Confined-direct electric curing of NaOH-activated fly ash based brick mixtures under free drainage conditions : Part 2. Confined-DEC versus oven curing

Abstract

A novel accelerated curing technique – confined-DEC (Direct Electric Curing) – was compared with oven curing. Microstructural investigations revealed that under free drainage conditions non-uniform curing conditions were induced within NaOH-activated fly ash based brick mixture during confined-DEC. Strength development of the outer-core (surface) regions of the mixture was impaired by diminished alkali content due to movement of pore solution, resulting in lower compressive strength at later ages compared to identical mixtures cured in an oven for 16 h. Nevertheless, confined-DEC is a promising technique for brick mass production as the requirements of several strength classes of the South African concrete masonry units’ standard SANS 1215:2008 were met in 7 min.