Reactive Powder Concrete Containing Fly Ash: Mixing Technique Effects and Mechanical Properties

Abstract

This study explores the development of reactive powder concrete (RPC), which is known for its high mechanical properties and durability beyond conventional concrete. RPC has a unique composition including cement, silica fume, fine sand, superplasticizer, water and steel fibers. However, its performance is greatly affected by factors such as ingredient selection, mixing method and curing technology. Fly ash is a by-product of coal combustion and has the potential to serve as a partial cement replacement, enhancing the performance of RPC while reducing cost and environmental impact. However, the challenges of blending RPC, especially those with low water-to-cement ratios, remain significant and research on the mechanical properties of RPC containing fly ash is still limited.

This study aimed to (1) evaluate suitable mixing techniques for fly ash-containing RPC and (2) analyze their mechanical properties under selected mixing methods. Single-batch and double-batch techniques were studied, as well as the effects of single- and mixed-size steel fibers and different mixing temperatures. Double batching has been shown to significantly improve performance, mixed size fibers improve compressive strength, and single size fibers increase flow. However, high mixing temperatures reduce workability. The compressive strength, splitting tensile strength, and flexural strength of RPC containing fly ash were evaluated under double batches and compared with the ACI 318 standard and relevant literature.

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