Microstructure investigation of the interface between lightweight concrete and normal-weight concrete

0508338 - ÚTAM 2020 RIV NL eng J - Journal Article
Huang, H. - Yuan, Y. - Zhang, Wei - Liu, B. - Viani, Alberto - Mácová, Petra
Microstructure investigation of the interface between lightweight concrete and normal-weight concrete.
Materials Today Communications. Roč. 21, December (2019), č. článku 100640. ISSN 2352-4928. E-ISSN 2352-4928
Institutional support: RVO:68378297
Keywords : interfacial transition zone * lightweight concrete * micro-hardness test * scanning electron microscope * Raman spectroscopy
OECD category: Materials engineering
Impact factor: 2.678, year: 2019
Method of publishing: Limited access
https://doi.org/10.1016/j.mtcomm.2019.100640

Lightweight concrete (LWC) and normal weight concrete (NWC) are used in combination in structural engineering practice. Introduction of LWC brings advantages in terms of energy efficiency and reduction of costs. The mechanical properties of the interfacial transition zone (ITZ) between LWC and NWC has a crucial effect on the durability of structures. In this study, the bond properties of normal weight concrete-to-lightweight concrete (NWC-to-LWC) and lightweight aggregates-tocement paste (LWA-to-CP) have been investigated at the microscale conducting microhardness tests and scanning electron microscope observations, whereas phase composition at the ITZ was measured with micro-Raman spectroscopy. The results indicated that the micro-hardness profile across the NWC-to-LWC ITZ is 'U-shaped' and is surrounded by many fine cracks. The minimum in micro-hardness corresponds to a higher concentration of hydration products and ettringite. The LWA-to-CP ITZ is narrower, it appears compact with an asymmetric micro-hardness profile, thicker on the side of the cement paste (about 50 μm). On this side, a weak zone, with hardness lower than the one of the cement paste and enriched in ettringite and carbonated Ca(OH)2, is observed.
Permanent Link: http://hdl.handle.net/11104/0299371