Abstract
The paper studies the influence of addition of viscosity enhancing biopolymers (diutan gum, gellan gum, xanthan gum, carrageenan, and sodium salt of alginic acid) in the doses of 0.1%, 0.5% and 1% on the fresh state, and physical-mechanical properties of hardened mortars. The mortars were prepared with the constant water/binder ratio and the binder/aggregate ratio of 1:3 by weight. The properties have been studied after 7 and 28 days of curing time. All the admixtures, with the exception of gellan gum, improved workability (by lowering the value of spread) in comparison with reference mortar. Most of them also increased the amount of air on the fresh mortar, thus decreasing the density of fresh mortar and also the bulk density of hardened specimens. The addition of biopolymers caused certain decrease of strengths, but there was observable trend of decreasing difference between the reference and tested mortars with the increasing amount of time.
Highlights
The viscosity enhancing admixtures (VEA’s) are widely used in the building materials especially in concrete and dry mix mortars
The biopolymers used can be diversified in two basic groups: seaweed biopolymers [alginic acid sodium salt (ALGNA), carrageenan (CG)], and microbial (gellan gum (GeG), xanthan gum (XG), and diutan gum (DG))
The paper studied the influence of several different biopolymers on the properties of aerial lime-based mortar
Summary
The viscosity enhancing admixtures (VEA’s) are widely used in the building materials especially in concrete and dry mix mortars. The most common biopolymer admixtures are cellulose ethers but the use of guar gum, chitosan ethers, diutan gum, and xanthan gum is expanding [1]. The sodium salt of alginic acid, gellan gum, xanthan gum, diutan gum and carrageenan. The biopolymers used can be diversified in two basic groups: seaweed biopolymers [alginic acid sodium salt (ALGNA), carrageenan (CG)], and microbial (gellan gum (GeG), xanthan gum (XG), and diutan gum (DG)). Carrageenan, in building materials, was tested as admixture for fly-ash geopolymer, where its addition considerably increased strengths, mainly by creating more condensed structure [5]. Use of carrageenan in cementbased material is reported only as a foam-stabiliser for preparing extremely porous cementitious foam, where the low strength was mainly caused by porosity and not the biopolymer addition [6].
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