Bloating Mechanism of Lightweight Aggregates due to Ramping Rate

The purpose of this study was to improve the recycling rate of industrial wastes by investigating the bloating mechanism of artificial lightweight aggregate depending on the ramping rate and time, which is a dynamic parameter in the production of artificial lightweight aggregate. In this study, coal bottom ash and dredged soil at a weight ratio of 1: 1 from a domestic power plant were used as raw materials. The artificial lightweight aggregates were formed by using an extruder and pelletizer (φ = 10 mm) and sintered by rapid sintering, 2-step firing, and normal sintering method. The physical properties of the aggregates such as bulk density, water absorption ratio, and microstructure of cross section are investigated with the sintering time and temperature. As the result of bloating and trapping mechanism, black core could be inhibited as the firing time increased at the temperature before surface formation. As a result of firing schedule graphs using least square method, it was possible to manufacture artificial lightweight aggregate with micropores, specific gravity of 1.1, and absorption rate of 3% at a heating rate of 27°c/min or less.