Change search
Link to record
Permanent link

Direct link
BETA
Habermehl-Cwirzen, KarinORCID iD iconorcid.org/0000-0001-7279-6528
Alternative names
Publications (10 of 27) Show all publications
Buasiri, T., Habermehl-Cwirzen, K., Krzeminski, L. & Cwirzen, A. (2019). Piezoresistive Load Sensing and Percolation Phenomena in Portland Cement Composite Modified with In-Situ Synthesized Carbon Nanofibers. Nanomaterials, 9(4), Article ID 594.
Open this publication in new window or tab >>Piezoresistive Load Sensing and Percolation Phenomena in Portland Cement Composite Modified with In-Situ Synthesized Carbon Nanofibers
2019 (English)In: Nanomaterials, ISSN 2079-4991, Vol. 9, no 4, article id 594Article in journal (Refereed) Published
Abstract [en]

Carbon nanofibers (CNFs) were directly synthesized on Portland cement particles by chemical vapor deposition. The so-produced cements contained between 2.51–2.71 wt% of CNFs; depending on the production batch. Several mortar mixes containing between 0 and 10 wt% of the modified cement were produced and the electrical properties at various ages and the load sensing capabilities determined. The percolation threshold related to the electrical conductivity was detected and corresponded to the amount of the present CNFs, 0.271, 0.189, 0.135 and 0.108 wt%. The observed threshold depended on the degree of hydration of the Portland cement. The studied mortars showed a strong piezoresistive response to the applied compressive load reaching a 17% change of the electrical resistivity at an applied load of 3.5 MPa and 90% at 26 MPa. This initial study showed that the studied material is potentially suitable for future development of novel fully integrated monitoring systems for concrete structures.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Carbon nanofibers, CVD, percolation, piezoresistive response, compressive load
National Category
Other Materials Engineering
Research subject
Building Materials
Identifiers
urn:nbn:se:ltu:diva-73574 (URN)10.3390/nano9040594 (DOI)30974888 (PubMedID)
Funder
Vinnova, 2016-03285Swedish Transport Administration, TRV2017/57560
Note

Validerad;2019;Nivå 2;2019-04-15 (oliekm)

Available from: 2019-04-11 Created: 2019-04-11 Last updated: 2019-04-15Bibliographically approved
Tole, I., Habermehl-Cwirzen, K., Rajczakowska, M. & Cwirzen, A. (2018). Activation of a Raw Clay by Mechanochemical Process: Effects of Various Parameters on the Process Efficiency and Cementitious Properties. Materials, 11(10), Article ID 1860.
Open this publication in new window or tab >>Activation of a Raw Clay by Mechanochemical Process: Effects of Various Parameters on the Process Efficiency and Cementitious Properties
2018 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, no 10, article id 1860Article in journal (Refereed) Published
Abstract [en]

The efficiency of the mechanochemical activation (MCA) is influenced by various process parameters as well as by the properties of the treated material. The main objective of this research was to optimize the MCA process, gaining enhancement of the chemical reactivity of a Swedish raw clay, which is going to be used as an alkali-activated cementitious binder. The effects of the amount of water, the filling ratio, the rotation speed, and the grinding duration on the amorphization degree were evaluated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Generally, wet and dry processes showed an extensive amorphization of both kaolinite and muscovite minerals present in the studied clay. On the contrary, quartz was amorphized mainly by the wet grinding process. The efficiency of both dry and wet grinding processes was enhanced by the increased number of grinding media versus the amount of the activated material. However, longer processing times caused significant agglomeration while a higher rotational speed enhanced the amorphization. Preliminary tests have shown that alkali activation of the processed clays produced hardened samples. Furthermore, the increased amorphization corresponded to the increased compressive strength values.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
clay minerals, dry grinding, fine grinding, mechanochemical activation, mechanochemistry, wet grinding
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-71035 (URN)10.3390/ma11101860 (DOI)30274273 (PubMedID)2-s2.0-85054276282 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-03 (marisr)

Available from: 2018-09-30 Created: 2018-09-30 Last updated: 2019-04-02Bibliographically approved
Bohling, D., Cwirzen, A. & Habermehl-Cwirzen, K. (2018). Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization. Advances in Civil Engineering / Hindawi, 2018, Article ID 8197039.
Open this publication in new window or tab >>Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization
2018 (English)In: Advances in Civil Engineering / Hindawi, ISSN 1687-8086, E-ISSN 1687-8094, Vol. 2018, article id 8197039Article in journal (Refereed) Published
Abstract [en]

Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2018
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-70881 (URN)10.1155/2018/8197039 (DOI)000444863000001 ()2-s2.0-85053683394 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-18 (johcin)

Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-10-03Bibliographically approved
Cwirzen, A., Metsäpelto, L. & Habermehl-Cwirzen, K. (2018). Interaction of Magnesia with Limestone-Metakaolin-Calcium Hydroxide Ternary Alkali-Activated Systems. Advances in Materials Science and Engineering, 2018, Article ID 1249615.
Open this publication in new window or tab >>Interaction of Magnesia with Limestone-Metakaolin-Calcium Hydroxide Ternary Alkali-Activated Systems
2018 (English)In: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, Vol. 2018, article id 1249615Article in journal (Refereed) Published
Abstract [en]

The effect of magnesia on ternary systems composed of limestone, metakaolin and calcium hydroxide, alkali activated with sodium silicate, sodium hydroxide, and sodium sulphate was studied by determination of the compressive strength, X-ray powder diffraction (XRD), thermogravimetry (TG), and scanning electron microscope (SEM). Pastes activated with sodium silicate and sodium sulphate showed strength regression caused by a formation of an unstable prone to cracking geopolymer gel. The presence of magnesia in sodium hydroxide-activated system hindered this trend by promoting a formation of more stable crystalline phases intermixed with brucide. In general, magnesia densified the binder matrix by promoting a formation of amorphous phases while sodium hydroxide produced the most porous microstructure containing high amount of crystalline phases.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2018
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-71765 (URN)10.1155/2018/1249615 (DOI)000451174000001 ()2-s2.0-85057381236 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-27 (johcin)

Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2018-12-10Bibliographically approved
Blandine, F., Habermehl-Cwirzen, K. & Cwircen, A. (2017). Erratum to: Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste (ed.) [Letter to the editor]. Frontiers of Structural and Civil Engineering, 11(2), 255-255
Open this publication in new window or tab >>Erratum to: Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste
2017 (English)In: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 11, no 2, p. 255-255Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
Springer, 2017
National Category
Infrastructure Engineering Building Technologies
Research subject
Structural Engineering; Steel Structures
Identifiers
urn:nbn:se:ltu:diva-62772 (URN)10.1007/s11709-017-0395-9 (DOI)000401744300009 ()2-s2.0-85016101056 (Scopus ID)
Available from: 2017-03-29 Created: 2017-03-29 Last updated: 2018-07-10Bibliographically approved
Feneuil, B., Habermehl-Cwirzen, K. & Cwirzen, A. (2016). Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste (ed.). Frontiers of Structural and Civil Engineering, 10(2), 224-235
Open this publication in new window or tab >>Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste
2016 (English)In: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 10, no 2, p. 224-235Article in journal (Refereed) Published
Abstract [en]

In this experimental study, carbon nanotubes (CNTs) and carbon nanofibers (CNFs) were dispersed by intensive sonication in water in the presence of superplasticizer and subsequently mixed with Portland cement with water/ cement ratios varying between 0.3 and 0.4. The autogenous shrinkage in the fresh stage was investigated. The CNTs and CNFs were characterized by high resolution scanning electron microscopy (SEM) and the hydrated pastes were studied by X-ray diffraction and SEM. The results showed a reduction of the autogenous shrinkage by 50% for pastes containing small amounts (0.01 wt%) of nanomaterials. Higher additions appeared to be less effective. The highest reduction of shrinkage was observed for carbon nanofibers which were long, rather straight and had diameters of around 200 nm. The result showed that the addition of nanomaterials accelerated the hydration processes especially in the early stages of hydration. The effect was the most pronounced in the case of functionalized nanotubes. The proposed mechanism resulting in the reduction of the autogenous shrinkage was a combination of nano-reinforcing effects, alterations of hydration and microstructure of the hydrated matrix.

National Category
Infrastructure Engineering Building Technologies
Research subject
Structural Engineering; Steel Structures
Identifiers
urn:nbn:se:ltu:diva-12770 (URN)10.1007/s11709-016-0331-4 (DOI)000382090500012 ()2-s2.0-84962147209 (Scopus ID)bee485ed-19bf-455b-bb5d-cbf8e24b5d1e (Local ID)bee485ed-19bf-455b-bb5d-cbf8e24b5d1e (Archive number)bee485ed-19bf-455b-bb5d-cbf8e24b5d1e (OAI)
Note

Validerad; 2016; Nivå 2; 20160222 (andcwi)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Cwirzen, A., Sztermen, P. & Habermehl-Cwirzen, K. (2014). Effect of baltic seawater and binder type on frost durability of concrete (ed.). Paper presented at . Journal of materials in civil engineering, 26(2), 275-282
Open this publication in new window or tab >>Effect of baltic seawater and binder type on frost durability of concrete
2014 (English)In: Journal of materials in civil engineering, ISSN 0899-1561, E-ISSN 1943-5533, Vol. 26, no 2, p. 275-282Article in journal (Refereed) Published
Abstract [en]

The effects of Baltic seawater on frost durability of PC concretes using sulfate resistant portland cement and combination of rapid hardening portland cement with silica fume were studied. The freeze-thaw cycles were performed on specimens exposed to the Baltic seawater, 3% sodium chloride solution and deionized water. The freeze-thaw cycles appeared to cause the most extensive internal damage in specimens based on sulfate resistant cement (SR) and exposed to seawater. The most extensive surface scaling was observed in the case of concretes containing silica fume and exposed to deicing salts. Based on the thermo gravimetric and X-ray diffraction analyses it was concluded that extensive internal damage of concrete based on SR was caused by changes of the microstructure due to secondary formation of ettringite, carbonation, and formation of calcite. The results showed also that low C3A content of the SR did not fully mitigate formation of secondary ettringite during freeze-thaw cycles. A combination of rapid hardening portland cement and silica fume appeared to form more frost resistant concrete when exposed to seawater. © 2014 American Society of Civil Engineers.

Keywords
Frost attack, Microstrcuture, Seawater, Seawater attack
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-10918 (URN)10.1061/(ASCE)MT.1943-5533.0000803 (DOI)84892864190 (Scopus ID)9cf64558-021f-4dbe-97ef-23f1920b33ce (Local ID)9cf64558-021f-4dbe-97ef-23f1920b33ce (Archive number)9cf64558-021f-4dbe-97ef-23f1920b33ce (OAI)
Note
Upprättat; 2014; 20160222 (andcwi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Cwirzen, A., Engblom, R., Punkki, J. & Habermehl-Cwirzen, K. (2014). Effects of curing: Comparison of optimised alkali-activated PC-FA-BFS and PC concretes (ed.). Paper presented at . Magazine of Concrete Research, 66(6), 315-323
Open this publication in new window or tab >>Effects of curing: Comparison of optimised alkali-activated PC-FA-BFS and PC concretes
2014 (English)In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 66, no 6, p. 315-323Article in journal (Refereed) Published
Abstract [en]

The effects of curing on the mechanical properties, chemical composition, microstructure and shrinkage of optimised alkali-activated concretes (AACs) based on ternary mixtures of fly ash (FA), blast-furnace slag (BFS) and Portland cement (PC) were compared. Heat treatment was found to accelerate the early-age strength development of both the PC concrete and the AAC. The long-term strength of AAC was not adversely affected by the heat treatment after 90 d of dry curing. Water curing slightly enhanced the ultimate long-term strength of non-heat-treated AAC specimens but had barely any effect on the heat-treated specimens. Conversely, the dry-cured PC specimens showed a significant decrease in long-term compressive strength. The ultimate drying shrinkage of the PC concrete was lower compared with the AAC, independent of the type of applied curing. In the case of AAC, the drying shrinkage was significantly decreased by the application of heat treatment while water curing did not have any measurable effect. Conversely, the drying shrinkage of AAC cured at ambient temperatures was decreased with the application of water curing. Compared with the PC concrete, the microstructure of the AAC samples was denser and more homogeneous without visible microcracking of the binder matrix. The dominant phases were geopolymer and calcium silicate hydrate (C-S-H) gels intermixed with probably sodium and aluminium ions and crystalline inclusions of zeolitic hydroxysodalite. A large amount of unreacted FA and BFS was observed in the hardened binder matrix of the AAC specimens. At the same time, no anhydrous PC was observed, thus indicating its extensive dissolution and contribution to the formation of the modified C-S-H gel.

National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-2487 (URN)10.1680/macr.13.00231 (DOI)84896740738 (Scopus ID)01b90a3f-cfb2-4bfd-9a26-89503c2c380f (Local ID)01b90a3f-cfb2-4bfd-9a26-89503c2c380f (Archive number)01b90a3f-cfb2-4bfd-9a26-89503c2c380f (OAI)
Note
Upprättat; 2014; 20160222 (andcwi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Cwirzen, A., Provis, J. L., Penttala, V. & Habermehl-Cwirzen, K. (2014). The effect of limestone on sodium hydroxide-activated metakaolin-based geopolymers (ed.). Paper presented at . Construction and Building Materials, 66, 53-62
Open this publication in new window or tab >>The effect of limestone on sodium hydroxide-activated metakaolin-based geopolymers
2014 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 66, p. 53-62Article in journal (Refereed) Published
Abstract [en]

Blends of metakaolin and limestone can be alkali-activated with NaOH to form solid binders, which show relatively low strength but offer potential as a model system by which the reaction processes of more complex systems can be better understood. The effects of curing procedure, limestone content and alkalinity of the activator are able to be related to the mineralogy, mechanical properties and microstructure of hardened pastes. The presence of limestone enhances the release of Al and Si ions from metakaolin, with the Al released in the early stages of the reaction being bound into AFm-type phases. Dissolution of LS is slightly higher when a lower alkalinity sodium hydroxide activator is used. The heat treatment of pastes activated with 3 M NaOH solution resulted in a lower extent of reaction of limestone, while with 5 M solution, heat-curing at early age resulted in more reaction. The main alkali-activation product in metakaolin-limestone-NaOH pastes is a geopolymer gel with inclusions of unreacted metakaolin, limestone particles, zeolite A, and AFm phases, with different zeolites such as faujasite-like and hydrosodalite phases also identified at higher reaction temperatures. © 2014 Elsevier Ltd. All rights reserved.

Keywords
Alkali-activation, Gel formation, Geopolymer, Limestone, Metakaolin
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-11804 (URN)10.1016/j.conbuildmat.2014.05.022 (DOI)84902122686 (Scopus ID)ad0f89d1-c078-463b-ae00-0692e8021b69 (Local ID)ad0f89d1-c078-463b-ae00-0692e8021b69 (Archive number)ad0f89d1-c078-463b-ae00-0692e8021b69 (OAI)
Note
Upprättat; 2014; 20160222 (andcwi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Cwirzen, A. & Habermehl-Cwirzen, K. (2013). Effects of reactive magnesia on microstructure and frost durability of portland cement-based binders (ed.). Paper presented at . Journal of materials in civil engineering, 25(12), 1941-1950
Open this publication in new window or tab >>Effects of reactive magnesia on microstructure and frost durability of portland cement-based binders
2013 (English)In: Journal of materials in civil engineering, ISSN 0899-1561, E-ISSN 1943-5533, Vol. 25, no 12, p. 1941-1950Article in journal (Refereed) Published
Abstract [en]

The effects of portland cement (PC) replacement with magnesia (reactive magnesium-oxide) on properties of PC-based pastes, mortars, and concretes were investigated. The research included determination of mechanical properties and frost durability in addition to studies of the microstructure and microchemistry. The mortar and paste mixtures contained from 10-80 weight percent (wt%) replacement of PC by magnesia and had water to cementitious-binder ratios from 0.4-0.7, whereas concretes contained from 5-10 wt% magnesia and had a water to cementitious-binder ratio of 0.53. Replacement of PC by magnesia had adverse effects on the mechanical properties and frost durability. The magnesia reduced microcracking of the binder matrix in comparison with pastes containing only PC. The primary hydration product of magnesia was brucite in addition to regular hydration phases of PC. The amount of formed portlandite was increased. Magnesia caused densification of the microstructure but also increased the capillary porosity, resulting in lower frost-durability. © 2013 American Society of Civil Engineers.

Keywords
Forst durability, Magnesia, Microstructure
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-4074 (URN)10.1061/(ASCE)MT.1943-5533.0000768 (DOI)84888071299 (Scopus ID)1efb78db-6192-44ab-96e8-5631f46614d0 (Local ID)1efb78db-6192-44ab-96e8-5631f46614d0 (Archive number)1efb78db-6192-44ab-96e8-5631f46614d0 (OAI)
Note
Upprättat; 2013; 20160222 (andcwi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7279-6528

Search in DiVA

Show all publications