Flexible wall washing, also known as shotcrete facing, refers to spraying concrete onto a surface at high velocity. It produces a smooth final surface and is commonly used for architectural finishes and repairs. When applied to bridges, flexible wall washing provides an efficient approach to protect and beautify bridge structures.
Features and Benefits
Flexible wall washing has several significant advantages for bridge applications. Firstly, it forms an integral bond with the substrate, fully encapsulating the surface. This helps to seal and protect the underlying concrete. It also has high durability against weathering and chemical attacks from de-icing salts.
Secondly, flexible wall washing can be installed with no joints, creating a seamless finish. This minimizes leakage and infiltration, extending the service life of the bridge. The seamless coating also provides an attractive uniform appearance.
Thirdly, flexible wall washing is fast and economic. It can be applied rapidly with minimum traffic disruption. Labor costs are low since small crews can complete projects quickly. Little scaffolding or access equipment is required, reducing overall costs.
Application Procedures
Several steps are involved in applying flexible wall washing to bridges. First, the surface is cleaned and any spalls or damage patched and repaired. Next, a bonding agent is applied to the surface. Then the shotcrete is sprayed onto the surface at high pressure, typically using dry premixed concrete conveyed through hoses and pneumatically projected onto the surface at high velocity.
Multiple passes are made to build up to the required thickness. Finally, once the shotcrete has hardened, final finishing is performed. This includes smoothing the surface, sculpting details, and applying a paint or sealant system for aesthetics and protection. The entire installation process causes minimal disruption to traffic since most work is performed rapidly from below the bridge deck.
The Future of Flexible Wall Washing
Flexible wall washing is an innovative technology that enhances the preservation, durability, and appearance of concrete bridges. All concrete bridges will eventually require repairs and protection, so the future of flexible wall washing looks very promising.
Improvements in admixtures and aggregate gradations will produce shotcrete that is fiber-reinforced, self-compacting, and cures even faster. This will enable higher production rates, fewer lifts, and a superior surface quality with less finishing required. Developments in robotic spray arms may allow for the automated, unmanned application of shotcrete. This would further lower costs and reduce traffic impacts.
In summary, flexible wall washing is an advanced technique for protecting and enhancing concrete bridges. With its many benefits and promising future, it warrants consideration for applications in bridge projects worldwide. Continuous innovation will make it an even more competitive and sustainable solution.
