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S. Grzeszczyk and K. Jurowski
4 Test Methods
Cement particle size distribution was tested by means of a particle size laser
analyzer—Mastersizer 3000 with a wet dispersion method. Isopropyl alcohol was
used as a dispersant.
Consistency of the concrete mixture was tested with a slump-flow test method,
in accordance with PN-EN 12350-8:2012. The flow diameter (d) and flow time to
500 mm (t 500 ) were determined.
Washout of concrete mixtures was tested in line with CRD-C 61-89A standard.
5 Results and Discussion
5.1 Chemical Structure of Anti-Washout Admixture (AWA)
and Its Action
The chemical structure of AWA, defined in the paper [21], based on a Fouriertransform infrared spectroscopy (FTIR) and thermogravimetric analysis, derivative
thermogravimetric analysis (TGA-DTG), was used to explain the impact of the blast
furnace slag of various fineness and SiO 2 particles added to the cement on the washout
of the concrete mix. Tests showed that AWA contains 42.2% of a polymer organic
phase and 53.6% of calcium carbonate (chalk) with a small admixture of silicates
and/or aluminosilicates.
Based on FTIR and TGA/DTG analyses, it was confirmed that the AWA polymer
includes three types of cellulose derivative chains performing various functions in
the concrete mixture. These are: methyl cellulose ethers, polyoxyethylene cellulose
ethers and carboxy cellulose. The methyl cellulose ethers’ chains are responsible for
AWAs dissolution in water and formation of colloid which radically increases the
medium’s viscosity and contributes to water retention in the composition. This takes
place thanks to the development of hydrogen bonds between water particles and the
oxygen atoms of methoxyl groups. On the other hand, polyoxyethylene cellulose
ethers’ chains undergo hydration in a water environment and each oxygen atom of
the C-O-C ether group can bind two water particles using a hydrogen bond, thereby
straightening twisted polyoxyethylene chains in a water environment. Furthermore,
polyoxyethylene chains take part in the development of transverse bonds (bridges)
between adjacent methyl cellulose chains, thereby creating a dense spatial network
constituting a trap for cement paste’s fine fractions. This leads to water retention in the
composition and increase in environmental viscosity. On the other hand, the COO
−
carboxylate groups of sodium salt in a carboxyl cellulose chain are responsible for
the electrostatic anchoring of the AWA polymer on particles of fine fractions of the
cement paste.
S. Grzeszczyk and K. Jurowski
4 Test Methods
Cement particle size distribution was tested by means of a particle size laser
analyzer—Mastersizer 3000 with a wet dispersion method. Isopropyl alcohol was
used as a dispersant.
Consistency of the concrete mixture was tested with a slump-flow test method,
in accordance with PN-EN 12350-8:2012. The flow diameter (d) and flow time to
500 mm (t 500 ) were determined.
Washout of concrete mixtures was tested in line with CRD-C 61-89A standard.
5 Results and Discussion
5.1 Chemical Structure of Anti-Washout Admixture (AWA)
and Its Action
The chemical structure of AWA, defined in the paper [21], based on a Fouriertransform infrared spectroscopy (FTIR) and thermogravimetric analysis, derivative
thermogravimetric analysis (TGA-DTG), was used to explain the impact of the blast
furnace slag of various fineness and SiO 2 particles added to the cement on the washout
of the concrete mix. Tests showed that AWA contains 42.2% of a polymer organic
phase and 53.6% of calcium carbonate (chalk) with a small admixture of silicates
and/or aluminosilicates.
Based on FTIR and TGA/DTG analyses, it was confirmed that the AWA polymer
includes three types of cellulose derivative chains performing various functions in
the concrete mixture. These are: methyl cellulose ethers, polyoxyethylene cellulose
ethers and carboxy cellulose. The methyl cellulose ethers’ chains are responsible for
AWAs dissolution in water and formation of colloid which radically increases the
medium’s viscosity and contributes to water retention in the composition. This takes
place thanks to the development of hydrogen bonds between water particles and the
oxygen atoms of methoxyl groups. On the other hand, polyoxyethylene cellulose
ethers’ chains undergo hydration in a water environment and each oxygen atom of
the C-O-C ether group can bind two water particles using a hydrogen bond, thereby
straightening twisted polyoxyethylene chains in a water environment. Furthermore,
polyoxyethylene chains take part in the development of transverse bonds (bridges)
between adjacent methyl cellulose chains, thereby creating a dense spatial network
constituting a trap for cement paste’s fine fractions. This leads to water retention in the
composition and increase in environmental viscosity. On the other hand, the COO
−
carboxylate groups of sodium salt in a carboxyl cellulose chain are responsible for
the electrostatic anchoring of the AWA polymer on particles of fine fractions of the
cement paste.