Experimental study demonstrates aggregate floating dynamics govern concrete homogeneity, indicating paste and density control yields high specific strength.
Key Points
To quantitatively evaluate the floating behavior of lightweight aggregates in fresh concrete and determine its mechanisms and effects on hardened mechanical performance.
Quantified aggregate floating and uniformity using the floating index (FI) and coefficient of variation (CV) across varying aggregate characteristics and paste parameters.
Modeled floating kinetics and characterized microstructural changes using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM).
Aggregate floating was predominantly governed by particle size, density differences, and paste viscosity, with higher water-to-binder ratios increasing segregation while an OPC-FA-G binder system optimized spatial uniformity.
Increasing lightweight aggregate cylinder strength boosted the 28-day concrete compressive strength from 23.0 MPa to 59.5 MPa.
Floating index correlated strongly with specific strength (r = -0.94), enabling the optimized concrete to achieve superior specific strengths of 25 to 33 MPa·m³/t.