Concrete, the most widely used building material in the world, can be very temperamental in certain weather conditions. Due to its poor tensile strength, concrete is almost always certain to crack, but professionals do their best to reduce the size and delay their appearance. A new app is hoping to reduce the risk of concrete, plastic shrinkage by monitoring weather patterns.
Plastic concrete shrinkage occurs within the first few hours of placing concrete, when the concrete has not yet developed substantial strength. These types of cracks are typically wider and deeper than other early cracks, as they can be between 2 to 4 inches deep and around 1/8 inch wide. In order to prevent plastic cracks from forming, the air temperature, humidity, and wind has to be monitored and adjustments then have to be made. Plastic cracks typically form in hot weather conditions, as the water toward the top of the concrete evaporates very quickly, but can also occur in cold weather situations, when the concrete is much warmer than the air temperature.
The Plastic Crack Risk Calculator, a free created by former superintendent and current professor at Southern Illinois University Mark Grinter, takes the guess work and hassle out of determining plastic crack risk on your projects by pulling weather data from the National Oceanic and Atmospheric Association and comparing that data to evaporation-rate nomographs, which determine how fast water will evaporate. By simply entering your project’s zip code, the app then determines if your site is at a low risk, moderate risk, or high risk for plastic shrinkage for the next 7 days, shown just like in the picture at the top of this article.
The app even lets you set up an account to receive email notifications when weather conditions reach “high risk” levels. Currently, it's only available as a web application which can be accessed from any web browser.
Plastic Crack Risk Calculator | University of Southern Illinois
In September of 2017, OSHA’s new standard on exposure to respirable crystalline silica went into effect in the construction industry. The rule lowered the allowable exposure to the harmful substance to 50 micrograms per cubic meter, a measurement that we’re all familiar with [/sarcasm]. After a full year of enforcement, OSHA is considering making a change to the rule.
Concrete is one of the world’s favorite building materials; it’s strong, simple to mix, and generally widely available. Its dirty little secret has always been centered around one of its main ingredients: cement. To make cement, crushed rock and other ingredients are fed into a kiln that heats the components at temperatures reaching 2,700 degrees Fahrenheit. Those extreme temperatures cause large amounts of carbon dioxide to be released into the air and, combined with the carbon dioxide that’s produced just to burn the fossil fuels to heat the kiln, it makes cement one of the largest producers of greenhouse gases in the world, 5% in total.
Concrete, the construction industry’s building material of choice for hundreds of years, is an extremely tough and durable product. Being such a rigid product, concrete has inherently poor tensile strength, which is its ability to withstand being stretched, as opposed to compressing. This poor tensile strength leads to cracking, which eventually leads to failure. Scientists have been racing to discover the cure to concrete’s cracking problem for years, most notably Henk Jonkers’ bio-concrete, which uses microorganisms to “heal” cracked concrete.
The newest challengers to the material’s flexibility problem are a group of scientists from Nanyung Technological University (NTU) in Singapore. The team calls their product “ConFlexPave” and it not only bends under pressure, unlike concrete, it’s also thinner and maybe even stronger than its traditional brethren.
Concrete, the world’s most widely used construction material, has a giant target on its back and plenty of people want to take a piece of its pie. It’s cheap and strong, which has, so far held off many would-be competitors from getting popular. One of concrete’s major drawbacks and one of its most vulnerable areas is the fact that it’s extremely time consuming and difficult to demolish.
Even though concrete is the world’s most highly used construction material, scientists have failed to understand very important fundamental aspect of the material, until now.
Self-compacting concrete, which does not need to be vibrated to become fully compacted, has many advantages on a job site, such as lower overall costs, faster construction times, no need for a concrete vibrator, and thinner concrete sections. One of the major disadvantages of this type of concrete, however, is that it’s notoriously poor in regards to fire resistance. Traditional concrete solves the fire resistance problem by adding polypropylene (PP) fiber, which allow the concrete structure to stay intact when it comes in contact with fire.
Concrete is great. It’s strong, it’s got a long life, but then, it cracks and everyone is bummed out. Cracking is not only an eyesore, but it leads to structural issues and leaks, among other issues. Back in May, we wrote about a concrete additive that would allow the concrete to “heal” its own cracks and it’s got researchers pretty excited about the possibilities.
Ready mix concrete has been used in construction projects since the first ready-mix factory was built in the 1930s. Since the 1980s, there has been a boom in construction and the use of ready-mix as a building material means that concrete plants have had to work hard to keep up with the ever increasing demand.
If you have ever had to form and pour curbs before you know they can be an absolute pain. Even the extruded curbs have their limitations and come along with a large piece of machinery. The Curb Roller is a new easy solution to the curb problem.
The American Concrete Institute (ACI) has just released a companion guide to the ACI 562-13 Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings. Aimed at contractors, inspectors, owners, and manufacturers, the guide’s main goal is to provide insight into the interpretations and explain the proper use of the ACI 562 principles.