Autogenous healing of engineered cementitious composites under wet–dry cycles

Yang, Yutao; Lepech, Michael D.; Yang, En-Hua; Li, Victor C.

doi:10.1016/j.cemconres.2009.01.013

Cited by 575 publications

(308 citation statements)

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“…For concrete of sufficient age, the formation of calcium carbonate primarily occurs (e.g. Jacobsen and Sellevold 1996;Hearn and Morley 1997;Hearn 1997;Edvardsen 1999;Van der Zwaag 2007;Homma et al 2009;Qian et al 2009;Yang et al 2009). While Heap et al (2013) showed that the water permeability of concrete increases significantly with the progress of fracturing, it is also possible that the sealing of existing fractures and pores affects the permeability of concrete.…”

Section: Introductionmentioning

confidence: 99%

“…While Heap et al (2013) showed that the water permeability of concrete increases significantly with the progress of fracturing, it is also possible that the sealing of existing fractures and pores affects the permeability of concrete. So far, various reports on the fracture sealing of concrete have been published (e.g., Jacobsen and Sellevold 1996;Hearn and Morley 1997;Hearn 1997;Edvardsen 1999;Reinhardt and Jooss 2003;Granger et al 2007; Van der Zwaag 2007;Homma et al 2009;Qian et al 2009;Yang et al 2009;Ahn and Kishi 2010;Wu et al 2012;Fukuda et al 2012;Fukuda et al 2013). Among this literature, Edvardsen (1999) showed that the sealing of a fracture occurs by the precipitation of calcium carbonate, generated from CO 3 2− in the water and Ca 2+ in the cement paste, and that the fracture aperture and applied water pressure significantly affect the sealing, while the types of cement and aggregate and the hardness of the water have no influence on the sealing rate.…”

Section: Introductionmentioning

confidence: 99%

“…Reinhardt and Jooss (2003) showed that fracture sealing is significantly influenced by temperature up to 80 °C, resulting in a decrease in water transport, i.e., more significant sealing with increasing temperature. It 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 has been shown that sealing in engineered cementitious composites in water occurs if the fracture aperture is less than 0.15 mm (Yang et al 2009), while sealing in HSULPC kept in simulated seawater up to 49 days occurred when the fracture aperture was 0.1 mm but not 0.25 mm (Fukuda et al 2012;Fukuda et al 2013). Thus, it seems that not only the composition of cementitious composites and cementitious materials and its spatial distribution but also the surrounding environment affect sealing behavior.…”

Section: Introductionmentioning

confidence: 99%

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Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

et al. 2014

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Fracture sealing by precipitation is known to occur in high-strength and ultra-lowpermeability concrete (HSULPC) immersed in water. Because a high ability to retard radionuclide migration is required for HSULPC, understanding both the sealing process and the composition of sealing deposits is important to identify optimum conditions for significant sealing. In this study, sealing of a macro-fractured HSULPC specimen with initial aperture of approximately 0.1 mm was investigated in simulated seawater over 49 days. The composition of sealing deposits at 49 days after immersion was clarified by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), and the progress of sealing during the 49 days was clarified by image analysis with micro-focus X-ray computed tomography (X-rayCT). Both the SEM/EDX and X-rayCT results showed that significant sealing was attained only near the outermost part of the specimen. The SEM/EDX results showed that a thin brucite layer formed on the entire specimen surface over which significant precipitation of calcium carbonate occurred and sealed the macro-fracture only near the outermost part of the specimen. The X-rayCT results indicated that the amount of sealing deposits in the macro-fracture (P seal ) reached 70 % in the mostly sealed region at 49 days and the rate of change in P seal became maximum (3.7 % day -1 ) during 7-21 days after immersion, then decreased. In conclusion, Revised_Manuscript Click here to download Manuscript: IJF_manuscript_FRAC_Rev1.doc Click here to view linked References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 the findings in this study represent an important clue in the search for optimum conditions to achieve fracture sealing in HSUPLC.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

et al. 2014

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“…3). Complete sealing is assumed to take place when concrete cracks are limited to below 30 μm, as has been experimentally demonstrated (Yang et al 2009). This results in a lowering of the chloride diffusion coefficient that forms the input to Life-365 that computes the lengthened service life and reduction in life cycle cost.…”

Section: Impact Of Self-healing On Infrastructure Life Cycle Costmentioning

confidence: 99%

Robust Self-Healing Concrete for Sustainable Infrastructure

Herbert

2012

ACT

Self Cite

253

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This article introduces the concept of self-healing concrete for sustainable infrastructure through reduction of maintenance and repair in the use phase. To realize this goal, self-healing must observe at least six robustness criteria -long shelf life, pervasive, quality, reliable, versatile, and repeatable. Five broad categories of self-healing approaches, namely chemical encapsulation, bacterial encapsulation, mineral admixtures, chemical in glass tubing, and intrinsic healing with self-controlled tight crack width, are evaluated against the robustness criteria. It is suggested that while significant progress has been made over the last decade in laboratory studies, important knowledge gaps must be filled in all categories of self-healing approaches to attain the goal of smart sustainable infrastructures that possess self-repair capability in the field.

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“…It is known that healing products not only seal cracks, but substantially improve stiffness and ultimate tensile strength upon reloading [3,4]. Chemical characterization of the healing products themselves, however, has received limited attention.…”

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confidence: 99%

Microanalysis of Autogenous Healing Products in Engineered Cementitious Composites (ECC)

Sakulich

Kan

2010

Microsc Microanal

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Cracking is a major problem in cementitious systems. It can be caused by loading, creep, shrinkage, chemical attack, or cycles of thermal expansion and contraction. Whatever the cause, cracking inexorably leads to lowered durability in the form of reduced mechanical properties and inability to protect reinforcing steel. The ability of a material to self-heal, that is to heal cracks without resort to external media, has been termed autogenous healing [1]. In a perfect system, autogenous healing would occur automatically upon the creation of a crack and would not require any external influence. The crack would be both sealed (reducing flow of liquids through the material) and, more importantly, healed, (restoring the material's mechanical properties). A cementitious material capable of robust autogenous healing would have a substantially higher durability, longer life, lower overall cost, and would be more environmentally friendly.Autogenous healing of cementitious materials occurs due to one of two mechanisms: either the hydration of unreacted cement particles or the carbonation of portlandite crystals, both of which are exposed during cracking. A number of studies on ordinary cement have shown the production of calcite to be the most important, and sometimes only, mechanism at work. Autogenous healing, via these mechanisms, occurs only in the presence of water, and only in very fine cracks below roughly 50 µm wide. The autogenic healing capabilities of ordinary cementitious materials are poor, as the crack size cannot be controlled or predicted, and is often far too large for autogenous healing to occur ( fig. 1a).Engineered Cementitious Composites (ECCs) are a class of ultra-ductile, micromechanically designed, fiber-reinforced cementitious composites [2]. The high ECC tensile strain capacity of above 3% is due to distributed microcracking produced by low loadings (< 2%) of polymer fibers ( fig. 1b). These microcracks are small enough to be autogenously healed, and can be custom tailored depending on application.Much work on autogenous healing in ECC has focused on mechanical properties. It is known that healing products not only seal cracks, but substantially improve stiffness and ultimate tensile strength upon reloading [3,4]. Chemical characterization of the healing products themselves, however, has received limited attention.A number of microanalysis techniques, such as FTIR, Raman, and energy dispersive spectroscopies complimented by x-ray diffraction have been used to characterize self healing products in ECC. The data show that the product is a mixture of both hydrated cement and calcite. The FTIR results in particular suggest that the calcite is not being produced by carbonation of portlandite, but rather by CO 3 2-ions in solution stripping calcium from the calcium silicate hydrate (C-S-H) phase of the 1220

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Autogenous healing of engineered cementitious composites under wet–dry cycles

Cited by 575 publications

References 11 publications

Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

Robust Self-Healing Concrete for Sustainable Infrastructure

Microanalysis of Autogenous Healing Products in Engineered Cementitious Composites (ECC)

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