Behaviour of concrete made with waste porcelain and silica fume

The demand for natural aggregates has increased with the fast-expanding construction activities and urban development. Meanwhile, significant amounts of waste porcelain, which are the result of construction, demolition, and production, are readily dumped in landfills even though they can be reused. The utilisation of waste aggregates in concrete, however, may be challenging because their physical and mechanical properties differ from those of natural aggregates. Producing concrete with potential environmental benefits by utilising waste materials, while, maintaining its desirable characteristics is an essential issue. This research mainly examined the combined effect of substituting the coarse natural aggregate (NA) with discarded tiles waste porcelain (WP) at multiple ratios, including 30%, 50% and 100%, along with cement partial replacement with silica fume (SF) at 0%, 10% and 20%. Ten concrete mixes, the first of which is control, were tested in terms of fresh-concrete consistency and hardened characteristics, including mechanical strengths, impact energy and abrasion resistance. For every mix, the same experimental programme was employed. The concrete mixes were designed to achieve a target mean 28-day compressive strength of 40 MPa. The absolute-volume method was utilised in the calculation of mixture proportions while maintaining a constant total mix volume, in addition to keeping a water-binder (w/b) ratio at 0.45, but the batch water was adjusted based on the moisture states and absorption of each aggregate fraction, and no superplasticiser was added. The results generally showed that the incorporation of WP individually as well as in combination with SF adversely affects concrete slump values, especially with high dosage replacements. The same adverse effect was noticed on concrete strengths when only WP substituted NA at all levels; the decline in strengths was statistically significant, especially at the 100% replacement level. The 10% SF inclusion slightly enhanced concrete strengths; further increasing of SF dosage to 20% resulted in extra strength gain and surpassing the control in M8 with (3.76%) in compressive strength and (1.08%) in splitting tensile; however, the difference was not statistically significant ( p > 0.05). A statistically significant improvement was observed ( p < 0.05) in the M8 results, with an increase of 8.28% in flexural strength, 18.91% in impact energy resistance, and 30.61% less weight loss in abrasion. Beyond this point, when WP replacement levels increased, keeping 20% SF, the results showed a declining trend. In conclusion, the combined effect using 30% WP and 20% SF revealed a promising approach for producing a waste-material-based concrete for application that requires relatively higher mechanical characteristics and favourable impact resistance and abrasion resistance. However, careful consideration must be given to the used materials’ properties and production quality control.