Utilization of ceramic tile demolition waste as supplementary cementitious material: An early-age investigation

Construction and demolition (C&D) activities generate large amounts of waste, such as ceramic tile demolition waste (CTDW). However, the recycling ratio of C&D waste is generally of 3-10%. In this work, pastes with 0-30 wt% replacement of Portland cement by CTDW and limestone (reference filler) were produced. The particle packing, fresh-state properties (mini slump and rheometry), cement hydration (isothermal calorimetry and in situ X-ray diffraction - XRD) and compressive strength of the pastes were evaluated. The results showed that CTDW incorporation reduced the inter particle distance of the system while limestone increased it. Consequently, CTDW incorporation progressively increased the static yield stress and viscosity of paste while reducing the mini slump. CTDW enhanced the cement hydration kinetics compared with limestone, increasing the main heat flow peak, 24- and 168-h cumulative heat values by up to 8%, 5% and 6%, respectively, for the same incorporation level. Furthermore, in situ XRD and calorimetry indicated equivalent hydration for CTDW and limestone incorporation up to 8 h, from which the residue led to further alite consumption and hydrates formation (i.e. ettringite and portlandite). Compressive strength results at 1 and 7 days had good agreement with the cumulative heat values, indicating that CTDW led to strengths up to 5% higher than limestone did for the same replacement level and age. No significant pozzolanic reaction by CTDW was observed up to 7 days.