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<p>The formation of
the cracks in concrete materials can shorten the service life of the structure
by exposing the steel rebar to the aggressive substances from the external
environment. Self-healing concrete can eliminate the crack automatically, which
has the potential to replace manual rehabilitation and repairing work. This
thesis intends to develop a self-healing fiber-reinforced cementitious
composite by the use of internal curing agents, such as lightweight aggregate,
zeolite and superabsorbent polymer (SAP). This study has evaluated the crack
width control ability of three different types of fiber, polyvinyl alcohol
fiber (PVA), Masterfiber Mac Matrix and Strux 90/40 fiber. Mechanical
performance and flexural stress-strain behavior of the fiber-reinforced
cementitious composite were tested and compared. In order to investigate the
feasibility of using internal curing aggregate to enhance autogenous healing
performance, two types of porous aggregates, zeolite and lightweight aggregate
(LWA), were used as internal curing agents to provide water for the autogenous
healing. The pore structure of the zeolite and lightweight aggregate was examined
by the scanning electron microscopy (SEM). Two replacement ratios of sand with
internal curing aggregates were designed and the healing efficiency was
evaluated by the resonant frequency measurement and the optical microscopic
observation. To further understand the influence of the internal curing on the
designed material, water retention behavior of the bulk sample and the internal
curing aggregates was evaluated. Moreover,
to study the self-sealing effect of the superabsorbent polymer (SAP), the
robustness of the SAP under various environmental conditions was first evaluated.
The influence of the superplasticizer, hydration accelerator and fly ash on the
absorption behavior of the SAP was investigated by the filtration test and void
size analysis. Afterward, the self-sealing performance of the SAP in cement
paste was evaluated by a water flow test.</p>
<p>The evaluation
of three types of fiber indicated that the use of PVA fiber could produce a
cementitious composite with stronger mechanical strength and crack width
control ability. The result of the autogenous healing evaluation showed that
the incorporation of the internal curing aggregates increased the self-healing
recovery ratio from 12.6% to over 18%. The internal curing aggregate could
absorb and store water during the wet curing and release it when the external
water supply is unavailable. The comparison between the two types of internal
curing aggregates indicated that finer pores in the internal curing aggregate
can lead to a slower water release rate that is capable of continuously supplying
water for the autogenous healing. In addition, the SAP was proved to be robust
when various content of the additives and fly ash were used. And the
self-sealing effect of the SAP is found to be effective in regaining the water
tightness of cement paste. The result of this thesis can assist in the design
of the fiber-reinforced cementitious composite with self-healing performance in
civil engineering.</p>
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| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12731132 |
| Date | 30 July 2020 |
| Creators | Cihang Huang (9179918) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/EVALUATING_THE_SELF_HEALING_BEHAVIOR_OF_THE_FIBER-REINFORCED_CEMENTITIOUS_COMPOSITE_INCORPORATING_THE_INTERNAL_CURING_AGENTS/12731132 |
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