Dexpan - FAQ's

Which type of Dexpan should I use?

Dexpan is temperature sensitive. Select the correct version of Dexpan (Type 1, 2 or 3) based primarily on the core temperature of the material to be broken (not the air temperature). 

           Dexpan Type 1    25 to 40°C   (77 to 104°F)
           Dexpan Type 2    10 to 25°C   (50 to 77°F)
           Dexpan Type 3   -5 to 10°C   (23 to 50°F)

The ambient temperature (expected low, high) and weather forecast for outside projects are also considerations. 


What happens if I use the wrong type of Dexpan?

Like all expansive grouts, Dexpan is temperature sensitive.

If you use a version of Dexpan formulated for cooler material, you run the risk and danger of blowouts.  (What causes blowouts LINK). 

If you use a version of Dexpan formulated for warmer materials and conditions, the Dexpan may not work or could take up to 3 - 5 days to crack your material and achieve optimal expansion.

Examples:
1. If your rock or concrete has a core temperature approaching or above 25 °C, Dexpan Type 1 must be used. 
DANGER:  If you try using Dexpan 2 at 25 °C and above, the reaction may occur too quickly and blowouts may occur.

2. If your rock or concrete has a core temperature approaching or above 10°C (up to 25 °C), Dexpan Type 2 must be used. DANGER:  If you try using Dexpan 3 approaching 10°C and warmer, the reaction may occur too quickly and blowouts may occur.

3. If your rock or concrete has a core temperature below 10°C, Dexpan Type 3 should be used.  IMPORTANT: If you try using Type 2, Dexpan may not work at all or take 3 - 5 days to crack and/or achieve smaller cracks, less extensive cracking.

How much Dexpan do I need?

  1. Consider total # of holes you will need to drill

  2. Consider depth you will need to drill based on project objectives

  3. Calculate total linear feet of Dexpan you will consume:
    # of holes to fill with Dexpan x depth of holes in feet = linear feet

  4. Divide total linear feet by 36 = # of boxes required.

What is the yield of a bag / box of Dexpan?

Dexpan Quantity Yield
1 Pail One 11 lb bag 9 linear feet
1 Box 44 lb (4 x 11 lb bags per box) 36 linear feet
1 pallet 50 x 44 lb boxes 1,800 linear feet
1/2 half container 450 x 44 lb boxes 16,200 linear feet

What are the safety considerations when using Dexpan?

Due to the highly alkaline nature of the product:
›  risk of serious eye damage
›  may cause skin irritation if left on skin
›  inhalation of dust may irritate respiratory system or lungs

ALWAYS:
›  use personal protective equipment:
         safety goggles             rubber gloves
         dust-proof mask           proper clothing
›  Select correct Dexpan product type given material temperature
›  Ensure adequate ventilation in confined spaces
›  Mix promptly ensuring mixture is poured into holes within 5 - 10 minutes of combining powder & water
›  Start with an empty bucket (do not add 2nd bag to any left-over mixture)
›  Cover filled holes with a tarp

NEVER:
›  look or stand over filled holes
›  pour mixture into hot holes
›  use warm water for mixing
›  leave excess product sitting in bucket
›  use glass or enclosed cans to mix/pour Dexpan (could lead to a blow-out with glass or metal fragments)

 

How long does it take to work?

Factors affecting the timing for cracks to appear include:
›  material temperature
›  material hardness
›  reinforcing present
›  available expansion space
›  number and spacing of drilled holes
›  depth and diameter of drilled holes
›  temperature fluctuations (material, ambient)

Warm & Hot Conditions
Small cracks can begin to appear as early as 12 hours, but waiting for 24, 36 or 48 hours will result in more extensive and wider cracks.  

Cool & Cold Conditions
Expansion and cracking is slower. Depending upon conditions and factors listed above, it may take 36 hours and up to 4 days for optimal expansion and cracking.

What are the common mistakes people make? 

1.  Not reading the instructions fully.
2.  Using the wrong product for the conditions.  Choose the version of Dexpan based on the core temperature of the material (concrete, rock) you want to break, not the air temperature.
3. Not taking into account Dexpan requires and open face or expansion room to crack, expand and break apart.
4. Not drilling proper diameter holes. We highly recommend 1-1/2” holes to ensure sufficient volume of mixture in the hole to generate required expansive pressure.
5. Taking too long between mixing the Dexpan with water and pouring into the drilled holes. Fill holes within 5 to 10 minutes.
6. Filling holes without consideration of open face or expansion room. Fill row of holes closest to the open face first, then the row behind.
7. Using on materials that are less than 7” thick.
8. Drilling completely through a material so that the bottom of the hole is not fully enclosed.
9. Drilling holes at irregular depths. Dexpan is most effective when adjoining drilled holes are equal depth allowing them to work “together.”
10. Impatience.  Give Dexpan a full 24 to 48 hours to achieve fuller expansion, wider cracking.

 

Will Dexpan work for ALL shallow applications?

No.  For Dexpan to be effective, we strongly recommend materials to be cracked be a MINIMUM of 7" in depth.  
Contact Us for more information if you have a project 4 - 6” that you desperately need pre-cracked.

What equipment is required?

Drill & carbide bit to create holes
Mixing bucket
Electric hand drill with mixing paddle
1.5 L of clean cool water per bag of Dexpan
Safety goggles           
Rubber gloves
Dust-proof mask
Proper clothing
Funnel (optional)

 

 

Why is it important to ensure sufficient empty space around the rock or concrete to be cracked?

For Dexpan to be effective, the material needs an open face or room to expand and break apart.  Breaking rock or concrete enclosed on all sides does not allow room for expansive pressure created by Dexpan to crack and break the material. 

 

Why is planning your drill pattern so important?

A well-designed hole-drilling pattern will:
›  improve effectiveness of Dexpan  
›  save money in quantity of Dexpan consumed
›  reduces labour by reducing time spent drilling/filling holes
›  reduces labour cost by pre-cracking difficult materials making demolition and removal easier
›  allows for more targeted and controlled breaking  
›  gets the job done right, the first time
›  protects any sensitive surrounding structures

 

Our project doesn’t have an open face and is enclosed on all sides, what can we do?

There are a number of alternatives to create the necessary expansion space:
›  dig around or remove soil tightly enclosing rock or boulders to be cracked  
›  drill a series of empty relief or perimeter holes  
›  in a concrete slab, employ holes drilled at 45° angle (to direct expansion upwards) in the centre of the slab

 

How should I drill the holes?

Spacing, depth and drill pattern should be adjusted based on:
›  project objectives (demo, dimension, pre-crack)
›  material density
›  presence of reinforcing
›  desired size of broken material
›  desired cracking time
> if you need to protect an adjoining structure

                         Reinforced     Hard      Soft      
                          Concrete      Rock      Rock     Concrete    Boulders

Diameter               1.5”            1.5”        1.5”           1.5”              1.5”
Spacing             10 - 12”      10 - 12”      10”       10 - 12”            10”
Depth                  90%          105%      105%        80%             75%

Depending upon the material, project objectives and hole diameter, it is sometimes possible to space holes 12 to 16" apart.

What is the purpose of drilling relief holes and leaving them empty?

Holes drilled, but not filled with Dexpan mixture can:
›  create expansion room for material to break apart when the case is enclosed or confined
›  direct and control cracking  
›  reduce amount of Dexpan required
›  shorten time for breaking to occur
›  control breaking to protect part of a structure
›  direct fracturing
> create corners when creating openings or quarrying stone

 

What is the impact of drilling more holes, closer together?

More holes spaced closer together results in: 
›  faster break times
›  smaller more manageable pieces
›  adds labour cost (drilling & filling more holes)
›  may increase quantity of Dexpan used

 

How big or small can I drill my holes?

For best results, we highly recommend 1.5" diameter holes.  
Do not exceed 2” or go less than 1” in diameter.
Using smaller diameter holes will require holes to be spaced closer together and may NOT be successful in some materials.

 

How will drilling a different diameter hole affect spacing?

Depending on the density of the material and/or reinforcing present:
    2” Diameter Holes
    You may be able to space holes 12” to  18” apart
    1" Diameter Holes (smaller than we recommend)
    You may need to drill the holes 4 - 8" apart. 1” diameter holes may be ineffective in some materials.

 

When is the best time to pour Dexpan?

The best time to pour Dexpan is when the material temperature is coldest and material can gradually warm as the day progresses.  

An effective strategy is to drill holes the day before so you can pour first thing early the next morning. 

Pouring the Dexpan in the morning, when material is coolest, is HIGHLY recommended in extremely hot temperatures.  

What can cause expansive demolition grouts to blowout?

1. Using wrong version of Dexpan based on the rock or concrete core temperature.
2. Pouring grout mixture into warm or hot holes.
3. Hole diameter is too large.
4. Hole depth is too shallow. Drill holes to a minimum depth of 5 times the hole diameter.
5. Distance between holes is too large.
6. No open face or expansion room for material to expand, crack and break apart.
7. Mixing more than 1 bag of expansive grout at a time resulting in #9 below.
8. Mixing expansive grout by hand vs. using electric hand drill with mixing paddle attachment resulting in #9 below.
9. Too much time passing between beginning to mix and pouring into holes. Pour Dexpan mixture into holes within 5-10 minutes.
10. Adding expansive grout and water to a bucket with leftover mixture remaining from previously mixed batch.
11. Too much dust in holes.
12. Not measuring water. Using too little water.
13. Using warm water. In warm conditions it is crucial to use cold or ice water.
14. Dexpan boxes sitting in sunlight or warm conditions before being mixed with water.
15. Filled holes exposed to hot direct sunshine.
16. Filling holes incorrectly. Always fill row of holes closest to your open face first, pouring left to right; next row, back to the start, pour left to right.

IMPORTANT
All brands of expansive demolition grouts are susceptible to blowouts if the wrong product is used or instructions are not followed.
Use the correct version of expansive grout based on your material core temperature.
Never stand directly above or look into filled holes.
Early or warning signs do not always precede blowouts. If filled holes start to smoke or steam, that could be a sign they may be about to blow out. Clear the area of people immediately.

Any tips for using Dexpan in freezing cold conditions?

1. Ensure correct type of Dexpan is used (Type 3) and stored at 10 degrees Celsius until ready to use.
2. Drill 1.5" diameter holes at 1 foot spacing (filled with Dexpan). To speed up and assist cracking, drill 1/2 to 3/4" diameter relief/expansion holes in between the filled holes (leave them empty).
3. Ensure water temperature is luke warm (approx 10 degrees Celsius), Caution: Cooler water will delay the cracking and DO NOT overheat the water as this could lead to BLOW OUTS.
4. Fill holes in morning so any natural temperature rise during the day supports the reaction vs pouring in afternoon when the temperature might drop overnight and work against the reaction.
5. After you fill the holes, cover with a tarp to help seal in the heat.
6. In extreme cold weather, time sensitive projects some customers have erected hoarding and used heaters to keep the temperature within the recommended range.
7. PATIENCE. It might take 36 or up to 72+ hours for full cracking in extreme cold conditions. If the Dexpan is still clay-like and firm to the touch, it is still working.

Dexpan Video Instructions

Dexpan Admin