Evaluation of the pozzolanic activity of heavy clay ceramic waste from main ceramic clusters of S. Paulo State, Brazil

To obtain technical, economic and environmental advantages, there has been an increasing interest in the cement industry for mineral additions partially substituting clinker in Portland cement. One of the most common mineral additions and that has been gaining ground in the Brazilian market consists of calcined clay, which basically adds the pozzolanic characteristics to their composite products. A material with properties similar to potentially calcined clays and not passed as pozzolan in the country refers to the residues of the ceramic industry (RCV). This study aimed to increase knowledge of the cementitious properties of RCV, focusing on the pozzolanic properties of eight samples collected in representative ceramic four major S. Paulo centers, Brazil, and its relations with the compositions of the raw materials used (ceramic material) and the firing temperature. The ceramic waste, after controlled milling, were suitable for use as an additive for pozzolanic Portland cement. The tested samples showed an average consumption of 500 mg of Ca(OH)₂/g of sample in the Chapelle test, surpassing by 14.7% the minimum standardized. The maximum observed reactivity is located in the firing temperature range between 700 °C and 800 °C. This interval corresponds to the usual higher reactivity burning levels practiced in red ceramic companies, which confirms the potential use of their waste as mineral admixture, causing the RCV can be a new source of pozzolanic material for cement sector in the country.

waste; red ceramic waste; pozzolan; Portland cement