EFFECT OF HIGH VOLUME REPLACEMENT OF FINE AGGREGATE WITH BOTTOM ASH ON FLOW, SETTING TIME, COMPRESSIVE STRENGTH AND SHRINKAGE OF MORTAR

Abstract

This research is to study the effect of high volume bottom ash, as a
replacement of fine aggregate, on flow, rate of flow loss, setting time,
compressive strength and shrinkage of mortar. Behaviors of the mortar in each
situation are compared. Two types of mortar, one with solely the river sand
(control mortar) and the other with bottom ash for 45% by volume of total
fine aggregate, were studied with the water to binder ratios of 0.35 and 0.50. In
the case of water to binder ratio = 0.35, there is also the case where fly ash is
used as a partial replacement of cement. The results show that, the initial flow
and flow at 2 hours of mixtures with high volume bottom ash were higher than
those of the control mortar, but the setting time did not change significantly. In
addition, the replacement of sand with bottom ash does not reduce the
compressive strength while the autogenous shrinkage is reduced. Nevertheless,
the replacement of sand with bottom ash increases the total shrinkage
because of higher drying shrinkage. The results also showed that, the mixtures
using fly ash as a part of the binder, and bottom ash as a fine aggregate, in
case of water to binder ratio = 0.35, have similar setting time and kept total
shrinkage to those of the control mortar.