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Structural

Crack Monitors

Gauge_5_2-12472-297x300 Crack MonitorsCracks in brick walls are common.  Figuring out whether or not they are serious and why they are happening can be challenging.  Crack monitors can be installed to help document which way the wall is moving and how fast.  We recommend that the monitors be left in place for at least a year, or until the movement becomes alarming.  It is important to know if the wall movement is attributable to natural seasonal temperature changes or possible foundation settlement.  Knowing why the wall is moving lets us determine what the proper repair should be.  Sometimes a simple caulk joint can be the right fix, or a more expensive foundation underpinning project make be required.

Whatcha Think?

Aggregates are added to concrete for what reason?question-300x217 Whatcha Think?

1) Inexpensive filler  2) Improved workablility  3) Dimensional stability  4) Increased wear resistance  5) All of the Above

All of the above is the correct choice.  Basic concrete consists of the paste (Portland cement & water),  fine aggregate (sand) and coarse aggregate (crused stone or gravel).  Aggregates can account for up to 75% of the volume of concrete and are considerably less expensive than the Portland cement.  They also play a substantial role in determining workability, strength, dimensional stability, and durablity of the concrete.

Hammering Out Concrete Problems

hammer-132x300 Hammering Out Concrete ProblemsIf you have a concern about the integrity of cracked or spalled concrete, consider using a simple but reliable test.

Tap the concrete with a hammer.  A sharp, ringing sound tends to indicate that the concrete is sound.  A dull hollow sound means that the concrete may be unsound, unbonded, delaminated or deteriorated.

It sounds simple and it is…….hammer away!

Just Breathe

Installing linoleum or similar covering directly on concrete floors can be problematic if there is moisture in the slab.  This is especially a concern with on grade slabs where there may be moisture under the slab that can permeate upward.   Linoleum and similar floorflooring-300x200 Just Breathe coverings act as a barrier that can cause moisture to be trapped under the flooring.  When this happens, the floor covering can unbond, warp and become a serious hazard.

Carpet covering will let moisture vapor pass through and normally are not a problem.  Carpet can be a solution where other floor coverings are adversely affected by moisture.

If a linoleum or similar covering needs to be installed, it is important to understand and analyze the moisture present in and/or under the slab.  Various types of moisture testing can be performed to help verify that the concrete is dry enough to allow the installation of an impermeable floor covering.

Using Sacrificial Zinc Anodes to Inhibit Corrosion

zinc1-300x225 Using Sacrificial Zinc Anodes to Inhibit CorrosionWhen repairing concrete damage caused by embedded steel corrosion, it may not be enough to simply remove and replace. In applications where the existing steel, after being cleaned and coated, will come into contact with both old concrete and new patch material, accelerated corrosion is possible due to the differences in electrical potential between the old and new materials. To prevent corrosion, zinc anodes can be installed prior to new concrete placement. The zinc, which has a higher corrosion potential than steel, will corrode in preference to the more noble metal, steel.

Preventing a Building Collapse

collaspe5-174x300 Preventing a Building Collapse Several concrete columns in the basement of a local 11-story apartment building were noted by Management as being severely cracked.  A Contractor was hired to make the repairs to these columns that supported all floors of the living spaces above.  Heavy duty shoring was installed so that the “Jenga-like” repair process could be safely performed and the building could remain in service.  After the deteriorated concrete was removed, we found severely corroded steel reinforcement that indicated that the structural integrity of the columns were severely compromised.  The repairs were performed in the nick of time.

Use Caution With SIP Construction!

Structural insulated panels (SIP) are a prefabricated assembly of rigid foam insulation sandwiched between layers of structural boards, often oriented-strand board (OSB). These panels are used for walls, floors and roofs for caution-300x227 Use Caution With SIP Construction!homes in place of “conventional” stick-built construction.

While SIPs have been  around for a long time, they are currently gaining a lot of attention and many home builders are making SIP panels a part of there regular construction or at least offer it as an option.

As with most anything, SIP construction has several pros and cons. On the pro side, they are very energy efficient, mechanically sound and quick to construct. On the other side, they are normally more expensive than conventional framing and the consequences of poor fabrication and/or defective installation can be extremely difficult to correct.

Caution needs to be used when deciding on SIP construction. The fabricators and installers must be properly trained to avoid severe problems. People involved with conventional, stick-built home construction are not qualified to perform SIP construction unless they receive the proper training. In addition, the cutting of holes in SIP panels (for skylights or other items) must be carefully reviewed to avoid compromising panel integrity.

A Modern Touch

before1-150x150 A Modern Touch

 

We have retrofitted the upper level of a concrete parking garage with post tension cable rails in lieu of masonry flower block walls.  You can see that the parking level looks more clean and neat with the new rails.  Also rain water drains off the parking deck much faster with the open before1-150x150 A Modern Touchcable design.  The new rails are more safe as they are designed to resist vehicle impact per the Building Code, which was important to the Owner because on two separate occasions cars have crashed through the old block walls (when the gas was pressed and not the brake) and fell two stories to the ground below.

Caulk? Maybe Not!

Applying caulk to stop leaks is not always a good thing.  caulk-300x300 Caulk? Maybe Not!Sometimes it makes matters worse by trapping water in the building façade instead of letting it drain.  Here are a few areas where NOT to caulk:

*Along window or door head lintels on brick facades – leads to advanced corrosion of the steel support and either rotated/deflected steel or cracked bricks.

*Soffit (ceiling) of elevated concrete slabs (i.e. balconies, parking garage slabs) – traps water in the concrete and accelerates corrosion of the embedded steel and deterioration of the concrete

*Over/covering window weep holes – prevents windows from draining properly

Screw It!

Parts of Alexandria, Virginia are known to have shrink/swell (marine) clay IMG_2307-RESAMPLE1-300x225 Screw It!soils.  Placing a building on these unstable soils can result in differential building settlement as the moisture content of the soils varies during seasons of drought and rain.  Over time settlement conditions can result in unsafe conditions and impending structural failures.  We just completed a large foundation underpinning project, which restored the structural stability of several buildings by using helical piers.  Helical piers are large “screws” that are threaded into the ground, in our case up to 80-feet deep, to a layer of good soil and are used to support the building foundation.  (The attached photo shows cracked foundation)