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1000 Year Concrete

The idea of extreme durability concrete is not all that new, but advancements in processing are making long-life concrete more cost-effective.

The key to extreme durability is tight particle packing and very low porosity resulting in dense, low permeability concrete with very low creep potential.

Self-Desiccating Concrete

Moisture-related flooring problems have become a thorn in the sides of many  architects, contractors, and building owners. The failures are typically caused by left-over batch water (known as water of convenience) or moisture vapor from the subgrade. Groundwater is rarely a significant factor. The excess moisture vapor mixed with highly sensitive (that is, water-tight) floor coverings creates a situation where flooring materials blister, bubble and delaminate entirely.

Composite Rebar

Non-corrosive and chemically inert, composite offers an alternative to traditional steel. The material does not have the same strength parameters as steel and cost is slightly higher. However, for aggressive environments it will long outlast steel reinforcing especially in bridges and roadways.

Ductile Concrete

Not satisfied with plain-old or even see-through concrete? Ductile concrete may be what you’re looking for. Composed of fiber reinforced concrete with precisely controlled particle sizes, the material is able to transfer loads to adjacent, unloaded areas without breaking. This unique material is perfect for high-seismicity zones, is extremely durable and impermeable, and is ideal as a repair material.

Translucent Concrete

Concrete is among the most versatile and rapidly evolving construction materials. Highly specialized structural applications are common; but in recent years more and more fascinating non-structural uses have come into the industry.

One such product is translucent concrete. If you ever wished your walls or ceilings could be see-through, here you go… The material works by batching parallel strands of optical fiber into the concrete.

Concrete Spheres Store Energy

MIT researchers are developing an energy generation and storage system that combines wind turbines with 100 foot diameter, hollow, concrete spheres. The ORES system would operate in waters deeper than 650 feet, much deeper than present-day wind turbines. These turbines would float and be anchored to the sea-floor by multiple concrete spheres. The concept works by using wind-power generated when demand is low to pump water out of the spheres. When demand peaks, hydrostatic pressure would push water through a turbine generating electric power.

Beware of Concrete Blowups!

Actually, this phenomenon is extremely rare. Failures such as these tend to be caused by incompressible debris collecting inside unsealed joints, thus restricting thermal expansion.

Generally speaking, the volume of a concrete is greatest when it is fresh and decreases over time. This is why we install control joints into slabs to deal with the inevitable random cracking.

For a given concrete, drying shrinkage is at least 5.0x10-4  up to over 8.0x10-4 ; whereas the typical coefficient of thermal expansion is 5.5x10-6 (ACI 224R-01).

Deicing Salts

As we head into fall, it's time to think about damage related to cold-weather conditions. One of the most severe and frequent in our climate is caused by deicers.
Contrary to claims that there are no “safe” compounds to control ice. Some compounds are less deleterious, but all can cause damage. Damage falls into two basic categories; scaling of young concrete and corrosion of unprotected reinforcing.

Tech Bulletin No. 6 - Hot-Weather Concrete Practice

Evaporation Rate Nomograph

In case you thought winter would never end—look out, summer is here!

With it comes a change in concrete practice. Temperature, humidity and wind create challenges to proper placement and curing.

The Evaporation Rate Nomograph (shown above) is a tool developed by the NRMCA in 1960 to combat rapid-drying problems such as plastic shrinkage cracking. The example line in light blue shows the steps and variables needed to determining evaporation rate.

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