Through a Change Proposal by Facca Incorporated, the Ontario Ministry of Transportation (MTO) approved the replacement of the as-tendered steel H-piles by newly designed prestressed/precast Ultra-High-Performance Concrete (UHPC) piles for supporting the west abutment of the Lily River Detour Bridge. The 300 mm (~12”) deep UHPC piles were designed and installed at the west abutment based on the previous successful development and testing of a tapered H-shaped pile at Iowa State University. The east abutment, as tendered, was designed to be supported by six steel H-shaped battered piles driven to bedrock. For the west abutment, six UHPC piles were produced and installed using the same batter. Since the site contained occasional boulders and the design intent to drive the piles to bedrock, the UHPC piles were fitted with steel shoes for the first time. All piles were successfully installed to reach the targeted load bearing capacities. After the replacement bridge was constructed, the detour bridge was removed and the UHPC piles were extracted to examine the conditions of the piles. This presentation will provide details of the innovative design of the piles, fabrication and driving of the piles, and lessons learned from analyzing the driving data and removal of the piles. Fellowship and Scholarship recipients. With the help of generous donors from the concrete community, the ACI Foundation awards high-potential undergraduate and graduate students in engineering, construction management, and other appropriate curricula.

As the worldwide availability of natural sand for concrete continues to decline, attention has turned to manufactured sand obtained from coarse aggregates as an alternative. However, there is still limited information regarding its use in concrete mixtures beyond adhering to standard particle gradation bounds (e.g., CSA A23.1 bounds in Canada). To address the gap, this study presents a central composite design of experiments to analyze the influence of mix proportions on the packing density of concrete mixtures incorporating four types of aggregates: 2 mm sand and manufactured sand, 5-14 mm and 10-20 mm coarse aggregates. The packing density was measured using an intensive compaction tester and results were analyzed using a response surface methodology. The study also included four optimized mix designs obtained using the Fuller-Thompson and the Funk and Dinger methods. Results indicate that a higher proportion of manufactured sand and a higher packing density can be achieved with a particle gradation having a higher proportion of smaller-sized particles. Moreover, the TFA/TA (total fine aggregates/total aggregates) ratio significantly influenced the packing density, whereas the impact of the ratio of 5–14 mm/total coarse aggregates (TCA) was minimal. A prediction model for packing density was developed using multiple regression analysis. These findings provide information on how manufactured sand affects the packing density, which can serve as a foundation for designing concrete mixtures with manufactured sand.

The 2019 Edition of ACI 318 introduced several key changes to the one-way and two-way shear design of slabs. Chapter 22 introduced a size effect for the one-way and two-way shear strength of concrete for slabs either without or with shear reinforcement. ACI 318-19 also introduced a revised version of the Vc equation for one-way shear that included the effect of the member flexural reinforcement ratio. Chapter 8 of ACI 318-19 also introduced new minimum flexural reinforcement requirements to prevent premature punching failure of lightly-reinforced above grade two-way slabs and to promote instead a flexure-driven type of response. In ACI 318-19, recognition of the size effect is required for above grade slabs only and not for shallow footings or foundation mats. The Code is silent on whether the new Chapter 8 minimum flexural reinforcement requirements for slabs apply to spread footings.

This paper examines the reasons for the differences in size effect requirements between slabs and footings. It also evaluates the applicability and the impact that the new Vc equation for one-way shear has on the shear strength of isolated or continuous footings and whether the new flexural reinforcement requirements of Chapter 8 can be extended to spread footings. It also suggests a design recommendation to acknowledge the beneficial effect that compact footing dimensions can have on punching strength.

The present paper describes the building of the Fourth Bridge on the Grand Canal in Venice, designed by the Architect Santiago Calatrava. In particular, this paper is devoted to the laboratory and field tests to develop the composition of a self-compacting concrete (SCC) to be placed in the congested reinforced foundations of the Calatrava Bridge. To ensure a durable service life of at least 100 years, a water-cement ratio as low as 0.45 was adopted due to the contact of the reinforced foundations with the seawater. The placement of the SCC was carried out in only a few hours of a night to reduce the interruption of the ferry traffic in the Grand Canal. The concrete was pumped from truck mixers, all located on the Rome Square side of the bank of the Grand Canal, and feeding the fresh mixture in both the reinforced spaces devoted to the foundations. The reinforced foundations are exposed to a significant load due to the heavy weight of the bridge manufactured of steel and glass, as well as to the shear stress caused by the peculiar shape of the bridge characterized by a segmental arch. Due to these factors, some cracks were observed every year on the top of the foundations. This means that in the next future some measures should be taken to block the formation of new cracks. Meanwhile, the already formed cracks have been sealed and protected by an upper coating stone in order to inhibit the ingress of the airborne swept by the wind from the close sea water causing the corrosion of the metallic reinforcements promoted by the presence of chloride ions.

The conservation state of foundation piles of highway viaducts close to a train line was investigated with a visual inspection, laboratory tests on the cementitious material and electrochemical monitoring, as well as galvanostatic pulse measurements for the steel parts. Each viaduct pile had 10 to 15 foundation piles inserted into the ground to a depth down to 15 meters. Two main types of piles were observed. Reinforced concrete piles and steel piles were embedded internally and externally in the cementitious material. The results indicated the absence of significant corrosion of the metals in the upper part of the piles. This was also due to poor carbonation in the ground. Along a viaduct, the presence of chloride in the groundwater increased the risk of corrosion, although it did not reach the steel parts yet. The monitoring of the stray currents did not exhibit a relevant shift in the anodic direction of the steel corrosion potential, thus indicating a reduced corrosion risk. The galvanostatic pulse measurements showed some possible local corrosion issues that may arise, especially with depth. This also depended on the formation of macroelements along the piles. Nevertheless, this latter problem may be reduced due to the higher presence of humidity and the oxygen depletion with depth.