The use of a new cement mixture made by slags and C&D aggregate in the construction of a urban ring-road

During construction of the Padova ring-road (major road with dual carriageway), a new material has been experimented for the road foundation. It is a mixture made of foundry slags from metallurgical industry, C&D (construction and demolition) material, water and CEM 32.5R cement. The mix, which has a binder content that can be varied up to 4%, has a C.B.R. Index of above 100% and good short-term mechanical properties (after 7 days: compressive strength up to 2 MPa, indirect tensile strength up to 0.4 MPa, dynamic elastic modulus up to 6,000 MPa). Chemical analysis excludes the hazardousness of the mixture as well as its toxicity due to the leaching effect of water. The material has been proposed for a heavy-duty road pavement (subject to 45 million 8.2 ton axles over a period of 20 years), composed of 12 cm bituminous surfacing, 12 cm bituminous road base and 35 cm C&D+slag foundation. After laying the material, tests were done on the cement mixture which confirmed the high performances of the product (5 days modulus from a plate-bearing test higher than 300 MPa).