Influence of the partial replacement of cement by ultrafine rice husk ash with high-carbon content on the properties of concrete

This paper describes the use of ultrafine rice husk ash with high-carbon content in ordinary and high-strength concretes. The influence of ultrafine ash (10, 15 and 20% of cement replacement, in mass) on rheology (yield stress and plastic viscosity), compressive strength (7, 28, 90, and 180 days) and rapid chloride-ion penetrability was investigated. In addition, two experiments were carried out on an adiabatic calorimeter to investigate the exothermic behavior of a reference concrete and conventional concrete with 15% ultrafine ash. The results indicated that the addition of ultrafine rice husk ash improved the evaluated properties for both types of concrete.