Effect of chitosan ethers on fresh state properties of lime mortars

Effect of chitosan ethers on fresh state properties of lime mortars

Paper in proceedings (conference paper)

The fresh state properties of mortars are eminently important since determine the material workability and also have a great influence on its hardened state characteristics. In this paper, the behaviour of fresh lime mortars modified by etherified derivatives of chitosan (hydroxypropylchitosan (HPCH) and carboxymethylchitosan (CMCH)) is assessed with the purpose of exploring a new application of such derivatives as lime mortar admixtures. The rheological parameters (relative yield stress, consistency coefficient and fluidity index) and viscoelastic properties were correlated with flow table tests, relative density measurements, water retention abilities of mortars and air content in mortars. Results were seen to be strongly dependent on substituents of the chitosan. Non-ionic derivative (HPCH) had a plasticizing influence on the mortars; the ionic CMCH showed the thickening effect. The effect of chitosan ethers was found to be dosage-dependent. CMCH had low impact on water retention, while HPCH displayed high water retention capability. It was concluded, that the ionic derivative (CMCH) is very similar by its viscosity enhancing effect to starch ether.

The fresh state properties of mortars are eminently important since determine the material workability and also have a great influence on its hardened state characteristics. In this paper, the behaviour of fresh lime mortars modified by etherified derivatives of chitosan (hydroxypropylchitosan (HPCH) and carboxymethylchitosan (CMCH)) is assessed with the purpose of exploring a new application of such derivatives as lime mortar admixtures. The rheological parameters (relative yield stress, consistency coefficient and fluidity index) and viscoelastic properties were correlated with flow table tests, relative density measurements, water retention abilities of mortars and air content in mortars. Results were seen to be strongly dependent on substituents of the chitosan. Non-ionic derivative (HPCH) had a plasticizing influence on the mortars; the ionic CMCH showed the thickening effect. The effect of chitosan ethers was found to be dosage-dependent. CMCH had low impact on water retention, while HPCH displayed high water retention capability. It was concluded, that the ionic derivative (CMCH) is very similar by its viscosity enhancing effect to starch ether.

lime mortar, chitosan ethers, rheology, water retention, air content, yield stress, viscosity

lime mortar, chitosan ethers, rheology, water retention, air content, yield stress, viscosity

VYŠVAŘIL, M.; ŽIŽLAVSKÝ, T.

2018

25.10.2017

IOP Publishing

3rd International Conference on Innovative Materials, Structures and Technologies (IMST 2017)

1757-8981

IOP Conference Series: Materials Science and Engineering

251

1

United Kingdom of Great Britain and Northern Ireland

1

8

8

http://iopscience.iop.org/article/10.1088/1757-899X/251/1/012039

http://hdl.handle.net/11012/137137

Vyšvařil_2017_IOP_Conf._Ser.__Mater._Sci._Eng._251_012039