Evaluation of fresh properties of controlled low-strength material produced from water treatment sludge-fly ash-slag mixture using alkaline activation

Abstract

This study used a sodium hydroxide (NaOH) solution to activate a mixture of water treatment sludge, fly ash, and slag, in order to produce a new alkali-activated controlled low-strength material (CLSM). Fresh properties of this new CLSM were investigated through the tests of workability, setting time, and ball drop time. Test results show that the addition of water treatment sludge (WTS) decreased workability. In addition, the addition of such WTS increased initial setting time and ball drop time, whereas the alkali equivalent (AE) shortened the initial setting time and ball drop time. At a liquid-to-solid ratio (L/S) of 0.9, a WTS content of 10%, and an alkali equivalent of 9%, the fresh properties for the CLSM conforms to the design principles and provisions of the Public Works Department, Taipei City Government, and is ideal for road construction in order to reduce traffic impact.