This paper presents a method for simply qualifying the practical risk of casting deep foundations based upon a combination of the behavior of the fresh concrete through testing and the confinement conditions of the foundation from a design perspective. A framework to qualify which aspects of the tremie process lead to defects is developed for the first time. Flow behavior, confinement conditions, and free-water availability are identified as key contributors to specific defects present within tremie concrete foundations. Finally, a novel risk map for tremie concrete is presented.

Despite improvements in nondestructive testing (NDT) technologies, the quality assurance of concrete reinforcing bar (rebar) placement is still primarily conducted with conventional methodologies, which can be time-consuming, ineffective, and damaging to the concrete components. This study investigated the performance of two commercially available cover meters and one ground penetrating radar (GPR) device. A cover meter was found to have the greatest accuracy for depths smaller than 3.19 in. (81.0 mm), while the GPR performed better for greater depths. The effect of reinforcing bar depth, diameter, and type; neighboring reinforcing bar; and concrete conditioning on the performance of the devices was quantified. The use of epoxy-coated reinforcing bar, galvanized reinforcing bar, and stainless-steel reinforcing bar was found to have a negligible effect on cover meter accuracy. A model was developed to predict the precision of the GPR post-measurement analysis given a depth and concrete dielectric constant.

Pumping of air-entrained concrete can result in variable air content, which leads to possibly rejected concrete. This research used air volume, super air meter (SAM) number (AASHTO T 395), bulk freezing and thawing (ASTM C666/C666M), and hardened air-void analysis (ASTM C457/C457M) to investigate the air-void quality and freezing-and-thawing durability performance of concrete before and after pumping. The laboratory results show that the fresh-air testing measurements after pumping fresh concrete are not accurate indicators of the freezing-and-thawing resistance based on the hardened air-void analysis. However, testing fresh concrete prior to pumping is a better indicator of the freezing-and-thawing performance.

Determining the in-place properties of mass concrete placements is elusive, and currently there are minimal to no test methods available that are both predictive and a direct measurement of mechanical properties. This paper presents a three-stage testing framework that uses common laboratory equipment and laboratory scale specimens to quantify thermal and mechanical properties of mass high-strength concrete placements. To evaluate this framework, four mass placements of varying sizes and insulations were cast, and temperature histories were measured at several locations within each placement, where maximum temperatures of 107 to 119°C (225 to 246°F) were recorded. The laboratory curing protocols were then developed using this mass placement temperature data and the three-stage testing framework to cure laboratory specimens to represent each mass placement. Laboratory curing protocols developed for center and intermediate regions of the mass placements reasonably replicated thermal histories of the mass placements, while the first stage of the three-stage framework reasonably replicated temperatures near the edge of the mass placements. Additionally, there were statistically significant relationships detected between calibration variables used to develop laboratory curing protocols and measured compressive strength. Overall, the proposed three-stage testing framework is a measurable step toward creating a predictive laboratory curing protocol by accounting for the mixture characteristics of thermomechanical properties of high-strength concretes.

The use of construction waste to prepare recycled micro powder can improve the use of construction waste resources and effectively reduce carbon emissions. In this paper, researchers used waste concrete processing micro powder to prepare foam concrete (FC) and quantitatively characterized the performance and pore structure of FC by scanning electron microscopy (SEM), pore and fissure image recognition and analysis system (PCAS), and mechanical property testing methods with different mixing ratios of micro powder. The results showed that the effect of single mixing of micro powder or fly ash is better than the composite mixing test, and the optimal proportion of compressive strength of single mixing of micro powder is higher than that of single mixing of fly ash. The optimum mixing ratio is 6:4 between cement and micro powder, and the best effect is achieved when the micro powder mixing amount is 40%. Single or double mixing can fill the pores between the foam and strengthen the performance of the substrate. The tests of single-mixed or compound-mixed micro powder showed that the fractal dimension decreased with the increase of porosity; when the fractal dimension of the specimen increased, the average shape factor became smaller, the compressive strength decreased, and the water absorption rate increased.