Development of bitumen-bound waste aggregate building blocks

The paper describes the optimisation of several mixes for the development of a new range of construction units (Bitublock) composed entirely of recycled and waste aggregates. The development of this new range of building units is driven by the issue of sustainability, both nationally and globally, and this complete replacement of traditional aggregates is possible because Bitublock uses bitumen as the binder. Five main waste materials are considered in this optimisation: crushed glass, pulverised fuel ash (PFA), incinerated bottom ash (IBA), incinerated sewage sludge ash (ISSA) and steel slag. In addition two types of bitumen were also considered: 50 penetration bitumen and harder H 80/90 bitumen. Several properties of the Bitublock were measured to assess their performance in relation to concrete block masonry products found in the UK. These were: shape, density, water absorption, compressive strength, elastic modulus and time-dependent properties. It is shown that all these properties are dependent on the types of aggregate and the binder used, as well as on the compaction pressure and the curing regime. It is clear that Bitublock can be produced with properties that are at least equivalent to those of current concrete block masonry units. The long-term stability of Bitublock is significant in terms of construction, because its use could negate the need for—or at least reduce the frequency of—required movement joints in masonry.