Burden - Distance between holes perpendicular to front face. (If burden is 18 inches then first
row of holes from face is 9 inches away.)
Spacing - Distance between holes parallel to face
Patterns that are effective
When in doubt start by trying hole pattern that is 10 times hole diameter (1.5" hole = 15 inches between holes)
Diamond pattern - this usually works better than a square "pattern" (cracks usually go from a hole to open face
at a 45 deg angle rather than straight to edge)
Rectangular pattern is often more effective than square depending on number of holes in row. Reduce burden and
increase spacing. This is because it is easier to crack parallel to a face then out to it and you need more force to
break out to face so holes in burden work best closer together. You can usually only do 3-4 holes in burden row per break.
This same principle applies in breaking with explosives.
Concrete
If removal is by hand, consider grid that makes drilling through rebar easiest. Since most rebar is placed on 6" increments,
hole pattern should reflect this. Best is usually 1 foot centers. Drill starter hole in concrete 6 to 8" in from edge, once
you establish rebar location, lay out holes in increments to miss rebar. Much more effective than laying out a pattern, having
driller hit steel and then compensating for rebar.
Trenching or cutting a piece out of a face
The drill pattern should have a "pre-split" pattern of holes on spacing 1/2 of what is used in the mass of the same area.
Every other hole is filled with Dā-mite® in the pre-split. This will help isolate the rock. Normally,
the product will not break beyond the last row of holes; therefore, defining the area of the pit to be excavated. If there is
not a free face in the pit or in the trench, then a free face needs to be created. Depending on the job conditions, this can be
accomplished by drilling a slot or by drilling angled holes. Daigh Company can assist you on how to create these free faces.
The typical amount of product needed per cubic yard can vary and is determined by knowing the width of trench, the hole spacing
and the % of hole depth that is to be sub drilled. Most yields of Dā-mite® per cubic yard in trenching
will be in the range of 12kg/cyd to 25 kg/ cyd"
Temperature of Material to be broken
Know the temperature of what you are breaking and choose correct grade of Dā-mite® In hot temperatures
use ice water to make sure that water is cool enough. Dā-mite® can overheat if wrong type is used at
the wrong temperature, hole size is beyond diameter shown in literature or mixing water is too warm. Store Dā-mite®
in cool dry place until used. Letting product sit in sun and get hot is poor practice. Also cool off mixing buckets and other
mixing tools prior to use to keep heat away from Dā-mite®.
Let Drilled Holes Cool Off before placing Dā-mite® in them. Cover the area with a tarp or other device
after loading with Dā-mite® to minimize effect of blowouts. Also cover in case of rain to keep product
dry until after Dā-mite®'s chemical reaction is complete.
