Experimental Evaluation of Recycled Aggregates, Washing Water and Cement Sludge Recovered from Returned Concrete

Abstract

In this paper, a new innovative technology for the treatment of returned concrete is proposed. This method is based on the application of physical–mechanical processes that allow to obtain new quality products: recycled aggregates, microfiltered water and cement sludge. Specifically, by means of a mechanical system equipped with buffer and Archimedes screws, fine (d < 5 mm) and coarse (d > 5 mm) aggregates are obtained. The water coming from the washing process is sent to a microfiltration process, where a filter membrane separates the liquid phase (microfiltered water) from the solid phase (cement sludge) and no type of potentially toxic additive is added. In this context, this paper investigates the feasibility of using all these components as new raw materials for sustainable concrete production. In particular, according to the requirements imposed by technical standards, an experimental program was developed, aimed at evaluating the physical, chemical, and mechanical properties of the analyzed materials. The results showed that both recycled aggregates, the microfiltered water and the cement sludge can be used to produce new structural concrete. In particular, it was proven that also the cement sludge, which generally represents the most critical component destined for disposal, can be reused as filler in the partial replacement of sand.

Technical and Environmental Properties of Recycled Aggregates Produced from Concrete Sludge and Excavation Materials

“…Regarding RCZ0, reported similar values in a study that investigated the mechanical performance of recycled aggregates derived from EM. Other studies have also reported the density for recycled aggregates obtained from ready mixed concrete waste within the range 1.65-2.72% [11,16,20,26]. It can also be mentioned that Norwegian rocks typically have a density within the range of 2.65-3.10 g/mL [16].…”

Study on Circular Economy Implementation Propensity of Construction Companies in Context of Prevailing Management Styles

“…The circular economy, as an idea on the one hand, and as real action on the other hand, supports the construction industry by reducing its negative impact on the environment. Nowadays, mainly practical examples relating to concrete [35] and asphalt [36] technologies dominate the literature. However, this concept applies to every material and can be viewed from different angles represented by the various players involved in the Each working package related to the implementation of a new production effect is characterized by standard material usage.…”