Effect of mixing methods on workability and ultrasound measurements of alkali activated materials

As a new construction material, alkali-activated binders are attracting considerable research. This is due to the use of by-products or waste materials, environmental promises, and comparative performance with ordinary Portland cement binders. Most research in this area is limited to the investigation of mechanical and durability behaviours. A better understanding of their fresh properties and mixing procedures is paramount for better acceptance and application of alkali-activated materials in the construction industry. In this paper, four factors: the total mixing speed, the total mixing time, the length of a rest time, and the time at which the superplasticizer (SP) was added are investigated to understand the effects of the mixing on alkali-activated materials. Three variations are studied for each factor. A self-compacting fine-grained mortar with a maximum grain size of D = 3.15 mm was used. A mixed precursor system containing fly ash (FA), ground-granulated blast-furnace slag (GGBS), and silica fume (SF) is used.