October 3, 2014
Hard to believe that we are entering the 4th quarter of 2014. Where has the time gone? It has been a very busy year at ICS thus far and we are moving full steam ahead. None of us want to talk about or admit it, but cold weather will soon be upon us. This is an excellent time to review setting Indiana Limestone in cold weather. The tips below will provide for a successful setting job.
Cold Weather Setting
The bond strength of mortar is considerably reduced when mortar is frozen prior to hardening. The chemical reaction between water and cement (hydration) progresses very slowly below 40 degrees F. Protection is necessary if the outside air temperature is 40 degrees and falling.
Admixtures or anti-freezes should not be used to lower the freezing point of mortar. The effectiveness of most of these compounds is due to the calcium chloride they contain acting as accelerators.
Calcium chloride cannot be used on limestone. Salts cause efflorescence and may cause spalling or flaking through recrystallization (crystal growth).
Heating all materials must be considered. Sand contains some moisture that will form ice when stored in freezing temperatures and must be heated to thaw the ice. Sand must be heated slowly to prevent scorching. Mixing water should not be above 160 degrees F to prevent the danger of flash set with cement. The mortars should be between 40 and 120 degrees F when used.
Stone should be covered with tarpaulin, felt paper, or polyethylene, and heating units used to warm the stone. Caution must be used to prevent smoke under the covering from salamanders.
Never set stone on a snow or ice-covered bed. Bond cannot develop between the mortar bed and frozen supporting surfaces. If stone is to be set during cold weather the cold weather masonry construction recommendations of the International Masonry Industry All-weather Council should be followed.
Cold Weather Masonry Construction and Protective Recommendations
by the INTERNATIONAL MASONRY INDUSTRY ALL-WEATHER COUNCIL
The consensus of this Council regarding recommendations for cold weather masonry construction and protection is as follows:
Work Day Temperature: Above 40 F
Construction Equipment: Normal masonry procedure
Protection Equipment: Cover walls with plastic or canvas at end of work day to prevent water from entering masonry.
Work Day Temperature: 40 F – 32 F
Construction Equipment: Heat mixing water to produce mortar temps between 40F-120F
Protection Equipment: Cover walls & materials to prevent wetting and freezing. Covers should be plastic or canvas.
Work Day Temperature: 32 F – 25 F
Construction Equipment: Heat mixing waters and sand to produce mortar temps between 40F-120F.
Protection Equipment: With wind velocities over 15mph provide windbreaks during the work and cover walls & materials at the end of the day to prevent wetting and freezing.
Work Day Temperature: 25 F – 20 F
Construction Equipment: Mortar on boards should be maintained above 40F.
Protection Equipment: Maintain masonry above freezing for 16 hours using auxiliary heat or insulated blankets.
Work Day Temperature: 20 F – 0 F and below
Construction Equipment: Heat mixing water and sand to produce mortar sufficient temps between 40F-120F.
Protection Equipment: Provide enclosures and supply heat to maintain masonry enclosure above 32F for 24 hours.
New Shop Drawing Return Procedure
Effective immediately, ICS has a new shop drawing return procedure. We have encountered problems with returned approved shop drawings being sent via email and now require a follow up phone call to confirm the drawings have been received by someone in our office. This new procedure will be beneficial to all parties by reducing the risk of delays in fabrication.
Feature project for this quarter is the Indianapolis Fire Station 5 project. This project features a brick & stone exterior complement by a large carved Station plaque, arched door heads, banding and split face wainscoting. Indianapolis Fire Department Station #5 achieved LEED® Silver Certification and was built to resemble the original Station #5 built in 1874.