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.

The present paper shows the study of a mixture design of the concrete used in the reinforced foundations of the bridge on the Straits of Messina in Italy. A cube compressive characteristic strength of 35 MPa (5,075 psi) is required for the foundation concrete. Due to the peculiar shape of the concrete foundations (completely embedded in the excavated ground), the damages caused by the thermal stress, the steel corrosion, and the alkali-silica reaction cannot be monitored and repaired. Therefore, a concrete structure must be designed without any damage for at least 200 years due to the very important role of this structure from a social point of view. In order to guarantee this long-term durability, there are two problems to be faced and solved: 1) the heat of cement hydration could cause cracks inside the foundation due to thermal gradients between the hotter nucleus of the massive structure and the colder peripheral areas; 2) the corrosion of the metallic reinforcements caused by the reaction between the metallic iron and the oxygen (O₂) present in the air to an extent of about 20%; 3) the alkali-silica reaction causing a local disruption in the concrete. All these problems can be solved using a blast-furnace slag cement such as CEM III B 32.5 R characterized by a very small heat of hydration and adopting a ground coarse aggregate with a maximum size as large as 32 mm (1.28 in): the choice of this aggregate produces a reduction in the amount of mixing water and then of the cement content and reduces the volume of the entrapped air at about 1.3% by concrete volume. This amount of O₂ would cause the corrosion of a negligible amount of iron corresponding to only 10 to 13 g (0.4 to 0.5 oz) of steel in 1 m³ (1.31 yd³) of concrete of each foundation. In order to prevent any ingress of air from the environment, the top of the foundation should be protected by self-compacting, self-compressing, and self-curing concrete.

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.

Radon is a radioactive invisible, odorless, tasteless gas that seeps up through the ground and diffuses into the air. Radon gas naturally moves into the permeable soil and gravel bed surrounding foundations and then, inside the buildings through openings, cracks, and pores of the concrete. The type of constructions more exposed to the radon risk emanated from the ground are industrial buildings, supermarkets, shops, restaurants, and all the residential buildings where people work or live on the ground floors. In the present paper, the rehabilitation of building polluted by radon gas has been studied. Two techniques can be adopted to reduce the radon concentration in the building environments: A) change of the environmental air opening doors and windows of the building; B) if the change of air is incompatible with the industrial activity carried out in the building the radon entry can be blocked using the application on the existing concrete surface of a specific cap sheet membrane; in particular a bitumen-based radon gas barrier has been examined already studied and acting as an effective radon gas barrier. In the end, the radon barrier can be covered by a concrete layer. According to the Italian Legislative Decree No. 101/2020 presently the radioactivity caused by the radon gas in the houses and industrial buildings must be lower than 300 Bq/m³, whereas for the building erected after December 31, 2024, should be lower than 200 Bq/m³.

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.