Potential use of fly ash in structural fill application: a review.

Globally, over the years, fly ash (FA) has been successfully used in structural fills as a substitute for conventional infill material. As per the global industry trends and forecast report, the utilization rate of FA in 2021 was 74% in China, 65% in India, and 70% in the United States (US). Despite substantial research being done on the usage of FA as a substitute all over the world, only up to 15% by mass of total produce has been utilized as a replacement for infill soils. This indicates that there is a lot of potential for increased usage. From the view point of increasing the utilization rate, the present study focuses on summarizing the geotechnical properties of FA by taking strength characteristics into account as compared to conventional infill material. Moreover, this review underlines the chemical composition, index, and engineering properties. Firstly, it reviews the current state of the application of FA in structural fills by considering 141 articles that have been published since 2004 to till date. Secondly, it emphasizes the limited literature available on structural fill applications of FA. It also recommends the classification of FA besides the existing ASTM codes. Moreover, considering future research, this review also highlights the gaps in the previous studies, such as the need for amendments in existing standard codes for FA utilization as structural fill.

Structural Performance of Ferrocement Panels under Low- and High-Velocity Impact Load.

The primary objective of this experimental study is to examine the response and energy absorption capacity of ferrocement panels exposed to low- and high-velocity impact loads. The panels are reinforced with two different types of mesh layers, namely, welded wire grid (WWG) and expanded wire grid (EWG), with varying percentages of steel fibers (SF). The ferrocement panel system is made up of cement mortar reinforced with 0-2% SF with an increment of 1% and wire grid layers arranged in three different layers 1, 2, and 3. A consistent water-cement ratio (w/c) of 0.4 is maintained during mortar preparation, and all panels are subjected to a 28-day curing process in water. The study utilized square-shaped ferrocement panels measuring 290 mm × 290 mm × 50 mm. The panels are exposed to repeated impact blows from a 2.5 kg falling mass dropped from a height of 0.80 m. The count of blows necessary to commence the first crack formation and the cause of ultimate failure are recorded for each panel. The study reports that an increase in SF content and the number of wire grid layers increased the number of blows needed for both the first crack and the ultimate failure. In the high-velocity impact test, 7.62 mm bullets are fired at the panels from a distance of 10 m with a striking velocity of 715 m/s. The study observed and analyzed the extent of spalling, scabbing, and perforation. The results showed that an increase in fiber content and the number of wire grid layers led to a decrease in the area of scabbing and spalling compared with the control specimens. It was also possible to see the mode of failure and crack pattern for impacts with low and high velocities.