Self-compacting, anti-washout underwater concrete for the marine foundations of the Constitución de 1812 Bridge over the Cadiz Bay

Abstract

Completion of the foundation for the marine towers required underwater casting of concrete to connect the bottom slab of marine caissons to their supporting piles. This concrete connection should guarantee water-tightness of the caissons and resist the negative pressures transmitted from the caisson to the piles. Structural and placing requirements for the underwater concrete were more demanding than that usually present for this kind of concrete, and included good bonding with connecting steel studs and rebars. This could be placed with standard pumping equipment and was able to fill the bottom slab cells from a single pouring point in an adjacent cell without showing significant washout, or suspension of solids silting in any point of the concrete surface.This article describes the design process and trials used to develop a self-compacting, anti-washout concrete mix meeting the project requirements.