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Why Does Concrete Permeability Matter?


bridge using Houston ready mix concrete

Ensuring low permeability protects Houston ready mix concrete from early or unexpected degradation.

Concrete is the core of modern infrastructure, shaping everything from skyscrapers to sidewalks. It may seem as solid and sturdy as a rock, but there is a key characteristic that determines its lasting stability—permeability.

Permeability is the measure of a material’s capacity to allow fluids to flow through it. In concrete, this translates to the potential for water and any dissolved aggressive substances to seep through and affect the concrete’s integrity over time.

As a local concrete supplier, our goal is to provide you with a high-quality Houston ready mix concrete product that will maintain its integrity over the years.  For a concrete contractor you can trust, work with Texan Ready Mix Concrete for all your commercial and residential projects. Contact us today for a quote.

How Permeability Directly Affects Concrete Structures

There is a strong link between permeability and structural strength in concrete. Water soaking into concrete can affect both its physical structure and chemical makeup, compromising its durability. 

Chemically, the penetration of water facilitates the leaching of calcium hydroxide and other soluble substances from the concrete, weakening its structural integrity. When these substances are combined with oxygen, it can also speed up the corrosion of steel reinforcement inside the concrete.

In hot and humid climates like Houston, the constant exposure to moisture can cause expansion and contraction in the concrete as temperatures fluctuate, leading to cracking and spalling. This degradation process is exacerbated by the presence of salts and minerals in the water, which can precipitate and crystallize within these cracks, further widening them.

Concrete with a lower permeability is naturally more resistant to cracks, which is critical when it is used to create structures that have high structural and environmental stress, like bridge decks and seawalls. Low-permeability concrete can significantly prolong the lifespan of any structure, which reduces the need for frequent maintenance and repairs of Houston ready mix concrete.

Factors Influencing Permeability

Concrete’s permeability is affected by various factors, from mix design to construction methods. These include:

Water-Cement Ratio

The water-cement ratio in mix design is absolutely key. A lower ratio results in denser, less porous concrete, making it much less permeable. The water-cement ratio typically ranges from 0.40 to 0.60, depending on the concrete mix grade.

Aggregate Quality

The type and quality of aggregates used, such as the size and shape of the grains, can affect the concrete’s pore size distribution. The more uniform and smooth the aggregates, the lower the permeability of the final product. Crushed stone, gravel, and sand are the most common aggregates.

Proper Curing

The way concrete is cured during its early hardening phase affects its permeability. Effective curing, usually by keeping the right moisture levels, promotes the development of robust, long-lasting concrete with reduced permeability. Generally, this involves wetting the concrete multiple times per day for 7 to 14 days. Chloride ion penetration resistance significantly weakens when the curing time is less than 7 days.

Testing Concrete Permeability

Engineering standards and best practices rely on standard testing methodologies to assess the permeability of concrete. These are:

  • Rapid Chloride Permeability Test (RCPT): This non-destructive test method assesses how quickly chloride ions can pass through concrete. This measures its resistance to chlorides, which are a key contributor to steel rebar corrosion.
  • Water Absorption Test: By weighing a concrete sample and submerging it in water for a specified period, this evaluates the material’s propensity to absorb water.

High-Quality Ready Mix Concrete Supply in Houston

At Texan Ready Mix Concrete, we prioritize using high-quality materials and following best practices to produce low-permeability concrete that will stand the test of time. Trust us for all your ready mix concrete needs in the Houston area. 

Contact us for a quote and let us help you build with confidence

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