Enabling the use of hydraulically bound quarry by-products in road foundations

Quarrying and crushing of rock to produce aggregate for civil engineering and other purposes generate quarry fines as a by-product. The aim of this research is to develop procedures for their use in road foundations. Initially, laboratory tests were carried out to characterise a wide range of quarry fines from four UK aggregate suppliers. Selected materials were then used as aggregates in hydraulically bound mixtures (HBMs) in a full-scale road trial. Performance foundation designs to the HA document IAN 73 specific for the trial site were formulated for these materials and the foundations were constructed at a quarry by one of the collaborating suppliers. The foundations satisfied in situ requirements of the Performance Related Specification of IAN 73 with little non-compliance and often with a wide safety margin. The study demonstrated that the hydraulically bound, quarry by-products can be mixed and constructed with normal full-scale equipment and can provide the two highest foundation classes of the four classes permitted in IAN 73. The potential of the materials from other aggregate suppliers that were not tested at full-scale was favourably implied by comparison of their laboratory mechanical properties with those of the materials tested in the road trial.