Using procelanite from phosphate waste as novel supplementary cementitious material

Abstract

Partial substitution of Portland cement with supplementary cementitious materials [SCMs] can reduce the CO2 emissions associated with concrete production. In this work, the use of a porcelanite as siliceous material, for the production of SCMs is evaluated. X-ray diffraction, x-ray fluorescence, and thermogravimetric analysis were carried out to characterize the porcelanite. After calcination, this porcelanite proved to be a material with multiple properties: it acted as pozzolan, with an optimal dosage between 6 % and 7 % by weight to maximize its performance. Cements incorporating this porcelanite demonstrated improvements in compressive strength of about 37 % and in flexural strength of about 13 %. These improvements were primarily due to the filling effect of finely ground grains and the pozzolanic reactivity, which allowed for densification of the cement matrix by generating C–S–H, the main contributor to strength. The addition of porcelanite significantly reduces cement soundness, while also accelerating setting. Tunisian porcelanite therefore represents a very promising SCM, provided its incorporation rate is well controlled [generally ≤10 %], offering a viable and sustainable solution for the construction industry.