Blast-furnace slag (GBFS) and silica fume (SF) are
produced as by-product from chemical industries with limited
recycling facility. This paper represents an experimental study
aimed to produce cementless binding material using both of
sodium hydroxide (SH) and waterglass liquid (SSL) as alkaline
activator. The alkaline activation of GBFS-SF has been studied by
using electrical conductivity, FT-IR, DTA/TGA, XRD and SEM
techniques. As the hydration time increases the amount of
hydration products increase. The chemically combined water and
combined slag contents increase with curing ages. SEM images
showed the presence of C-S-H and (N,C)-A-S-H gel with low
porosity. The alkali activated GBFS-SF pastes are more durable in
5% MgSO4 or 5% MgCl2 solution than ordinary Portland cement
(OPC) up to 180 days. The total chloride and total sulphate
contents decrease with alkali activated GBFS-SF due to the
formation of hydrated products, which fill the available open
pores, thereby inhibit Cl- or SO4
2- ions penetration; this effect
leads to a decreased accessibility of Cl- or SO4
2- ions towards the
more dense close structure with low capillary pore structure. |
