Is all concrete the same?
There are many types of concrete mixtures available on the market, each designed to fulfill a specific need. It is important to identify which type of concrete will provide you with the best results for your driveway, walkway or hardscape application.
With the increased variety of projects in the construction and engineering industries, it is not surprising that manufacturers are constantly testing and bringing to market new and innovative concrete mixtures. The constant drive to make it better, make it stronger, make it last longer, keeps manufacturers on their toes.
Concrete differs based on the type of materials used, the ratio of mix, the method of processing, the additives used in the mixture, and the form of hydration reaction. Concrete is a science, and the measure of which determines if your concrete installation will be a success.
When considering a driveway or sidewalk replacement, there are a few types of concrete to consider. Regular Concrete is a classic mix of sand and other aggregate that is bonded together with a fluid cement that hardens over time. Regular Concrete is designed to withstand pressures that range between 1450 and 5800 psi. The higher the psi, the stronger the concrete, and the more capable it is to withstand weight.
When receiving estimates from a masonry or concrete company, make sure to ask about the type of concrete they will be using, and how they will prepare the ground below, to ensure your driveway or walkway will withstand the test of time.
Part of the integrity of your concrete installation is the uniformity of the subgrade composition and the type of materials used, as this will provide an even slab thickness, and prevent slab settlement and structural cracking. Soft and pliable materials in the base should be removed and gravel or crushed rock should be installed in its place.
Although a lot more expensive, high-performance, air-entrained concrete mix offers a solution to driveways that are subject to heavier vehicles and traffic, freeze/thaw conditions, and deicing chemicals. This specialized concrete can save you money in the long run if cracks and imperfections are a pet peeve. When speaking with your contractor make sure he uses concrete with at least a 4000psi rating, an air content around 6 percent (this will allow for expansion within the concrete during freeze-thaw cycles), and a water-cement ratio below 0.50.
Properly installed concrete is not only determined by the type of concrete used. Correctly placed joints, not more than 10 feet apart, and one-fourth deep, will help prevent random cracking. Using steel reinforcement when preparing the driveway will provide additional structural capacity. Reinforcement does not prevent cracking, but it will keep the driveway together it that occur. When speaking with your contractor, ask that they include the details of the ground preparation and a jointing plan as part of his written proposal.
The thickness of the concrete is the most important factor in determining your driveways structural capacity, even more so than the strength of the concrete. Depending on the application, driveways should be installed with at least 4 inches to 8 includes of concrete. Walkways should be installed with at least 3 inches to 4 inches of concrete.
Other factors determining a successful installation, include proper drainage of water away from existing structures, and the proper curing technique. Curing of the concrete is the final step of your installation and one of the most important processes, as it will increase your concrete’s resistance to weather, and prevent premature surface defects.
The proper finishing of your concrete installation is also an important factor in the overall appearance of your new driveway. Finishing the concrete is typically a three-step process which includes, leveling off the concrete with a screed to achieve a uniform surface, floating the concrete with a wood or magnesium bullfloat, and broom finishing the top to improve traction, unless your driveway or walkway calls for stamping, or applying another decorative finish.
Stamped Concrete provides an alternative way to finish your driveway or walkway. Stamped Concrete stands out, as it is typically designed to resemble stone, brick, tile or even wood through the use of stamp molds and coloring, which provide texture to the concrete surface. Stamped Concrete is very popular, and is used by landscape architects to accentuate outdoor remodeling projects.
Other types of concrete include Lightweight Concretes that are used to protect steel structures, used in long span bridge decks, and even as building blocks. High Density Concrete contains crushed rocks as coarse aggregate. This type of concrete is most commonly used in atomic power plants and other similar structures because it provides good protection from all type of radiations.
Glass Concrete has grown in popularity as recycled glass can be used as aggregates in concrete. This type of concrete increases the aesthetic appeal, while providing an environmentally friendly use of the recycled product. Glass Concrete also provides long-term strength and better thermal insulation.
Precast Concrete is another type of concrete which is cast into molds either in a factory or at a job site. However, they are not used in construction until they completely set and hardened in a controlled condition. Some of the examples of Precast Concrete are; precast poles, fence posts, concrete lintels, staircase units, concrete blocks and cast stones.
Most of the mega concrete projects are carried out using Pre-stressed concrete units. During the mixing and the placing of the concrete, tensioned bars are placed firmly and held from each end of the structural unit. Once the concrete sets and harden, the structural unit will be put in compression. Pre-stressed concrete units are used for the construction of bridges, heavy loaded structures, and warehouse buildings.
When hiring a masonry contractor, make sure to ask for a written agreement that details the job, the cost and the payment schedule, and make sure to get a guarantee in writing. Be wary of contractors, that try to ask for full payment before doing any work.
The risks of hiring an unlicensed and uninsured contractor are not worth the initial cost savings. Utilizing an unlicensed and uninsured company can leave you and your family exposed to fraud, inadequate workmanship and potential harm. Typically these companies do not carry General Liability or Workers Compensation insurance because of the expense which they cannot afford to carry. As they are not licensed, no one is checking.
Giuseppe Noto Stellar Home Improvement Inc.
(646) 352-3453 www.stellarhi.com