Optimum mixing sequence and moisture content for hydrated lime fly ash bricks

The present study demonstrates the mixing process of lime stabilized fly ash bricks. In India, fly ash bricks are gaining popularity against fired clay bricks due to their green benefits. However, the lack of technical guidelines on mixing methodology, and disproportionate moisture content in raw materials adversely affect the performance and production of fly ash bricks. To mitigate this, dry and powdered form hydrated lime is suggested in place of slaked lime to avoid the excess moisture content. This study experimentally examines the combined effect of two distinct mixing sequences at five different moisture contents on the properties of hydrated lime fly ash (HLF) bricks. Compressive strength, dry bulk density, water absorption, percentage voids, dynamic modulus of elasticity, impact energy, and drying shrinkage were selected as the parameters for comparison of HLF bricks. Bricks with 15% moisture content produced by a two-stage mixing sequence were found to have enhanced mechanical and durability performance. Furthermore, economic and environmental comparisons (in terms of embodied energy and embodied carbon calculations) revealed that HLF bricks are more beneficial compared to fired clay bricks. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study shows that using hydrated lime instead of slaked lime and employing a two-stage mixing sequence to produce fly ash bricks with 15% moisture content can enhance mechanical and durability performance. Furthermore, economic and environmental comparisons indicate that hydrated lime fly ash bricks are more beneficial than fired clay bricks.