Brief
Water is a necessary component in the creation of concrete, but the ideal moisture content is critical to ensuring strength and durability. Tanzin Fatima and Roy Cannon of Pecora Corp. write about the problems and challenges of internal moisture in concrete and the various ins and outs of understanding moisture content and how it affects concrete.
Insight
An approximately 2,000-year-old technology, concrete is used as a structural component in commercial/ residential buildings, pavements, and driving surfaces of bridges and roads.
From earlier use in the Great Pyramids at Giza and the Great Wall of China to modern 3D Printed buildings, concrete is currently being utilized due to its longevity, versatility, strength, durability, in-service energy efficiency, resilience, and economical benefits compared to other masonry composites and/or building materials. However, concrete is not maintenance-free.
Moisture is one of the major concrete system enemies.
Water, the lifeblood of concrete is its best friend and worst enemy. Moisture sources and presence in concrete systems could be both external and internal.
Since internal sources of moisture in concrete structures mostly lead to ultimate coating failures, including during application and long-term durability, the goal is to concentrate on the latter (internal) water source.
Problems & Challenges of Internal Concrete Moisture
Modern concrete is a product of a chemical reaction between mixtures of cement binder, water, sand aggregate, and various additives.
While water is a necessary and critical component in concrete mix formulas and is needed to ensure strength and durability, inaccurate water concentrations may be the source of poor concrete performance. A higher water-cement ratio (increase in the water content in concrete) tends to make weaker, more permeable, and less durable finished concrete structures
The second influence of internal concrete moisture is associated with the curing process and the speed of drying at the concrete surface.
Excessive water evaporation at the concrete surface can lead to some significant problems in the application of coatings, including adhesive failure, blistering, discoloration, bubbles/pop-outs, cracks, delamination, efflorescence, mildew/ mold development, etc. These are the results of a water-starved concrete surface reaction leading to weak and substandard surface cures
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