cold weather requirements for masonry construction
TRANSCRIPT
BAC CONTRACTORS
IMI-TRAINED CRAFTWORKERS
International Union of Bricklayers and Allied Craftworkers
International Masonry Institute
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conclusion of this presentation.
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© International Masonry Institute 2015
COPYRIGHTED MATERIALS
1. understand - code requirements for cold weather masonry construction
IBC 2012/MSJC 2011 IBC 2015/MSJC 2013
2. learn - Industry Guidelines and Common Practice 3. apply - appropriate actions for successful results 4. learn – helpful tips to plan for winter construction
LEARNING OBJECTIVES
SPECIFICATION FOR MASONRY STRUCTURES
PART 1 - GENERAL
1.5 - Submittals
1.5 B. Submit the following:
3. Construction procedures
a. Cold weather construction procedures
IBC & MSJC
BUILDING CODES
2015 IBC goes with 2013 MSJC
MSJC date will be one or two years prior to companion IBC
IBC supersedes MSJC at points of conflict
IBC: the legally adopted model code
MSJC: the referenced standard
2015 INTERNATIONAL BUILDING CODE
SECTION 2101 GENERAL
2101.2.6 Masonry Veneer
CHAPTER 21 - MASONRY
Masonry veneer shall comply
with the provisions of Chapter 14
or Chapter 6 of TMS 402/ACI
530/ASCE 5.
SECTION 2104 CONSTRUCTION
2104.1 Masonry Construction
Masonry construction shall
comply with the requirements of
Sections 2104.1.1 through
2104.4 and with TMS 402/ACI
530/ASCE 5.
CODE COMPARISONS
IBC ‘03 & ‘06 MSJC ‘02, ‘05, ’08,
’11, ‘13
PART 1 - GENERAL 1.8 – Project Conditions
1.8 C. Cold weather construction
Chapter 21: MASONRY Section 2104.3
Cold weather construction
but not ’09, ’12, ‘15
Beginning in 2009, IBC does NOT
have hot/cold weather provisions.
All are moved to the 2008 MSJC
CODE COMPARISONS
IBC 2104.3 (’06)
Cold Weather Construction ◦ The cold weather
construction provisions of ACI 530.1, (etc.) Article 1.8C OR the following procedures shall. . .when EITHER the ambient temp, OR the temp of masonry units is below 40o F.(4o C)
◦ Visible ice and snow shall be removed…
MSJC 1.8C (’08, ’11, ‘13)
Cold Weather Construction ◦ 1. Implement the following
requirements when: The ambient temperature falls
below 40oF (4.4oC) Do not lay units having either
a temp of 20oF (-6.7oC) or visible frozen
moisture
WHEN MUST COLD WEATHER PROVISION BE IMPLEMENTED?
WHY 40º ?
The temperature at which hydration of cement slows and eventually stops
Supported by research and decades of empirical evidence
Hydration is the ability of the cement to take on water and complete its chemical reaction. No hydration = no strength development
The chemical process of hydration produces heat
PERFORMANCE TARGETS
Keep the mortar between 40oF and 120oF
Don’t lay frozen units or allow the masonry to freeze before initial set
Protect the masonry from freezing after construction
Result: the masonry will perform as expected
SPECIFICALLY…
1. General Provisions
Apply to all types, all temperatures
2. Construction Provisions
Options available for how to meet targets based on job site conditions
3. Protection Provisions
Care for the masonry during and after construction
TEMPERATURE
Ambient Temperature: Current outdoor temperature at the time considered
Mean Daily Temperature: Average of the projected maximum and minimum daily temperature, midnight to midnight
Anticipated Daily Minimums: Lowest temperature forecast for the upcoming 24 hrs.
TEMPERATURE
Ambient temperature
Construction
Mean Daily Temperature
Protection, ungrouted masonry
Anticipated Daily Minimum
Protection, grouted masonry
TEMPERATURE
Mean Daily Temperature
Average of the projected
maximum and minimum daily
temperature, midnight to midnight
54º + 36º / 2 = 45º
Ambient Temperature
Current outdoor
temperature at the time
considered.
Anticipated Daily
Minimum
Lowest temp
forecast for the
upcoming 24 hrs.
considered for construction
considered for protection, ungrouted masonry
considered for protection, grouted masonry
TEMPERATURE Anticipated Daily Minimum
Lowest temp forecast for the
upcoming 24 hours
considered for protection, grouted masonry
GENERAL PROVISIONS
Keep units and other materials dry
Do not lay frozen units (units < 20o) or those with visible ice or snow
Do not overheat water or aggregates
It is not necessary to heat grout materials unless their temps are below 32o
protected not protected
Keep units and other materials dry
Do not lay frozen units or those with visible ice or snow
40o – 32o F
CONSTRUCTION PROVISIONS
Do not lay glass units below 40o
Heat sand OR water to achieve mortar temps of 40o – 120o at time of mixing
32o to 25o F
CONSTRUCTION PROVISIONS
All of the above, plus:
Heat sand AND water to achieve mortar temps of 40o – 120o at time of mixing
Maintain materials above 32oF until used
Heat grout aggregate and water to keep grout above 70oF
25o to 20o F
CONSTRUCTION PROVISIONS
All of the above, plus:
Add windbreaks or enclosures when wind is above 15 mph
Make sure masonry is above 40o before grouting
CONSTRUCTION PROVISIONS
20o F and below
All of the above, plus:
Add auxiliary heat to enclosures
Keep enclosed area above 32o F
CONSTRUCTION PROVISIONS
Heating water is the most effective technique because of its ability to retain heat and impart heat to other ingredients
IBC2104.7 Masonry
Protection
◦ The top of unfinished
masonry work shall
be covered to protect
the masonry from the
weather.
MSJC 1.8B Masonry
Protection
◦ Cover top of
unfinished masonry
work to protect it from
the weather.
Note: These provisions apply
regardless of temperature.
PROTECTION REQUIREMENTS
IBC 2006: 2104.3.3- 2104.3.3.3.5 ◦ 6. Where mean daily
temperatures are between [all ranges down past 20oF(-7oC)], completed masonry shall be completely covered with a weather-resistant membrane for 24 hours after construction.
MSJC 2011 1.8C ◦ 7. When mean daily
temperature is between [all ranges down past 20oF (-6.7o C)], completely cover completed masonry with a weather-resistive membrane for 24 hr after construction.
Note: These are reference locations for those using
the 2006 IBC/2005 MSJC and prior. These are found
only in the MSJC from the 2005 edition forward.
PROTECTION, UNGROUTED MASONRY
Temperature Ranges for Protection Based on
“Mean daily” temperatures for ungrouted
masonry (forecast 24-hour average)
“Anticipated daily minimum” temperatures for
grouted masonry (forecast anticipated minimum)
PROTECTION REQUIREMENTS
40o – 32o F
◦Maintain glass unit masonry above 40o
for 48 hours
◦ Protect newly-laid masonry with weather-
resistant membrane for 24 hours
PROTECTION REQUIREMENTS
32o – 25o F
◦Repeats requirement
from prior temp range
– cover for 24 hours
PROTECTION REQUIREMENTS
◦ (no additional
requirements)
25o – 20o F
The above, plus
◦ For ungrouted masonry, cover
completely with insulating blankets, or
equal, for 24 hours
◦ Increase to 48 hours for grouted
masonry unless Type III cement only is
used in grout. (New in 2003 IBC)
PROTECTION REQUIREMENTS
20o F and below
◦ The above, plus:
◦Maintain new masonry above 32o for 24
hours with heated enclosures, lamps, etc.
◦ Increase to 48 hours for grouted masonry
unless Type III cement only is used in
grout.
PROTECTION REQUIREMENTS
Heated enclosure
PROTECTION OF MATERIALS
Enclosure on site made from scaffold framing and heavy plastic sheeting
300,000 BTU heater
Thermostat set to 50oF over the weekend
6 pallets of block and drum of water
In cold weather, bricks
with IRA of 25-30 may be
desirable
5-25 g/min/30 in 2 Recommendation:
INITIAL RATE OF ABSORPTION
Using a high IRA brick
reduces the risk of
freezing by more rapidly
absorbing water from
the mortar or grout.
INITIAL RATE OF ABSORPTION
If a low IRA brick is
used, water content of
the mortar should be
the minimum necessary
for workability
© 2009 INTERNATIONAL MASONRY INSTITUTE
ELEVATIONS DIAGRAM 01.410.0311 REV. 08/10/09
MORTAR JOINT MATERIAL TAKEOFF
UTILITY BRICK, RUNNING BOND MODULAR BRICK, RUNNING BOND
4 @ 12” x 3/8” = 18.000 SQ. IN. BED JOINTS
HEAD JOINTS 8 @ 2.3125” x 3/8” = 6.938 SQ. IN.
2 @ 1.3125” x 3/8” = 0.984 SQ. IN.
25.922 SQ. IN. MORTAR
3 @ 12” x 3/8” = 13.500 SQ. IN.
3 @ 3.625” x 3/8” = 4.078 SQ. IN.
17.578 SQ. IN. MORTAR
18.00% MORTAR 12.21% MORTAR
ONE SQUARE FOOT ONE SQUARE FOOT
18% 12%
MORTAR
Cold weather retards the hydration of the cement in the mortar mix.
Mortar mixed in cold weather often has lower water content, increased air content, and reduced early strength.
Mortar with lower lime content will allow the water content to decrease more rapidly
Mortar with over 6% water content will experience disruptive expansive forces if frozen, due to the increase in volume of water when it converts to ice.
Avoid scorching the sand or overheating the water, which can lead to discolored mortar and flash setting.
Avoid wide variations in mortar temps, causing variations in tooling times and possible variations in mortar color.
MORTAR
Highly
magnified,
frozen mortar
has fissures
that can
reduce
compressive
strength and
inhibit bond
MORTAR
ADMIXTURES
Accelerators are admixtures used to speed the setting time of mortar and grout.
By increasing the rate of hydration, accelerators increase the rate of early strength gain.
Avoid calcium chloride: it causes corrosion to metal accessories and possibly efflorescence.
Safer: accelerators w/ inorganic nonchloride compounds like calcium nitrite and calcium nitrate.
Avoid antifreeze: it reduces compressive and bond strength of mortar.
ARCHITECTURAL EFFECT DETAIL 01.601 REV. 08/31/07
BRIC
K &
BLO
CK C
AV
ITY W
ALL
MORTAR
WASH
DETAILING MASONRY
SERIES www.imiweb.org 800-IMI-0988
International Masonry Institute
PRODUCTION
If contractor figured job with pipe scaffold, (e.g. loadbearing) add 5-7% more for cold weather construction
If contractor figured job w/ hydromobile scaffold, add 15-20% for cold weather construction
If normal conditions call for 4 laborers for every 8 bricklayers, cold weather conditions call for 5 laborers
Production slows down, e.g. cut rebar into shorter pieces to work around enclosure
Code provisions
+ Planning
+ Skilled Execution
= Successful cold weather masonry construction
FOR GOOD RESULTS
For best masonry performance in cold weather
conditions:
◦ Mason contractors: Plan ahead and submit a
plan, if required
◦ Be flexible, the weather is unpredictable
◦ Remember that top performance is the goal
and the code allows for the application of
reason and common sense.
FOR GOOD RESULTS
General Preparation and Construction Requirements: Store units and other materials in dry conditions off the ground. Do not lay frozen
units (those with temperatures below 20o F) or those with visible ice or snow. Do not heat water or aggregates above 140o F. It’s not
necessary to heat grout materials unless their temperatures are below 32o F.
TEMPERATURE
RANGES
CONSTRUCTION REQUIREMENTS
Ambient Temperatures
(During Construction)
PROTECTION REQUIREMENTS
Mean daily temps for un-grouted masonry, and
anticipated daily minimums for grouted masonry for
period following construction
40o F to 32o F Do not lay glass units.
Heat sand or water to achieve mortar
temps of 40o F to 120o F, at time of mixing.
Maintain glass unit masonry above 40o F for
48-hours.
Protect newly laid masonry with weather-resistant
membrane for 24-hours.
32o F to 25o F
Maintain materials above 32o F until used.
Heat grout aggregate & water.
Keep grout above 70o F.
No additional requirements beyond those above.
25o F to 20o F
Add windbreaks or enclosures when wind
exceeds 15 mph.
Heat masonry to 40o F prior to grouting.
Cover new masonry completely with insulating
blankets, or equal, for 24-hours.
Increase to 48-hours for grouted masonry unless
Type III cement only is used.
20o F and Below
Add auxiliary heat to enclosures.
Keep area above 32o F.
Maintain new masonry temps above 32o F for 24-
hours with heated enclosures, lamps, etc.
MSJC-13 COLD WEATHER REQUIREMENTS
IMI Tech Briefs,
Document 2.5.6
(Included in your
handouts)
BIA Technical Note #1
(www.bia.org)
NCMA Tek Note 3-1C
www.ncma.org)
NCMA Tek Note 1-2B
Portland Cement
Association (PCA)
(www.cement.org)
ADDITIONAL RESOURCES
BAC CONTRACTORS
IMI-TRAINED CRAFTWORKERS
International Union of Bricklayers and Allied Craftworkers
International Masonry Institute