Post Tensioning: An Engineered Solution
Post-tensioning utilizes concrete’s inherent compressive strength to construct slab-on-ground foundations
that require a reduced volume of concrete and can be less costly. Concrete is exceptionally strong
in compression, but weak in tension. By introducing an external compressive force from the post-tensioned reinforcement into the concrete before the foundation experiences soil induced movements, the concrete becomes more resistant to tensile stresses that tend to pull it apart and cause it to crack.
As opposed to conventional reinforcements or wire mesh, post-tensioning is an active reinforcement
that applies an external load prior to soil induced movements being applied. In unbonded post-tension
construction, the tendons are placed prior to concrete placement and once the concrete has reached a
specific initial compressive strength, the tendons are stressed to a specified force and anchored. The
compressive force is imparted into the concrete through anchorage assemblies attached to each end of
A post-tentioned concrete slab-on-ground foundation is an engineered solution that provides significant
advantages over other reinforcement systems. Post-tension reinforced foundation systems fit most all soil conditions from stable sites to highly expansive sites. Any foundation application can use a post-tensioned reinforcement system. Single-family residences, industrial floors, sports courts, apartment buildings, and many other project types will benefit from a post-tensioned solution from Kustom Krete Post-Tension.
The Wafflemat is a green product made from 100% recycled polypropylene plastics. Because the wafflemat boxes are voided there is less concrete volume used in a Wafflemat foundation. This concrete displacement leads to a reduction in CO2 emissions, and a potential savings in material costs.
The Wafflemat foundation forming system creates a new type of post-tensioned foundation system, only available from Kustom Krete Post-Tension. It offers the ease of construction of a Uniform Thickness Foundation along with the material efficiency of a Ribbed Foundation. The Wafflemat, which has been in use since 1995, has been used in more than 7 million square feet of residential living space. Interlocking bottomless plastic boxes create the waffle design. The waffle box sits on the prepared soil and connects to three other boxes to create a unit of approximately 44-inches. These units are evenly spaced throughout the foundation. The spaces between the units form the ribs of the foundation from which it derives the stiffness that prevents the foundation from bending. No trenches or dug footings are necessary in a Wafflemat foundation.
Savings in foundation installation time can be realized with the Kustom Krete Post-Tension Wafflemat foundation forming system by elimination the trenching and spoil disposal necessary in an earth-formed system.
The builder will appreciate the time savings and associated cost-savings that are realized with the Wafflemat. By using a plastic form, in lieu of an earth-formed ribbed foundation, concrete volumes are closer to estimated quantities, reducing material waste and unnecessary placing labor. The variability in slab thickness and rib dimensions, often seen in earth-formed applications, can be also eliminated with the Wafflemat.
Kustom Krete Post-Tension understands the value of quality engineering performed by experienced professionals. Because engineering is such an essential part of the service that we provide, Kustom Krete employs 15 Professional engineers and more than 100 P/T technicians. Our engineering groups recognize the importance of an engineered design that is both economical and constructible.
Our post-tension technicians work under the supervision of licensed professional engineers, using state-of-the-art engineering and CAD software. We provide our clients with field placement drawings that minimize interference between materials and maximize the field laborer’s efficiency.
Kustom Krete’s engineers can optimize your existing design for the most efficient use of post-tensioning materials, concrete, and conventional reinforcing steel. Some of the engineering services we offer are:
- Preparation of P/T Design
- Preparation of Field Placement Drawings
- Value Engineering
- Cost Estimating
With Kustom Krete as your partner in construction, you can be assured that the engineering you receive will be of the highest standards. Our clients rely on Kustom Krete to provide them with the cost-saving, engineered solutions that can decrease construction time and reduce building material costs.
Superior performance, minimal maintenance, and reductions in initial and life-cycle costs have created a demand for post-tensioned reinforcements for commercial concrete applications. Commercial applications of post-tensioned concrete such as sports courts, storages yards, production plants, parking areas, and super-flat distribution facilities will all benefit from a post-tensioned reinforcement system from Kustom Krete Post-Tension.
Post-tensioned concrete has a reduced potential for cracking and is capable of handling the stresses of heavy and repetitive loads. The reduction or elimination of control joints in post-tensioned concrete makes it an ideal solution for commercial applications. For super-flat floors and distribution centers requiring high-tolerance floors, post-tensioning is often used to eliminate the closely spaced control joints required in conventionally reinforced slabs-on-ground.
The improved economies and performance of post-tensioned concrete make it a wise choice for long-term commercial applications. Installation times can be reduced with post-tensioned concrete, due to large concrete placements made possible by the elimination of most control joints. In addition, the newly constructed slab can handle most construction loads as soon as the tendons have been stressed, thereby allowing the newly constructed slab construction without causing damage to the slab.
Kustom Krete Post-Tension can provide the materials, stressing equipment, field services, engineering, and detailing necessary to accomplish your post-tensioned commercial slab-on-ground project in a timely and cost-saving manner.
Post-tensioned foundations are actively reinforced, and engineered, to resist soil movement stresses, minimize cracking, and prevent resulting damage to the supported residential structure.
Kustom Krete Post-Tension has provided materials and services to more than a million slab-on-ground foundations. Figures from the Post-Tensioning Institute indicate that more than 50% of all post-tensioning reinforcement used in the United States goes into slab-on-ground foundations, the majority of which are single and multi-family homes.
All types of residential foundations can employ a post-tensioned reinforcement system; including apartments, duplexes, and single family homes. As the traditional borders of our cities expand, builders are faced with significantly more difficult soil conditions. The engineer must desing a foundation solution that will be both economical and effective in withstanding soil induced shrink/ swell movements as well as be able to bridge over subgrade anomalies. A post-tensioned reinforcement system from Kustom Krete Post-Tension allows these criteria to be met, while offering ease of installation and reductions in concrete and reinforcing costs.
For a homeowner, the value is in knowing that their home is built on an engineered foundation that can resist the stresses of soil movements while minimizing unsightly cracking. The homebuilder will appreciate that post-tensioned reinforcement systems costs about the same as traditional reinforcing steel, but with a shorter installation time and reduced field labor costs, resulting in superior performance and a more economical overall solution.
Kustom Krete Post-Tension offers a full range of installation, stressing, and other field services to the slab-onground concrete construction industry.
In selective geographical regions, Kustom Krete offers complete installation and stressing services to compliment the products we furnish. Kustom Krete Post-Tension employs a staff of well-trained and experienced Post-Tensioning Institute Certified Installers and superintendents that have many years of combined field experience in the placement of post-tensioning and conventional reinforcing materials in all types of slab-on-ground applications.
Good service does not end once materials are delivered, and so we strive to offer quality field services tailored to meet the client’s individual project needs and schedules. No matter the project, if it’s post-tensioned we can help.
A post-tensioned reinforcement system in slab-on-ground construction affords the builder and owner significant advantages when compared to conventional reinforcement or wire mesh. Thinner ribs used to stiffen foundations and thinner Uniform Thickness Foundations are the result of using a post-tensioned solution. Savings on concrete material and site preparation time are achievable with a post-tensioned reinforcement system as well. Additionally, control joints are either eliminated or greatly reduced with post-tensioning. Because fewer reinforcing pieces have to be handled, the installation time for a post-tensioned system is often less than that of alternative systems, leading to a savings in labor costs.
Most importantly, a post-tensioned slab is more effective in controlling cracks and resisting bending caused by expansive or hydrocollapsible soils, due to the compression that is applied to the Concrete from the post-tensioning system. As soils expand and contract, conventionally reinforced foundations can deform, which results in excessive bending. This bending can lead to cracking of the foundation and damage to framing elements and architectural finishes, and can cause doors and windows to be out of alignment. A post-tensioned reinforcement system from Kustom Krete Post-Tension is an effective and economic solutions for building on these difficult soil conditions.
Although cracks are likely to develop in any foundation, a well-designed post-tensioned reinforcement system from Kustom Krete Post-Tension will control cracking and prevent any cracks that might form before the tendons are stress from opening, controlling access points for water penetration and insect infestation.
A post-tension reinforced slabon-ground foundation is not only more economical than a conventionally reinforced foundation, but results in a stiffer foundation with less potential for damage to supported structure.
Types of Slab Construction
As in any ground-supported application, the design of a slabon-ground foundation is dependent upon the soil conditions at the project site. A geotechnical engineer will provide a report that will contain information about the soil characteristics that are used to determine which type of foundation can be used.
A typical slab-on-ground foundation falls into three construction types. First is a thin slab, usually 5-inches thick, with a perimeter down turned rib. This type of foundation is used on non-expansive stable soils. The second type is a Ribbed Foundation that has down turned ribs that extend into the soil at 10 to 15-foot centers and a 4 to 5-inch slab. These down turned ribs are generally 10 to 12-inches wide and 20 to 36-inches deep, depending upon the severity of the shrink/swell properties of the soil. A variation of the Ribbed Slab, and the third slab type, is a Uniform Thickness Foundation, which ranges anywhere from 7-1/2 to 20-inches thick, again depending upon the severity of the shrink/swell properties of the soil. The Uniform Thickness Foundation is used most commonly in Arizona, Nevada, and California. There is generally more concrete material used in a Uniform Thickness Foundation; however, the labor savings associated with the elimination of the down turned ribs and the speed of construction offset the additional concrete material cost.