Abstract: Evaluating Concrete Compaction: A Multi-modal Approach

Concrete compaction quality is crucial for structural strength and durability, as entrapped pores weaken concrete while segregation risks uneven material distribution. Hassan Ahmed at Aalto University analyzed compaction effectiveness by measuring segregation and pore distribution in fresh and hardened concrete. Using AC-impedance spectroscopy (ACIS), the study introduced a segregation index that evaluates aggregate segregation in fresh concrete. For hardened concrete, indices based on density and aggregate distribution quantified segregation levels, revealing variations across vibration durations and mix consistencies. Additionally, X-ray tomography was used to examine entrapped pores, showing that longer compaction times effectively reduce porosity in low-workability concretes while posing segregation risks for high-workability mixes. Traditional indicators, like observing bubble emergence to the surface, proved unreliable, highlighting the need for advanced, objective monitoring techniques. Findings suggest that incorporating real-time monitoring and the new segregation indices can optimize concrete quality by balancing air expulsion and minimizing segregation. Future research aims to refine ACIS monitoring and explore smartphone-compatible on-site tools, contributing to improved construction practices and potentially reducing environmental impact.

The doctoral thesis can be read here: https://aaltodoc.aalto.fi/items/44d99e5e-1238-4392-892d-243aecea4427

Read the entire article in Finnish and see the images >>