Practical experience of construction of concrete pavement using non-conditional aggregates

The ways of involving iron ore tailings in road construction are shown in this paper on example of alkali-activated slag cements used as a binding material. The results of the study showed that in case of the alkali-activated slag cements the compacted concrete mixtures for bases could incorporate up to 40 % of iron ore tailings, and with addition of up to 10 % of fly ash by mass – up to 60 % by mass with providing the required compressive strength (>2 MPa) and coefficient of softening (in water) (not lower than 0.8). The results suggested to show that with increase in quantities of the alkaline component the strength tended to increase, and that addition of fly ash was favourable in terms of consistency of the concrete mixture and time of workability retention. The concrete with 100 % replacement of fine aggregate by iron ore tailings exhibited compressive strength of 30 MPa and the concrete mixture had a consistency of classes S3-S4 as per EN 206-1:2000. This concrete mixture of optimal composition was used as paving in the construction of a pilot road (length 50 m, width 4 m, and thickness 0.3 m) in Qianxi (Tianshan, P.R.China).