Influence of Mineral Admixtures on the Rheology of Cement Paste and Concrete.
Influence of Mineral Admixtures on the Rheology of
Cement Paste and Concrete.
Ferraris, C. F.; Obla, K. H.; Hill, R.
Cement and Concrete Research, Vol. 31, No. 2, 245-255,
concretes; cement paste; rheology; mineral admixtures;
test methods; rheometers; mini-slump; marsh cone
Rheological tests on cement paste were used to
successfully select the type and dosage of mineral
admixtures that improved concrete workability. Among the
six different mineral admixtures tested, the ultra fine
fly ash (UFFA), was determined to give the best results
by reducing the yield stress and viscosity. These
improved rheological properties were not achieved by
increasing the water demand and/or the high range water
reducer admixtures (HRWR) dosage. Therefore, the
addition of UFFA improved the concrete flow without a
potential decrease of the hardened properties or an
increase in cost. The conclusions reached based on
cement paste tests were validated by concrete slump
tests. The cement paste rheological data were also
compared using two simpler tests, mini-slump and Marsh
cone. The goal was to determine whether the simpler
tests could be used to characterize the rheology of
cement paste adequately. The conclusions are that these
simpler tests are unreliable for measuring workability.