Pavement construction using road waste building material – from a model to reality

Abstract

Using waste building materials in pavements is one of the goals of transportation sustainable development in the Czech Republic. As part of research projects of the Technology Agency of the Czech Republic, a project was devised, which focused on maximal utilisation of waste building materials when constructing pavements. Up until now, bound layers were less common in the Czech Republic. This fact was due to a common formation of reflexive cracks, which quickly propagate themselves upwards to the asphalt surface layers and thus reduce the lifetime and reliability of such pavements. Nowadays, with the increasing traffic intensity and with the introduction and development of new modifications and technologies aimed at eliminating crack propagation, they are more and more often used as base courses of flexible and rigid pavements. In order to prove the possibility of using waste building materials in these courses, we proceeded by first determining the general strength properties in accordance with European standards, then built a full-scale model of a pavement with dynamic cyclic loads, and finally performed tests in real conditions on a testing section to be able to finally choose the most well-optimised cement-bound granular mixtures (CBGMs) by functional laboratory analyses. Also, elasticity moduli E of the designed CBGMs were measured during this extensive laboratory and field testing, using cyclic triaxial device and subsequently these values were compared with the resilient moduli values Mr calculated from non-destructive falling weight deflectometer (FWD) tests. Values of resilient modulus Mr of the CBGMs with recycled material calculated from non-destructive FWD test ranged from 10,000 to 22,000 MPa, depending on the amount and type of binder used. In addition, correlations were analysed between elasticity modulus E of CBGMs and other laboratory-determined parameters (compressive strength, indirect tensile strength and compressive strength after frost cycles). The elasticity moduli E of the CBGMs ranged from 800 to 2000 MPa (depending on the amount of the binder). Relationship between E determined by the cyclic triaxial test and Mr determined by the FWD of the designed CBGMs is E = 23 Mr0,91.