FALL 2013 Newsletter

Stabilizing Cellular Towers, Compaction Grouting & Expansive Soils

STABILIZING CELLULAR TOWERS

Cellular towers are everywhere, they come in various types and in some areas companies are required to camouflage them due to local opposition.  You may see them camouflaged as a palm tree or a steel structure decorated with colored glass.  But most often, they stick out like a sore thumb, huddled together with satellites on a tall buildings roof, or in rural areas, as extremely tall tower held with high tension wires to hold it in place.

Colorado Grouting had the unique opportunity to do repairs to two of these tall towers in rural southeast Colorado, and we would like to share with you that adventure for our summer 2013 newsletter.

A Unique Situation:

The two towers were originally built with a poor compaction underneath the foundation for the cell towers and the loose fill was a primary cause of the tower settlement problem.  This caused differential movement of 1” to 1 ½” since construction in 2007. One recommendation for a suitable repair was Compaction Grouting. 

Doing the repairs:

After marking out the outline of the foundation pad underneath the tower base, we took elevation shots to see where the tower was standing before grouting. As the weight and height of the tower is so immense, we had to be extra cautious to not disturb the intricate rebar layout inside the foundation when choosing where our compaction holes were going to be drilled.  To core drill locations a specialized rock drill was used in case we came across rebar, as you can see in the photos.  We then water drilled 5 locations around the pad up to 7 ½’ below the pad.  We pumped a grouting material into the unstable soils and lifted the pad to become more stable. We then had two custom concrete pieces made to further stabilize the towers pier at the base and mixed concrete and molded it together with grout

We were able to lift the pad to a level platform, using up to as much as 6.34 Yards of grouting material and in some cases lifting the pad up as much as 3 9/16”.  Thus greatly restoring the stability of such a tall structure.

Filling the void: Compaction Grouting

Compaction Grouting is a technique used to fill in voids under the ground.  For Compaction Grouting, a high viscosity grout material is commonly used for injection into the soils.  As the grout mass expands, the surrounding soil is displaced and densified. Compaction Grouting began in the United States in the 1950’s and is a successful technique used to correct structural settlement, helping to densify soils.  Typically an injection pipe is advanced to the maximum treatment depth.  The grout material is then injected as the pipe is slowly extracted in lifts, creating a column of overlapping grout bulbs.  Compaction Grouting can be accomplished where access may be difficult or space is limited.  If you think you have problems with your home’s foundation and are interested in finding out if Compaction Grouting can be used to fix any settlement problems, call us at Colorado Grouting and we will be glad to answer any questions you may have.

Expansive Soils, A Definition

Expansive soils are soils that contain water – absorbing minerals.  These soils expand as the take in water, and can cause damage to buildings and other structures due to the force they exert as they expand.

Expansive soil is a very common cause of foundation problems.  During times of high moisture, soils which are expansive will heave and can cause lifting of a building or other structure, whereas little or no moisture in the soil can collapse, causing the structure to settle.

Expansive soils can exert pressure on the vertical face of a foundation, basement or retaining wall resulting in lateral movement.

If you are experiencing problems with your homes foundation, give us a call and we can come out and take a look and get you on the right track for any repairs you may need.

To Visit Our Website: CLICK HERE

Our Phone: (719) 543-7670
Our Fax:     (719)546-0963

 

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Author: M. Harper, Colorado Grouting.