Development of Backfill Concrete Including Coal Gangue and Metakaolin and Prediction of Compressive Strength by Extreme Learning Machine

Abstract

The main aim of this investigation is to develop backfill concrete including coal gangue and metakaolin to reduce solid waste. For this purpose, a total of 30 concrete mixtures were designed by the inclusion of 0%, 25%, 50%, 75% and 100% coal gangue as coarse aggregates and 0%, 10% and 20% metakaolin as binder at 0.55 and 0.45 water to cement ratios. The compressive strength was tested after 3, 7 and 28 days for a total of 90 samples. Meanwhile, the influences of coal gangue and metakaolin on the elastic modulus, ultrasonic pulse velocity, rebound number and open porosity were explored. Then, the relationship between physical and mechanical properties was revealed by design code expressions and empirical models. Furthermore, an extreme learning machine was developed to predict compressive strength by concrete mixtures. The results show that the inclusion of coal gangue results in a poor performance in physical and mechanical properties of concrete. However, the drawbacks of concrete containing coal gangue can be compensated by metakaolin. The predicted results of design code expressions and empirical models are closed to the experiment results, with a 10% error. In addition, the findings reveal that the extreme learning machine offers significant potential to predict the compressive strength of concrete with high precision.

Experimental Research on Improving Activity of Calcinated Coal Gangue via Increasing Calcium Content

“…However, SCCG resources are limited, and most of the coal gangue stored in mining areas are non-spontaneous combustion coal gangues (NSCCGs). Currently, there are two main ways to utilize NSCCGs [ 5 , 12 , 13 , 14 , 15 , 16 ]. The first is to use it as a raw material for cement production; however, its poor homogeneity makes it unsuitable, which limits the wide utilization of NSCCGs in cement production.…”

Damage Model of Steel Fiber-Reinforced Coal Gangue Concrete under Freeze–Thaw Cycles Based on Weibull Distribution

“…Their study found that the proper incorporation of nano-silica could improve the impact resistance performance of steel fiber-reinforced concrete (SFC), and the impact damage factor of SFC satisfies the Weibull distribution. Jin et al (2022) explored the influences of different coal gangues and metakaolin on the mechanical properties of concrete. Their results showed a declined compressive strength of concrete with the incorporation of coal gangue and a boosted compressive strength of the concrete with metakaolin [15].…”

“…Jin et al (2022) explored the influences of different coal gangues and metakaolin on the mechanical properties of concrete. Their results showed a declined compressive strength of concrete with the incorporation of coal gangue and a boosted compressive strength of the concrete with metakaolin [15]. On the other hand, a certain volume of fiber is added to the concrete to mitigate the crack propagation in the concrete [16][17][18][19].…”