Mechanism and design of fluid catalytic cracking ash-blended cementitious composites for high performance printing

Abstract

As a common waste in the oil refinery industry, fluid catalytic cracking (FCC) ash is used to partially replace cement for high-performance high-speed 3D concrete printing (3DCP). Effects of FCC ash on hydration, rheology, and compressive strength were evaluated systematically, and the optimal substitution rate was determined as 20 wt. % of cement. A cylinder with 240 mm diameter and 500 mm height was successfully printed at a high speed of 100 mm/s with the optimal mixture in 5 min 53 s only. Moreover, the optimal mixture shows good leaching performance, and it also reduces CO2 emission by 21.45 % and materials’ cost by 17.98 % compared with the control. In addition to material optimization, the contributions of FCC ash to the early hydration and static yield stress were extensively analyzed. Complementary calorimetric and mineralogical investigations show that FCC ash accelerates the initial hydrolysis of cement and hydration of C3A and C3S. On the other hand, the quantitative analyses of static yield stress reveal the contributions of FCC ash on the colloidal force, volume fractions, particle size distribution, and ultimately static yield stress evolution. The developed 3D printable cementitious material possesses multiple advantages, including high-speed printing compatibility, enhanced sustainability, and high commercial values for oil refinery and construction industries. Based on the mineralogical property of FCC ash, the study also enlightens potential research and application of zeolite in 3D concrete printing in the future.