Title: Cementitious, High-Volume Burnt-Oil Shale Binder
Author(s): Theodor A. Burge
Publication: Symposium Paper
Appears on pages(s): 799-814
Keywords: burnt-oil shale; high strength; hydration activator; oil
Oil shale is used for energy production. It was found that burning at about 800°C, according to the ROHRBACH-LURGI Process, resulted in optimal hydraulic properties of the ash. The major problem associated with burning oil shale is the formation of huge quantities of the by-product generally referred to as burnt-oil shale. Depending on the composition of the burnt-oil shale it can be used as an addition to normal portland cement in an amount of 2530% and in various other building products. In view of the fact that huge quantities of burnt-oil shale will be generated, it is beneficial to find ways in using this by-product in a large scale. In some respects burnt-oil shale is a hydraulic material similar in nature to blast-furnace slag. It is cementitious, due to the formation of clinker-like phases, mainly dicalcium silicate and monocalcium aluminate. It also contains, besides small amounts of free CaO and calcium sulfate, larger proportions of pozzolanic reacting oxides, especially amorphous SiO2. Burnt-oil shale has a very slow strength gain and it reaches a compressive strength of about 30 MPa at 28 days. The reactivity of burnt-oil shale can be improved with a hydration activator so that high volume (>50%) burnt-oil shale binders can be produced which show highest reactivity, resulting in extremely high early and final strength and high durability for repair of concrete roads, bridges, runways and the like.