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Guarin, Alvaro
Publications (4 of 4) Show all publications
Sun, G., Sun, D., Guarin, A., Ma, J., Chen, F. & Ghafooriroozbahany, E. (2019). Low temperature self-healing character of asphalt mixtures under different fatigue damage degrees. Construction and Building Materials, 223, 870-882
Open this publication in new window or tab >>Low temperature self-healing character of asphalt mixtures under different fatigue damage degrees
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2019 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 223, p. 870-882Article in journal (Refereed) Published
Abstract [en]

The primary objective of this study is to advance the understanding of the low temperature self-healing character of asphalt mixtures under different damage degrees, thus to determine the effective strategy of asphalt pavement maintenance. Firstly, three kinds of asphalt mixtures are selected to conduct the indirect tensile (IDT) fatigue test to a certain fatigue damage degree at low temperatures, and then the resilient modulus (Mr) at different rest time is measured to quantify the healing potential. Next, the fatigue loading with different intermittent time (0 s, 1 s and 3 s) is applied to determine the impact of intermittent time on healing potential. The results indicate that the descending order of healing potential of asphalt mixtures is: SMA-11 > AC-8 > AC-11 at 5 degrees C and -5 degrees C. The loading intermittent time has an obvious effect on the fatigue damage state of asphalt mixtures, while the longer the intermittent time, the less the effect on fatigue damage healing. Besides, the fatigue damage state has great influence on its healing potential of asphalt mixture. Under the low damage conditions, the initial healing rate is greater than the long term healing rate. However, the low temperature (-5 degrees C) dramatically reduces the healing rate of asphalt mixtures, and causes their long-term healing rate to stabilize gradually to a very low level. Especially under the high fatigue damage conditions, the healing potential of asphalt mixtures will almost disappear at -5 degrees C. Furthermore, together with meso-scale Computed Tomography (CT) scanning technique, it is found that the intemal crack distribution characteristics of different graded asphalt mixtures are different even under the same damage degree, which may explain the differences in the healing potential of asphalt mixtures. The use of a fast two-dimensional (2D) scanning technology further confirms that the crack zones inside the asphalt mixture are gradually shrinking after a period of high temperature healing. Finally, the Grey relational analysis reveals that the healing time has the most significant influence on the healing potential of asphalt mixtures. The gradation type and temperature have the similar influence level on the healing potential. The correlation degree between the fatigue damage degree and healing potential is the smallest compared with the other three factors. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Indirect tensile (IDT) fatigue, Damage degree, Healing potential, Computed Tomography (CT), Asphalt mixtures
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-262769 (URN)10.1016/j.conbuildmat.2019.07.040 (DOI)000487569100075 ()2-s2.0-85068884490 (Scopus ID)
Note

QC 20191022

Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2019-11-26Bibliographically approved
Ahmed, L. & Guarin, A. (2018). Crack propagation under water pressure. Stockholm/Sweden
Open this publication in new window or tab >>Crack propagation under water pressure
2018 (English)Report (Refereed)
Abstract [en]

Cracks in concrete structures such as a concrete dam can be exposed to water pressure, for example, uplift pressure. The water pressure can be significant and may result in cracks propagating through the structures and thus it may result in reduced service life. However, the knowledge of water pressure within the cracks is relatively limited and is often neglected or just roughly estimated. The influence of crack opening rate on the uplift pressure distribution in the crack and the pressure variation during opening or sudden crack closure are questions needed to investigate. As an attempt to answer those questions, a pilot study presented here describes the possibilities and limitations of the proposed experimental setup; and technology (penetrability meter and tomography) as an examination method for water pressure in propagation concrete cracks. The test specimens examined here are exclusively cylinders cast of concrete with or without an initial crack.

The penetrability meter can be used to apply water pressure and to visualize the crack opening, X-Ray computed tomography test, was performed. KTH Civil and Architectural Engineering department has organized the laboratory resources.

The examples reported in this work show that the technology and equipment have great potential for future work on crack propagation, however, sample design and preparation, as well as testing need further development.

Place, publisher, year, edition, pages
Stockholm/Sweden: , 2018
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-235263 (URN)
Note

QC 20180920

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-20Bibliographically approved
Ghafoori Roozbahany, E., Partl, M. & Guarin, A. (2018). Influence of layer thickness on the flow of asphalt under simulated compaction. In: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017: . Paper presented at 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, 28 June 2017 through 30 June 2017 (pp. 1435-1441). CRC Press/Balkema
Open this publication in new window or tab >>Influence of layer thickness on the flow of asphalt under simulated compaction
2018 (English)In: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, CRC Press/Balkema , 2018, p. 1435-1441Conference paper, Published paper (Refereed)
Abstract [en]

Compaction is one of the most important phases in the life cycle of asphalt pavements and has therefore been a hot subject of research for a long time. However, despite of valuable research efforts on this topic, a remarkable gap between laboratory and field measurements still remains. Moreover, whereas most of the experimental methods are carried out on compacted pavement material, methods for evaluating compactability of asphalt mixtures for increasing the fundamental knowledge about internal movements within the asphalt during compaction are only scarce. Hence, in this study, a recently developed tool for simulating the compaction process with respect to the particle flow, i.e. Compaction Flow Test (CFT), was used along with simultaneous X-ray imaging for investigating the impact of thickness changes on two different asphalt mixture structures in terms of the compaction effort as well as flow pattern differences. The results of the investigation provided reasonably useful input for building up a better understanding of the behavior of mixtures under compaction loads. This method was able to successfully reveal the differences of the structural rearrangements within the asphalt mixtures for three different lift thicknesses. It also helped to explain some of the previous research studies results in a more comprehensive way. The achievements of this study may serve for developing an in-site evaluating test method for assessing compactability of asphalt mixtures before placing them on the roads.

Place, publisher, year, edition, pages
CRC Press/Balkema, 2018
Keywords
Compactability, Lift thickness, Particle flow, X-ray computed tomography, Bearing capacity, Compaction, Computerized tomography, Flow patterns, Life cycle, Mixtures, Railroads, Compaction effort, Compaction process, Experimental methods, Field measurement, Structural rearrangement, Asphalt mixtures
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-247234 (URN)10.1201/9781315100333-205 (DOI)2-s2.0-85058531077 (Scopus ID)9781138295957 (ISBN)
Conference
10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, 28 June 2017 through 30 June 2017
Note

QC 20190402

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-02Bibliographically approved
Ansell, A., Ahmed, L. & Guarin, A. (2017). Computed tomography as investigation method for steel fibre reinforced tunnel shotcrete. In: : . Paper presented at XXIII Symposium on Nordic Concrete Research & Development, Aalborg (pp. 63-66).
Open this publication in new window or tab >>Computed tomography as investigation method for steel fibre reinforced tunnel shotcrete
2017 (English)Conference paper, Published paper (Refereed)
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-235252 (URN)
Conference
XXIII Symposium on Nordic Concrete Research & Development, Aalborg
Note

QC 20180920

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-20Bibliographically approved
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