Use Of Recycled Aggregate And Expanded Clay For Self-Compacting Lightweight Aggregate Concretes

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Title: Use Of Recycled Aggregate And Expanded Clay For Self-Compacting Lightweight Aggregate Concretes

Author(s): Valeria Corinaldesi and Giacomo Moriconi

Publication: Special Publication

Volume: 305

Issue:

Appears on pages(s): 33.1-33.12

Keywords: expanded clay, fiber reinforced concrete, lightweight aggregate concrete, self-compacting concrete, polypropylene fibers, synthetic fibers, recycled aggregate concrete

Date: 9/1/2015

Abstract:
In this work, fiber reinforced SCLWAC (self-compacting lightweight aggregate concrete) mixtures were studied, in which synthetic fibers were used. Eight different SCLWAC mixtures were prepared, by employing either fly ash or silica fume as mineral addition. In particular, as aggregates, different combinations of fine and coarse expanded clay were tried, also partially replaced by either quartz sand or recycled aggregate coming from a recycling plant, in which rubble from concrete demolition are suitably treated. The SCLWACs were characterized at the fresh state by means of slump flow, V-funnel and L-box tests, and after hardening by means of compression, splitting tension and bending tests, as well as drying shrinkage measurements. Strength class of LC 45/50 was obtained by using synthetic macrofibres when the oven dry density of SCLWAC was about 1600 kg/m3 [2700 lb/yd3], while if the oven dry density of SCLWAC was lower than 1250 kg/m3 [2100 lb/yd3] a strength class of LC 25/28 was reached as well. Splitting tensile and flexural strength measured values were consistent with concrete strength class, while the elastic modulus was quite low with respect to normal weight self-compacting concrete (SCC). The post-cracking behaviour of SCLWAC resulted strongly improved by the addition of synthetic macrofibers, which proved to guarantee a softening behaviour in flexure. In conclusion, the addition of synthetic fibers allowed to design special concretes with excellent combination of mechanical and functional properties.