Reuse of kaolinitic waste as a precursor of pozzolanic material

Influence of grinding of calcined kaolinitic waste on the properties of cement pastes

“…For the compressive strength test, cylindrical specimens of 2.5 cm in diameter and 5 cm in height were molded and cured for 3 and 28 days. It was observed that during calcination there was an agglomeration of particles, as there was a significant increase in D 50 in relation to that of KW, which was 3 μm, as determined by [6], this agglomeration also occurred with Lima [26] and Huang [27]. Therefore, a study of the grinding was made and the time required to obtain a material with a smaller size was determined, as shown in Figure 1 and Figure 2.…”

“…KW was calcined at 700°C, the final temperature was maintained for 90 min, conditions defined as ideal by [6]. The calcined kaolinitic waste (CKW) was then characterized, the density was obtained through a gas pycnometer (AccuPyc 1340, Micromeritics), the particle size distribution of PC and CKW particles was determined in a laser particle sizer (Mastersizer 2000, Malvern).…”

“…Afterwards the temperature was raised to 1000°C at a heating rate of 10°C/min. To compare the results between pastes of different compositions, mass losses and other calculated parameters were obtained from TG / DTG curves based on the initial cement mass [24] as detailed in [6] TM-1000 Hitachi SEM was conducted to investigate the micro-morphological structure of the paste samples cured for 3 and 28 days. Nitrogen adsorption analysis (ASAP 2020 equipment Micromeritics) served as pore size distribution measurement of hardened pastes with 28 days of hydration.…”

“…One of the most effective and promising approaches is the use of solid waste as mineral additions in Portland cement to partially replace it. Previous studies have shown that cement with these materials shows improved hydration, good mechanical properties and increased durability [5][6][7][8][9][10][11] The beneficiation of kaolin, which has as its main destination the paper industry, generates, of its gross production, 26% of a waste that is deposited in ponds, thus becoming a financial and environmental problem. This waste is rich in kaolinite and has low quartz content, and thus can be a raw material to produce highly reactive metakaolinite [12].…”