The expansion behaviour of concrete made of waste porcelain tile aggregates under elevated temperature

Advancing the circular economy of construction industry and waste porcelain tile resource utilisation are key to the sustainability of the sector. Existing research mainly focuses on the mechanical properties or durability of porcelain tile aggregate concrete, but little on its high-temperature thermal expansion behaviour. This gap impedes accurate assessment of its suitability for high-temperature applications, limiting its large-scale engineering use and resource value realisation. Therefore, the thermal expansion properties of porcelain tile aggregate concrete at elevated temperatures were studied. The concrete samples containing porcelain tile coarse and fine aggregates were prepared using a 50% mass replacement rate and a single-substitution mode. Testing was conducted at target temperatures of 200, 400, 600 and 800 °C using a high-temperature expansion testing system (heating rate: 10 °C/min), where thermal strains and coefficients of thermal expansion were measured during heating and holding phases. Differences in thermal expansion deformation before and after holding phase were analysed. The results indicated that the thermal strains and coefficient of thermal expansion of porcelain tile aggregate concrete increased continuously as heating duration prolonged and target temperatures increased. During the heating phase, a rapid increase in thermal strain was observed, whereas the increase rate gradually decelerated after entering the holding phase. Compared to normal concrete, porcelain tile aggregate concrete has significantly better thermal expansion performance – especially the coarse aggregate type. This benefit was particularly prominent at 800 °C, compared to normal concrete, its thermal strain was reduced by 21.7%, and coefficient of thermal expansion was reduced by 43.3%. After the holding phase, porcelain tile aggregate concrete experienced a notable rise in thermal strain together with a significant increase in coefficient of thermal expansion, whereas its thermal deformation rate showed a significant slowdown at high temperatures. This study elucidates the high-temperature thermal expansion behaviour of ceramic aggregate concrete, providing data for its application in refractory building structures and offering a new pathway for construction waste resource utilisation.