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MICROMECHANICAL CHARACTERIZATION OF CEMENT PASTE MODIFIED BY NANOCLAYS
This work deals with the comparison of micromechanical properties and microstructure of cement pastes with additives used in concrete to reduce the lateral pressure on the formwork. This work is a steppingstone for broader investigation of the lateral pressures on different cement mixtures. The work focused on two additives used for the purpose, namely calcined clay (metakaolin) and a type of nanoclay sepiolite. A scanning electron microscope was used to describe their microstructure. Micromechanical properties of both cement composites were investigated by nanoindentation. Large statistical grids of indents were performed on three sample types: plain cement paste and two mixtures containing the enhancing additive of metakaolin and nanoclay. From the evaluated results in the form of property histograms, the modulus of elasticity, hardness and creep parameter were derived. It was found that in the cement paste with metakaolin the amount of C-S-H gel increased compared to the control mixture. Increased portlandite and the amount of unhydrous clinker was found in the cement paste with nanoclay. Nanomechanical response of individual phases was derived from overall property histograms by statistical deconvolution. The results were confirmed by electron microscopy. The micromechanical research was supplemented with the measurement of the compressive strength on cubes at the macroscopic level.
MICROMECHANICAL CHARACTERIZATION OF CEMENT PASTE MODIFIED BY NANOCLAYS
This work deals with the comparison of micromechanical properties and microstructure of cement pastes with additives used in concrete to reduce the lateral pressure on the formwork. This work is a steppingstone for broader investigation of the lateral pressures on different cement mixtures. The work focused on two additives used for the purpose, namely calcined clay (metakaolin) and a type of nanoclay sepiolite. A scanning electron microscope was used to describe their microstructure. Micromechanical properties of both cement composites were investigated by nanoindentation. Large statistical grids of indents were performed on three sample types: plain cement paste and two mixtures containing the enhancing additive of metakaolin and nanoclay. From the evaluated results in the form of property histograms, the modulus of elasticity, hardness and creep parameter were derived. It was found that in the cement paste with metakaolin the amount of C-S-H gel increased compared to the control mixture. Increased portlandite and the amount of unhydrous clinker was found in the cement paste with nanoclay. Nanomechanical response of individual phases was derived from overall property histograms by statistical deconvolution. The results were confirmed by electron microscopy. The micromechanical research was supplemented with the measurement of the compressive strength on cubes at the macroscopic level.
MICROMECHANICAL CHARACTERIZATION OF CEMENT PASTE MODIFIED BY NANOCLAYS
Zacharda, Vojtěch (author) / Němeček, Jiří (author)
2020-06-11
doi:10.14311/APP.2020.27.0101
Acta Polytechnica CTU Proceedings; Vol 27 (2020): Proceedings of the 14th International Conference on Local Mechanical Properties - LMP 2019; 101-106 ; 2336-5382
Article (Journal)
Electronic Resource
English
metakaolin , nanoclay , Cement , hydration , nanoindentation
DDC:
690
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