Assessment of the recycling potential of fresh concrete waste using a factorial design of experiments


Recycling of industrial wastes and by-products can help reduce the cost of waste treatment prior to disposal and eventually preserve natural resources and energy. To assess the recycling potential of a given waste, it is important to select a tool capable of giving clear indications either way, with the least time and work consumption, as is the case of modelling the system properties using the results obtained from statistical design of experiments. In this work, the aggregate reclaimed from the mud that results from washout and cleaning operations of fresh concrete mixer trucks (fresh concrete waste, FCW) was recycled into new concrete with various water/cement ratios, as replacement of natural fine aggregates. A 3(2) factorial design of experiments was used to model fresh concrete consistency index and hardened concrete water absorption and 7- and 28-day compressive strength, as functions of FCW content and water/cement ratio, and the resulting regression equations and contour plots were validated with confirmation experiments. The results showed that the fresh concrete workability worsened with the increase in FCW content but the water absorption (5-10 wt.%), 7-day compressive strength (26-36 MPa) and 28-day compressive strength (32-44 MPa) remained within the specified ranges, thus demonstrating that the aggregate reclaimed from FCW can be recycled into new concrete mixtures with lower natural aggregate content. (C) 2009 Elsevier Ltd. All rights reserved.



subject category

Engineering; Environmental Sciences & Ecology


Correia, SL; Souza, FL; Dienstmann, G; Segadaes, AM

our authors


This research was supported by the UDESC-Joinville project DAPE 09/2006 (S.L. Correia). The authors appreciate the financial support received from the Brazilian Research Agency CNPq (G. Dienstmann, grant) and are thankful to Concrebras (Joinville, SC) for providing the fresh concrete waste mud used throughout the work.

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