Development of high-volume low-lime and high-lime fly-ash-incorporated self-consolidating concrete

摘要

The current article presents an experimental study on the use of two types of fly ash (low lime and high lime) as mineral admixtures in producing self-consolidating concrete (SCC) with the objective of assessing the effects of both types of fly ash on the fresh and hardened properties of SCCs. Within the scope of an experimental programme, SCCs were prepared by keeping the total mass of cementitious materials constant at 500 kg/m~3, in which 30, 40, 50, 60 or 70% of cement, by mass, was replaced by high-lime and low-lime fly ash. The workability-related fresh properties of SCCs were observed through slump flow time and diameter, V-funnel flow time, L-box height ratio, GTM sieve stability test and the rheological parameters (relative yield stress and relative plastic viscosity). Setting times and temperature rise of SCCs were also determined as part of fresh properties. The hardened properties that were monitored for a year included the compressive strength, ultrasonic pulse velocity, drying shrinkage and chloride permeability. It was observed that the geometry and surface characteristics of fly ash affected the workability properties of SCC mixtures. Nonetheless, the compressive strength of SCC mixtures with 30—40% low-lime fly ash replacement was slightly greater than the control SCC mixture at the end of the year, as the amount of fly ash replacement increased losses in compressive strength. As a result of this experimental study, it could be concluded that SCCs incorporating a fly ash replacement of 70% could be produced with improved fresh and permeation properties and sufficient compressive strength.