Characterization of the interface between brick and mortar

dc.contributor.author Chase, Gerald
dc.contributor.department Civil, Construction, and Environmental Engineering
dc.date 2018-08-15T05:57:46.000
dc.date.accessioned 2020-07-02T06:06:44Z
dc.date.available 2020-07-02T06:06:44Z
dc.date.copyright Sat Jan 01 00:00:00 UTC 1983
dc.date.issued 1983
dc.description.abstract <p>Although mortar has been performing its role of holding masonry structures together for hundreds of years, masonry does fail, and the majority of cases of failure occur at the interface between the mortar and the masonry unit. The purpose of this investigation was to examine that interface in more detail, using a combination of crossed-couplet bond tests, the scanning electron microscope, and X-ray diffraction. Several brick pretreatments were also evaluated. Previous investigations of tensile bond strength have shown that bond strength is affected by brick suction, brick surface texture, mortar flow and composition, and other factors. But they did not examine the fundamental mechanism of bonding, nor the chemistry at the interface;The crossed couplet testing done as a part of this investigation examined the effect of NaOH, limewater, and H(,3)PO(,4) pretreatments applied to the brick. For type S mortar, these pretreatments have a significant beneficial effect on tensile bond strength, when compared to water only, or dry brick. Pre-wetting the brick was shown to have a beneficial effect on the bond strength;Scanning electron microscope (SEM) photographs of the interface region show that the preponderant materials present for untreated brick are calcium-silicate-hydrate (C-S-H) and calcium hydroxide. Micrographs of brick treated with NaOH and H(,3)PO(,4) show the presence of complex crystals at the interface, which may account for the increased tensile bond strength observed with these treatments. Energy dispersive X-ray analysis (EDXA) performed on the SEM samples provides clues as to the possible composition of interfacial compounds, but additional means are needed for positive identification;X-ray diffraction of cement and lime paste and untreated brick shows that there is evidence of an increase in crystalline Ca(OH)(,2) beyond that which would be expected. X-ray diffraction confirms the presence of a reaction product between paste and brick treated with H(,3)PO(,4) or NaOH. However, positive identification has not been made;Additional investigations are recommended to determine the identity of the reaction products mentioned above, to test the durability and water resistance of chemically treated brick assemblages, and to perform more extensive couplet testing using mortars of different composition and flow.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/8411/
dc.identifier.articleid 9410
dc.identifier.contextkey 6333775
dc.identifier.doi https://doi.org/10.31274/rtd-180813-7996
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/8411
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/81397
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/8411/r_8316144.pdf|||Sat Jan 15 02:11:20 UTC 2022
dc.subject.disciplines Civil Engineering
dc.subject.keywords Civil engineering
dc.subject.keywords Geotechnical engineering
dc.title Characterization of the interface between brick and mortar
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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