MECHANISTIC ROLLER-COMPACTED CONCRETE MIXTURE DESIGN AND
TEST METHODS FOR CONSTRUCTABILITY AND SUSTAINABILITY
Advisor: Jeffery R. Roesler
Abstract:
Current roller-compacted concrete (RCC) pavement mix design procedures do not directly integrate aggregate properties and require specialized experience to select and proportion constituents to achieve constructability, strength, and sustainability targets. Standard field and laboratory test methods do not reliably evaluate RCC constructability, which forces costly trial and error mix development and field test strips. The rational selection of RCC mixture constituents and proportions corresponding relation to pavement constructability needs significant advances for broader RCC quality and adoption.
To achieve this goal, the theoretical optimal paste volume model was first used to define RCC volumetric relationships between material constituents such as underfilled, equifilled, and overfilled aggregate voids with paste. A laboratory testing protocol was subsequently developed using the gyratory compactor to evaluate RCC mixture constructability with volumetric energy, shear strength, and paste mobility. Aggregate morphology, paste content, paste rheology, and binder composition were factors tested in the laboratory to connect material selection to performance. Additionally, several RCC paving projects were visited to calibrate laboratory performance parameters with field constructability and to determine key RCC volumetric parameters such as intergranular volume of voids (IGV), total paste volume (TPV), ratio of voids filled by paste (VFP), specific surface area (SSA), effective paste film thickness (EPFT), and water-to-cement ratio (W/C). EPFT values between 1 and 11 µm were found to be the most significant parameter for overall constructability, strength, and sustainability.
Finally, this research has proposed a mechanistic mix design framework that guides designers into selecting RCC constituents and aggregate proportions, initial mix proportions from the laboratory volumetric parameters, a method to quantify constructability in the laboratory, quality control tests in the field, and smart adjustments for underperforming mixtures.