scholar] - Sun, Y.; Nimbalkar, S.; Chen, C. Particle breakage of granular materials during sample preparation. J. Rock Mech. Geotech. Eng.
**2019**, 11, 417–422. [Google Scholar] [CrossRef] - Tatsuoka, F.; Tomita, Y.; Iguchi, Y.; Harikawa, D. Strength and stiffness of compacted crushed concrete aggregate. Soils Found.
**2013**, 53, 835–852. [Google Scholar] [CrossRef] [Green Version] - Kayani, J.Q. Feasibility for Use of Recycled Graded Concrete Aggregate and Crushed Autoclaved Lightweight Concrete (ALC) in Permeable Pavement System. Master’s Thesis, Saitama University, Saitama, Japan, 2018. [Google Scholar]
- Cerni, G.; Cardone, F.; Virgili, A.; Camilli, S. Characterization of permanent deformation behavior of unbound granular materials under repeated triaxial loading. Constr. Build. Mater.
**2012**, 28, 79–87. [Google Scholar] [CrossRef] - Lekarp, F.; Richardson, I.R.; Dawson, A. Influences on permanent deformation behavior of unbound granular materials. Transp. Res. Record.
**1996**, 1547, 68–75. [Google Scholar] [CrossRef] - Ullidtz, P. Modelling of granular materials using discrete element method. In Proceedings of the 8th International Conference on Asphalt Pavements, Seattle, WA, USA, 10–14 August 1997; pp. 757–769. [Google Scholar]
- Tutumluer, E. NCHRP Synthesis of Highway Practice 445: Practices for Unbound in Aggregate Pavement Layers; Transportation Research Board of the National Academies: Washington, DC, USA, 2013. [Google Scholar]
- Indraratna, B.; Lackenby, J.; Christie, D. Effect of confining pressure on the degradation of ballast under cyclic loading. Geotechnique
**2005**, 55, 325–328. [Google Scholar] [CrossRef]

**Figure 2.**Particle size distribution (PSD) of tested sample in this study. The upper and lower boundaries are indicated by dotted lines.

**Figure 5.**Flow diagram of laboratory test consisting of coloring of aggregates, grading, compaction, static/cyclic loading, and particle tracking after test.

**Figure 6.**Particle size distribution curves before and after compaction at m.c. = 15% and m.c. = 5.4%.

**Figure 8.**(

**a**) Mass reduction of coarse aggregate fraction; (

**b**) mass accumulation of fine fraction measured by particle tracking using coloring technique.

**Figure 12.**Permanent axial and volumetric strains (ε

_{pa}and ε

_{pv}) as a function of N: (

**a**,

**b**) σ

_{3}= 40 kPa, (

**c**,

**d**) σ

_{3}= 70 kPa, and (

**e**,

**f**) σ

_{3}= 100 kPa.

**Figure 15.**Comparison between the estimation of modified permanent deformation (PD) model [Equation (6)] (dotted lines) and experimental data (solid lines except the green colored) for tested specimen: (

**a**) σ

_{3}= 40 kPa, (

**b**) σ

_{3}= 70 kPa, and (

**c**) σ

_{3}= 100 kPa.

**Figure 16.**Marsal’s breakage index (B

_{g}) as a function of moisture content (m.c.) after compaction and cyclic loading at N = 4000.

**Figure 17.**Mass reduction of coarse fraction: (

**a**) σ

_{3}= 40 kPa, (

**b**) σ

_{3}= 70 kPa, and (

**c**) σ

_{3}= 100 kPa. (

**d**) Mass accumulation of fine fraction at σ

_{3}= 40, 70 and 70 kPa.

Mold | Rammer | ||
---|---|---|---|

Height (cm) | 15 | Drop height (cm) | 45 |

Diameter (cm) | 7.5 | Weight (kg) | 4.5 |

Test Conditions | |
---|---|

Compaction energy [kJ/m^{3}] | 2700 |

Moisture content [%] | 5.4, 6.9, 9.5, 11.56, 15 (15% for compaction only) |

Frequency [Hz] | 0.2 |

Number of cycles [Nos.] | 4000 |

Confining pressure [kPa] | 40, 70, 100 |

Max. cyclic deviatoric stress [kPa] | 450, 580, 850 |

Min. cyclic deviatoric stress [kPa] | 45, 58, 85 |

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Shah, S.K.H.; Uchimura, T.; Kawamoto, K.
Permanent Deformation and Breakage Response of Recycled Concrete Aggregates under Cyclic Loading Subject to Moisture Change. *Sustainability* **2022**, *14*, 5427.
https://doi.org/10.3390/su14095427

**AMA Style**

Shah SKH, Uchimura T, Kawamoto K.
Permanent Deformation and Breakage Response of Recycled Concrete Aggregates under Cyclic Loading Subject to Moisture Change. *Sustainability*. 2022; 14(9):5427.
https://doi.org/10.3390/su14095427

**Chicago/Turabian Style**

Shah, Syed Kamran Hussain, Taro Uchimura, and Ken Kawamoto.
2022. "Permanent Deformation and Breakage Response of Recycled Concrete Aggregates under Cyclic Loading Subject to Moisture Change" *Sustainability* 14, no. 9: 5427.
https://doi.org/10.3390/su14095427