Bloating Mechanism of Lightweight Aggregate with the Size

Abstract

The purpose of this study was to investigate the bloating mechanism of artificial lightweight aggregates with different sizes (ESA, effective surface area). Aggregates were produced using hard clay, stone sludge, and a bloating agent in order to observe the effect of the gradation of the artificial lightweight aggregates. Kerosene and amorphous carbon were used as bloating agent. The particle size of the produced aggregate ranged from 3 mm to 9 mm. With regard to the amount of bloating agent to be used, 2 ~6 parts by weight were used. The specific gravity, absorption rate, and the type of aggregates produced by rapid sintering at 1075 ~1200 o C were determined. Microstructures were observed. When ESA had a value of 1 or below, kerosene, which has a high burning rate, was found to be advantageous for use as a bloating agent. When ESA had a value of 1 or above, carbon, which has a relatively low burning rate was found to be an advantageous bloating agent. It is thought that kerosene is more advantageous, as ESA decreases, for the production of aggregates having low water absorption rate.

Optimum conditions for unit processing of artificial lightweight aggregates using the Taguchi method

“…This is thought to be related to the viscous behavior of the aggregate; at higher temperatures, viscous behavior increases due to increases in the liquid phase. Lee et al [10] and Kang et al [13] also found that the aggregate density was lower at higher temperatures. The density decreased as the soaking time at the bloating activation temperature increased, but the density decreased after 10~20 minutes, with no significant difference between 20 and 40 minutes.…”

“…Studies of sintering variables have been conducted worked various methods. Different studies have investigated various sintering methods, including rapid sintering [10,11], two-step sintering [12], and normal sintering [1,13]. Riley [1] reported that most clays were expanded by rapid sintering, and defined the chemical composition for the production of lightweight aggregates through the normal sintering process.…”

“…Li et al [12] undertook two-stage sintering by dividing the dry section and the sintering section and then established the bloating conditions of lightweight aggregates with a bulk density of less than 1.0. Kang et al [13] obtained a lightweight aggregate with a low water absorption ratio and density level through normal sintering, and used the rapid sintering method in a study of lightweight aggregates with many types of waste added [10,11]. According to a report by Kaz'mina et al [14], it was confirmed that glass becomes bloated at a specific viscosity during the production of foamed glass, revealing that viscosity is an important aspect of bloating.…”

Thermochemical principles of the production of lightweight aggregates from waste coal bottom ash

“…74,75 A possible explanation for the reduction of hematite into wuestite (FeO) that could occur at a temperature range between 1100°C and 1160°C is the formation of liquid phase on the LWA surface that could hinder oxygen diffusion and create a reducing atmosphere in the LWA core, thus leading to hematite reduction. 7,76 In this study, the unburned carbon content for NV and WP ashes was small (0.12% and 0.19%, respectively), and complete oxidation of carbon in the form of CO 2 and CO release would happen at temperatures below 1000°C 29 (see Figures 5 and 6), which had some overlap with the temperature at which the liquid phase started to form (see Figure 3). This indicates that there could have been some contribution from Figure 15 presents a holistic view of each LWA to provide the required conditions (liquid phase quantity, viscosity value, and emitted gas amount) during sintering for successful production of spherical LWA.…”

Bloating Mechanism of Lightweight Aggregates due to Ramping Rate

“…ese various wastes were utilized, and various methods of sintering were used. Riley [14] and Kang and Kang [15] used a temperature elevation sintering method, and Lee [16,17] used rapid sintering. And the aggregate was sintered in the study of Lee [18] by the two-stage sintering method.…”