ULTRA-HIGH PERFORMANCE CONCRETES WITH PHENOLIC FOUNDRY SAND: MECHANICAL AND MICROSTRUCTURAL EVALUATION

Abstract

In this investigation, the properties of ultra-high-performance concretes (UHPC) produced with different binders and aggregates were analyzed. Ternary and quaternary mixtures were tested, including structural white Portland cement (WPC), silica fume (SF), hydrated lime (HL), rice husk ash (RHA), fly ash (FA), and limestone filler (LF), in combination with industrial sand (IS) and discarded foundry phenolic sand (DFPS).
 The mixtures underwent two types of curing: moist curing until the testing age and moist combined with thermal curing. The concretes were evaluated for compressive strength and microstructure using thermogravimetric analysis (TG/DTG) and Fourier transform infrared spectroscopy (FTIR) techniques.
 The results showed that all mixtures achieved the desired levels of strength for UHPC (150 MPa). Up to 28 days, the mixtures with RHA exhibited higher strength compared to those with FA, regardless of the curing type. However, at 91 days, the mixtures with FA and thermal curing were more resistant than the mixtures with RHA. Among the quaternary mixtures, at 7 days, the strengths of the mixtures were equivalent, indicating that FA did not react at earlier ages.