By admin Construction • • • • • • 0 Comments

Hot Weather Concreting: How to Avoid the Problems that it Presents

The Perils of Concreting During
Hot Weather And How To Avoid Them

Hot weather concrete pouring can cause a myriad of problems. Many people think it is just about the heat itself but there is more to it than that. Many factors affect the quality and success of concreting during hot weather conditions. Hot weather, as defined by ACI 305R is any combination of the following:

  • High ambient temperature above 90 degrees
  • High concrete temperature
  • Low relative humidity
  • High wind speed
  • Solar radiation

The heat is not the problem as concrete cures through hydration and not temperature. However, when the concrete becomes hotter than 77 degrees, it speeds up the hydration timing. If the concrete isn’t hydrated properly, it will be weak, crack easily and be more susceptible to damage from freezing and thawing. Construction crews must prepare for hot weather concrete placement.

Ways to Prepare for Pouring Concrete in “Hot Weather”

  • Crews should avoid pouring the concrete during the hottest part of the day. Tracking hour by hour temps can assist with this determination. It is also wise to avoid extreme temperature changes. Pouring concrete on a hot day when followed by a cool night can cause thermal cracking to ensue.
  • A team of workers should be available to ensure that the work is finished quickly and efficiently. Truck delivery should occur early in the day and a group of laborers ready to start immediately. Check for any potential delays so that the task will be completed in a timely manner.
  • Sunshades, windbreaks or mist fogging can be used to protect and slow down the process of the concrete curing too quickly.
  • Extended set additive, moderate heat cement and blended cements can provide solutions to pouring concrete in difficult conditions.
  • Keeping concrete in the shade before pouring or using an evaporative retarder may help as well.
  • Once the water is added to the mix, reduce the mixing time.
  • Ice or cold water can be added to the mixture to cool down the concrete. Cold water can reduce the heat of the concrete by about 10 degrees and ice by approximately 20 degrees.
  • If a slab is being poured, putting cool water on the sub-grade is another neat trick.
  • Control-joints can be spaced closer together to aid in strengthening.
  • Steel Fiber Concrete can be used to make slabs to add after walls and roofs are built out. Adding steel fiber to concrete has advantages and disadvantages so do your homework before choosing this method.
  • Extreme weather conditions may require the infusion of liquid nitrogen into the mixers. This solution can be costly as there are concerns about damage to blades and precautions must be taken.
  • There are several curing methods that can be used. Understanding these methods directly impacts how successful your curing process is.  Concrete companies will want to have a plan ahead of time as to the correct method for each individual situation and to follow through with recommended procedures.

Setting concrete in difficult situations is a complicated process. However, with a little research and a lot of preparation, a concrete job can have favorable results.

By admin Paving • • • • • • 0 Comments

What Temperature Should You Pour Concrete?

Concrete can be poured at any time when the temperatures have been above 40 F for over 72 hours. Moderate temperatures make the placement crew’s job easier as it sets up at a good pace, allowing ample time for edging, jointing, troweling and curing. In some instances, it can be placed when temperatures are lower but special additives are used, and heating may also be required. The other factors that can affect concrete pouring include wind speed, humidity levels, and the temperature of the sub-base which is the surface you will be pouring your concrete on.

Pouring your concrete in cold weather

In regards to concrete, cold weather is anything below 40ºF. Here are some tips for pouring concrete in cold weather;
  • Should the sub-base be frozen thaw it with heaters. Alternatively, you could pour the concrete on Styrofoam material as it helps sustain the temperature in the concrete.
  • Order for concrete products that are designed to cure promptly. Cold weather concrete is capable of resisting thawing and freezing effects as they have air entrained voids.
  • Ascertain that the concrete you order for has a low slump also known as a drier mix to minimize bleed water. You can use a vacuum or squeegees to rid the concrete of bleed water. This will help decrease the setting time.
  • You could use hot water to mix the concrete or use extra cement, that is, 100 lbs per cubic yard of concrete to create a heated reaction.
  • Once you have successfully poured your concrete, maintain its temperatures at 50ºF for a minimum of 3 days to a maximum of 7 days. This can be achieved through the use of heated enclosures or an insulating blanket.
  • If you are going to make use of a heated enclosure, ascertain that it is weatherproof and windproof.
  • Once you determine that the concrete is well set, you can remove the insulating blanket or the heated enclosure to allow the concrete to air dry.

Pouring your concrete in hot weather

  • Hot temperature in regards to concrete pouring is anything above 77ºF. Here are some tips for pouring concrete in hot weather;
  • Avoid pouring the concrete when it’s too hot to avoid temperature-related issues. You can do so either early in the morning or late in the evening.
  • You can erect shades along with wind barriers to protect the poured concrete from crusting or stiffening. Crusted concrete is highly susceptible to plastic shrinkage, crazing, and cracking.
  • Have a few people help you with the mixing process. Prolonged mixing only results in increased temperatures. You can add ice to the water mix to cool the temperature of the mixture.
  • You can dampen the sub-base to help minimize its temperature before pouring your concrete.
  • You can control the evaporation after pouring through the use of wet burlap, polyethylene sheets, waterproof paper, and windbreaks.
  • Should the weather be extremely hot, you will need to observe continuous moist curing for the next couple of days until the concrete is dry.

Finally, note that it is not advisable to place concrete when temperatures exceed 100 F, as it can flash set and there won’t be enough time for proper finishing.

By admin Asphalt Paving • Paving • • • • 0 Comments

Should You Pave with Asphalt or Concrete?

When paving your driveway, it pays off to use the best materials possible. Whether you’re installing a new driveway, conducting driveway repair or are resituating your front yard’s layout, you should know the differences between asphalt and concrete installations.

If you don’t want to use low-end gravel or brick pavers, asphalt and concrete are your best bet. Each has advantages, but each is particular to different housing, driveway, traffic and lifestyle situations. Before picking a material, check out the differences below.

 

Concrete

When paving with concrete, you’ll have the benefit of a quick dry time. While both concrete and asphalt need to ‘cure’ before they’re driven on, concrete may take longer to dry. Concrete driveways utilize cement as a main building material.

The Positives

In general, cement driveways last longer than tar driveways. Tar is softer than cement, and it degrades quicker. With proper maintenance, a cement driveway can last ages. Additionally, a concrete drive is aesthetically pleasing if a homeowner wants a natural-looking home extension. Plus, concrete delivery is normally quick.

Concrete is an easy material to work with, and it can be manipulated to exist in a number of different finishes. Concrete can be tinted, stained and revised to display a number of colors. It can also be colored on a section-by-section basis, giving a driveway unique patterns. Concrete is a fantastic mold, too. Homeowners can etch, engrave and stamp various designs into concrete, making their driveway incredibly unique.

The Negatives

While cement is incredibly flexible, it’s frequently expensive to use as a material. Concrete takes much longer than cement to dry, so it isn’t a great option for homeowners in need of a quick sidewalk repair, driveway repair or installation.

Because concrete is comprised of sand and minerals, it’s more susceptible to cracking. It doesn’t expand well, and it can break if the temperature rises, or falls, rapidly. Salt, used for melting ice, is a good investment if you live in a cold area.

 

Asphalt

Like concrete, asphalt does take time to dry before it can be driven over. A lot of homeowners in high-temperature climates use asphalt for its temperature resistance. While asphalt may get hotter than cement, it’s a great choice for homeowners seeking long-lasting options while being practical.

The Positives

Asphalt is easily poured, so it’s a great option in terms of installation flexibility. Tar is generally cheaper than cement, and it offers a great bang-for-your-buck experience. Because tar expands and contracts with heat contact, it’s an excellent installation option if you live in a hot area.

A lot of homeowners use asphalt to create a seamless driveway-to-road look. Asphalt, for many, offers a more “classic” design than typical asphalt installations.

The Negatives

Asphalt is a more limited than concrete. Because it needs to be rolled and compressed, unique finishes are difficult to maintain. Until recently, asphalt color variations were limited. Still, some homeowners may not like the lack of design diversity with asphalt.

Asphalt needs to be resealed every three to five years, too. It also needs to be resurfaced. Fortunately, asphalt repairs are generally easier to conduct than concrete repairs.

 

So, Which Should You Choose?

While both materials are viable installation options, you should select the material most conducive to your area’s environment. If your driveway experiences rapid temperature shifts often, stick with asphalt. If you live in a cold area, consider installing a cement driveway.

An asphalt driveway can cost between four and seven times as much as a concrete driveway. While a concrete street needs little maintenance over 20 to 30 years, an asphalt driveway may need to be resurfaced in as little as 15 years. Paving with concrete means you’ll face less maintenance. However, concrete may not last as long.

At the end of the day, measure the costs. Then, pick the driveway repair, installation or replacement option healthiest for your wallet—and for your family.