Nick Griego & Sons FAQs
What are some of the environmental benefits of concrete?
Aside from concrete being long lasting and durable, there are many other benefits to concrete including ease of design and construction; appearance versatility; economic benefits such as reduced energy costs; and environmental benefits.
What is the initial cost difference between concrete versus asphalt?
The initial cost difference between constructing with concrete versus asphalt depends on a variety of design elements such as, but not limited to pavement thickness, soil conditions, design criteria and/or equipment use for placement. For projects less than 50,000 square feet, the initial cost may be less or equal to that of asphalt, provided that both systems have the same structural number (SN). The savings, when using concrete, are: the cost of mobilization of heavy equipment necessary to achieve high-density requirements for the subgrade and the limerock base; the cost of base materials and labor for proper placement; and the cost of cut/fill to compensate for the base layer.
Can you control cracking problem in concrete paving?
Certainly! Cracks typically occur during the first 24 to 48 hours when stresses created by the natural drying shrinkage exceed the tensile strength of concrete. One can control a cracking problem in concrete paving by having a uniform subgrade support, performing proper curing immediately after final finish and placing proper control/contraction joint spacing within 12 hours after placement.
Also known as expansion joints, isolation joints separate slabs from fixed objects like walls and columns so that slabs can move independently of other parts of the structure. Isolation joints permit vertical and horizontal movement between the slab and any fixed objects that the slab abuts. The isolation joint material must be compressible and thick enough to allow such movement.
What is the proper spacing for control/contraction joints?
Having proper joint spacing is vital to long-term performance of your concrete pavement. The rule-of-thumb for maximum joint spacing is 30 times the pavement thickness converts in unit of feet (i.e. Thickness = 4.0 inches; Joint Spacing = 120 inches or 10 feet). The maximum spacing for pavement thickness exceeding 6 inches is 15 feet. Keep panels as square as possible; the maximum length to width ratio is 1.25:1. The best practice for designers is to layout predetermined spacing on the plan prior to construction.
When is the proper time to saw-cut control/contraction joints?
Do not wait until the next day! Contraction joints can be sawed as early as 3 hours after placement, but do not exceed the 12th hour. To determine the proper time of saw cutting, operation should not cause surface deformation or raveling along the edges of the joint. An early-entry, dry-saw machine is recommended.
Why and when should I cure my concrete pavement?
Concrete does not gain proper strength by drying out. The hardening of concrete depends on a chemical reaction or the hydration of cement. The hydration process depends on temperature, time and moisture. The amount of shrinkage and curling of slabs can be reduced by performing proper curing. Curing should start as soon as placing and finishing is completed-the surface will not be damaged.
Can I eliminate welded wire mesh for my concrete parking lot? What's the alternative?
Yes! According to the American Concrete Institute (ACI) 330R-01 Guide for Design and Construction of Concrete Parking Lots, "The sole function of the distributed steel reinforcement is to hold together the fracture faces if cracks form." Moreover, "When pavement is jointed to form short panel lengths that will minimize intermediate cracking, distributed steel reinforcement is not necessary. The use of distributed steel reinforcement will not add to the load-carrying capacity of the pavement and should not be used in anticipation of poor construction practices." When the purpose is to minimize plastic shrinkage and settlement cracking, use synthetic fibers. They reduce bleeding, increase impact and shatter resistance, as well as abrasion resistance.
How can I ensure proper density around drainage structures?
One of the common failures which can occur on a concrete parking lot is around drainage structures. Inadequate compaction of backfill material around these structures can result in loss of support for the pavement. In lieu of using compacted backfill, an option is to use a controlled density fill material (also known as Controlled Low Strength Material/ CLSM) or flowable fill. This will prevent settlement of the slab.