Control and Expansion Joints

Control joints are either saw cut or a groove tooled into the concrete.  The reasoning is to place the joints in such a manner to allow the concrete to crack in the joint, remaining unseen.  For 4” thick concrete joints are typically placed on approximately 10’ centers, 15’ centers for 6” thick concrete.  We do our best to place the joints to avoid random cracks.  Random cracks will occasionally occur, it happens.  Concrete cracks when force exceeds strength.  Of course heavy loads will crack your concrete.  We all know that. 

However, most cracks are caused by upward pressure from frost.  When the ground freezes it expands, building tremendous upwards pressure from below.   Areas  where you have heavy, expansive soil (clay) are the worst.  Clay holds more moisture than say sand or gravel.  When it freezes it expands pushing up on the concrete, potentially cracking your concrete.  If you have heavy clay we will offer removing it and placing 4” to 8” of granular fill under the new concrete.  Random cracks though unsightly, do not affect the structural integrity of the slab.  No one in the concrete business, us included, can guarantee your concrete will not crack.

Expansion joints consist of 1/2” wide semi-rigid material that allows the concrete to expand and contract with temperature changes.  It also prevents concrete from bonding to structures such as building foundations.  Foundations, being below the frost line will not move when the ground freezes.  Slabs on grade must be allowed to move with any ground movement, usually it heaves when the ground freezes, settles back in place when the frost goes out.  If a slab on grade is not allowed to move, upward pressure from frost will typically crack the concrete two to three feet from the foundation.  In situations where the concrete cannot be allowed to heave we will pin the concrete to the foundation and place a control joint two to three feet from the foundation to make it crack where it will anyway.

License & Insurance     

All contractors are required to have a Residential Builders license and carry liability insurance.  If they have employees they are also required to carry workman’s compensation insurance.  Typically everyone has on their business card or yellow page ad, “Licensed and Insured”.  Some of our competitors pay their employees in cash or as a sub-contractor.  Workman’s Compensation insurance is based on payroll receipts.  If they pay their employees in cash or as a sub-contractor then they cannot have Workman’s Compensation insurance as they have no payroll.  If an un-insured worker is injured on your property you may be liable for his injuries.  They probably have liability insurance so they can say they are licensed and insured, but in reality the workers may not be insured.   All general contractors and all commercial jobs require a copy of our Workman’s Compensation insurance and will annually have us send them a current copy for their file.  It is not unreasonable to ask your contractor to provide you a copy of their license and workman’s compensation insurance.   You will be protecting yourself.

The Contract     

The contract is extremely important.  Nearly all disputes arise from verbal agreements never put into writing.  To be a contract it must be in writing and signed by both you and your contractor.  Keep your copy on file.  Your contract should clearly spell out exactly what is included in the scope of work.  Size, thickness, reinforcement,  warranty, contract amount, pay schedule etc.  Typically, on smaller jobs we require payment upon completion.  Larger jobs we may require a deposit at the start or after the first pour, with balance due upon completion.  Jobs lasting for several weeks or months we require progressive payments.  The terms should always be clearly spelled out on the contract.  Normally, we do not accept nor do we recommend advanced payments.  (Unless we have to order materials in advance.)  We have all heard about the so called contractor, who after receiving a large advance, left town, never to be seen again. Final payment is typically due upon completion.  Never pay any contractor in full until the work is entirely completed.  If paid in full before the work is completed there will be no incentive for the contractor to finish the work or take care of any potential problems.  Do not allow yourself to be pressured into paying in full before the work is completed.  Also, do not be afraid to ask questions or to make changes prior to signing the contract, after all, you’re the boss.  A good contract protects both you and your contractor.

One more bit of information; since we began in 1978, in the Calhoun County area, no less than 23 concrete construction companies have come and gone.  Most did not last five years.  A percentage of our business is replacing their inferior work.  Of those in the concrete business in 1978 we are the only company still standing.  The rest are gone.  Enough said.

We hope the above information is helpful.  For further information please call us at 269-963-6263. 

Jeff Duckworth at ext. 11      Tom Duckworth at ext. 12

Thank you for considering Two Ducks Concrete to complete your project.  We look forward to working with you.  The following is important information that may be helpful during the bidding and construction process.

Concrete Mix

For exterior concrete we have been using six bag, limestone mix for many years now.  What that means is there are six -  94lb. bags of cement (powder) in every cubic yard of concrete.  This results in a strong, creamy mix that is very easy to finish. 

Limestone is the aggregate in the mix.  The limestone is very dense and does not absorb moisture as readily as other stone.  The reason for limestone is to reduce the chance of popping.  Soft stones absorb moisture and when the temperature drops below freezing the soft stones expand and pop the surface layer of the finished concrete. We use six bag, limestone mix in all exterior work, garages and pole barns included. Basement floors, having ambient temperature always above freezing, we will use an alternate mix design.


Fiber Mesh:  Unless directed otherwise we include wire and fiber mesh in all of our work.  (Fiber mesh only in basement floors.)   Fiber mesh are poly-propylene fibers, approximately 1” long and about the diameter of coarse dog hair.  (Think short pieces of fishing line).  Fiber mesh basically consists of adding 1 to 1 1/2lb. of fibers to each cubic yard of concrete. It is put in the ready mix truck at batching.  Fiber mesh is a great deterrent to random cracking.  However, once the concrete cracks, fiber mesh does nothing to hold the concrete together.  One lb. of fishing line cannot be expected to reinforce 4,000 lbs. (one cubic yard) of concrete.  We typically place saw cut control joints in the concrete to make it crack, (in the joint).  Over time and several freeze/thaw cycles, the concrete is likely to separate at the joints if no other reinforcement is used.  In driveways with fiber mesh only, we have seen as much as 5/8” separation within 5 years.

Wire Mesh:  In all of our work, other than basement floors, we include wire mesh.  Typically, in 4” concrete we use 6x6x10 woven wire mesh.  That means 6”x6” squares by 10 gage wire diameter.  Wire mesh aids in the prevention of random cracks, but more importantly, it keeps the concrete together when it does crack.  (Remember, we cut joints in the concrete so it will crack.)  The concrete can move up and down with freeze/thaw cycles but it cannot separate or shift.

Here is an example of what happens when exterior concrete is poured without wire mesh reinforcement. The two photos show a small patio that was poured in 1998 – only 14 years ago when the house was built.  As the photos clearly show the concrete has shifted and settled to a point where the patio is unusable. 
The current owners say that it has been like that for a number of years. We provided a quote to remove and replace the patio for $3,151.00. At the time of original placement it would have only cost $29.00 for wire mesh. Wire mesh would have prevented this.


Nearly all of our work will include one coat of sealer.  There are a number of sealers on the market.  Most common are “water base” and “oil base”.  Water based sealer is very inexpensive.  We tried it many years ago.  In our opinion we might as well just spray water in the concrete.  We just cannot see any advantage to water based sealer.  We only use a water based sealer when the concrete is to be covered with tile or epoxy.  We exclusively use an oil base sealer to cure and seal your concrete.   Once applied, your concrete will have a thin membrane cover that slows down evaporation, thus slowing down the drying time, curing.  The sealer will penetrate the pores at the surface of the concrete, preventing moisture penetration, thus sealing your concrete.