Edinburgh Napier University

  Direct electric curing is the method by which the hydration reactions within concrete are
thermally accelerated by passing an alternating electric current through the sample. This
use of electricity as a means of supplying heat to young concrete and mortar has become
recognised as a more effective and energy efficient form of accelerating the curing
process than traditional steam curing.
The present investigation involves studying the affects of thermally accelerated curing
of cementitious materials in comparison to normally non-heated curing. Prior to
mixing, tests are performed on the constituents of the cementitious mixes. Results of
these tests are used in the creation of mix designs for mortar and concrete samples. A
range of concrete mixes are designed with and without additives and admixtures are
used to make cubes, slabs and beams.
From the testing results, the factors affecting the short and long term properties of
electrically cured cementitious materials are investigated and heating regimes are
presented to achieve specific properties of both strength and durability at specific ages.
A substantial section of reinforced concrete is required to gain representative results in
electrically curing reinforced concrete slabs. Compressive strength is difficult to
measure due to the electrical distortion affects of inserts and the damage caused by
coring so that at present, basic maturity concepts are used as a compressive strength
guide which limits the validity of results obtained. This research looks at refining these
concepts to include early age heating effects induced by direct electric curing.
The microstructural development of concrete when subjected to accelerated curing is
also considered. The affect of delay periods and maximum temperature is studied using
a scanning electron microscope and the results presented.