Preliminary Observations of Water Movement in Cement Pastes During Curing X-Ray Absorption.
Preliminary Observations of Water Movement in Cement
Pastes During Curing X-Ray Absorption.
Bentz, D. P.; Hansen, K. K.
Cement and Concrete Research, Vol. 30, No. 7,
1157-1168, July 2000.
cements; cement paste; curing; drying; water movement; x
X-ray absorption and concurrent mass measurements are
used in quantifying water movement in 4 mm to 5 mm thick
cement paste specimens with their top surface exposed to
drying. Experimental variables examined in this
preliminary study include water-to-cement (w/c) ratio
and open vs. capped samples. Layered specimens (e.g.,
0.3 w/c ratio paste over 0.45 w/c ratio paste) are also
examined to monitor the preferential water movement from
less dense (higher w/c ratio) paste to denser paste due
to capillary forces. For the open samples examined in
this study, the initial drying is observed to occur
uniformly throughout the thickness of the specimen, as
opposed to proceeding as a sharp front progressing
inward from the surface exposed to the external
environment. In the layered specimens, the higher w/c
ratio paste layer is seen to "dry out" first regardless
of its location within the composite. The implications
of these experimental observations for curing of
concrete and application of repair materials are