When looking to obtain the biggest bang for your concrete buck, you can’t go wrong with post tension technology. From a simple slab on ground project to the construction of a complex system of freeway interchanges, post tensioning your concrete elements can provide superior strength with less material.
THE POWER OF COMPRESSIVE FORCE
Tensioning your concrete grants it the ability to better counter expected service loads by way of internal compressive force. A great way to envision the compressive forces of post tensioning is to imagine moving several wood boards from one place to another. You could stack them and allow gravity to hold them together as you pick them up, or you could clamp them horizontally until the force of compression holds them together for vertical lifting.
POST TENSION AND PRE-STRESSING: CONCRETE CONCEPTS THAT WORK
Two methods serve the purpose of adding internal tension to a concrete structure depending on the site of fabrication.
PRE-STRESSING
This method works well if the concrete is pre-fabricated and brought to the site for positioning. Steel tendons are tensioned prior to the pour. Once the concrete, poured into form around the tendons, has reached the required strength, the tension is released and the tendons act to regain their original length which creates the effect of pulling the outer concrete towards the center.
POST TENSIONING
If the construction design calls for on-site concrete pouring, technicians place plastic or thin-walled metal tubes in a parabolic (wavy or curved) pattern around which the concrete is poured. The steel tendons are then run through the tubes and mechanically pulled until stretched about eight inches in a hundred feet, at which point they are anchored to the outer edge of the slab, compressing it inward as the tendons try to return to their former lengths.
TAKING ADVANTAGE OF POST TENSION TECHNIQUES IN COLORADO CONSTRUCTION
Post tensioning concrete works well everywhere with almost no disadvantages. In fact, the potential for corrosion, present with any non-stainless steel product, comprises the bulk of any drawback. Since grease and encapsulated anchors can inhibit rust on channeled tendons, using pre-stressed or post tension concrete affords many benefits with no real shortcomings.
1. EXPANSIVE SOILS
Colorado, as a proud member of the Southwestern states, hosts expanding or shifting soils in many areas which can wreak havoc on foundations and roads. However, by using post tension concrete, unstable ground poses far less of a threat to your projects than other concrete systems.
2. SEISMIC ACTIVITY
While Colorado has experienced few strong earthquakes for eons, an active fault line stretches the length of the front range and can produce a tremor from time to time. Pre-stressed and post tensioned concrete have both the compressive and tensile strength to better maintain cohesion during earthquakes.
3. LONGER SPANS AND THINNER SLABS
Tensioned concrete enjoys greater durability and overall strength than normal reinforced concrete. You can design longer unsupported spans with thinner pours. This makes it great for auditoriums, parking garages, bridges, roofs and custom architectural designs.
4. FEWER JOINTS
Because the internal compressive force holds the concrete together better than rebar alone, it reduces shrinking. Joints can be fewer and farther between. Furthermore, any cracks that develop tend to be held tight. This helps prevent the water intrusion that can decompose concrete through Colorado’s yearly freeze-thaw cycles.
5. USE LESS MATERIAL
Post tensioning means less concrete and rebar must be used to obtain the same strength and durability. You may need only 80 percent of the concrete and only 25 to 40 percent of the rebar otherwise essential for your project. While post tensioning does require special technicians to properly engineer and install the steel tendons, the cost can be offset by the reduction in material costs.
6. FASTER CONSTRUCTION
Needless to say, if you use less material, you can also shorten your building timeline.
WHO OFFERS POST TENSION EXPERTISE IN COLORADO?
Pre-stressing and post tensioning involve specifically trained, certified and experienced personnel. This is not something that can be accomplished by an ordinary concrete crew. Barton Supply provides not only the necessary post tension products, but also the expertise and on-site service. Please call us for more information about post tension concrete construction.