Many building owners and contractors have reported experiencing project delays while waiting for slabs made with lightweight concrete to dry to the moisture-vapor-emission rate typically required by floor-covering manufacturers (3 pounds per 1000 square feet in 24 hours). Though we couldn't find any data regarding the drying time of lightweight concrete, field experience tells us that lightweight concrete takes longer to dry than normal-weight concrete. To help fill this information gap, Concrete Construction devised a testing program to find out how long it takes lightweight concrete to dry.
The first line of defense in preventing the corrosion of reinforcing steel in concrete is to use good concreting practices. But designers and contractors can add other corrosion-control weapons to their arsenal including corrosion-resistant rebar; corrosion-reducing additions or admixtures; and concrete membranes, coatings, and sealers that block chloride entry. Here's a summary of the options and their relative costs.
More than 441 million cubic yards of concrete will be placed in 2000. And the total in-place concrete cost? A whopping $88 billion dollars. That's up almost 13% from 1999. We gathered cement and concrete statistical data from several sources. Then, with the help of the Portland Cement Association and R.S. Means, a company specializing in estimating and analyzing construction costs, we developed a methodology for estimating the total dollar value of cast-in-place concrete. We extended the methodology to estimate the amount of concrete placed in various building elements, including footings, walls, slabs on grade, columns, and elevated slabs.
Successful contractors seldom follow identical paths. Some find a niche market and fill it better than their competitors. Some spend research money--a lot of it--to develop new building methods that solve old problems. Others take risky jobs that their competitors aren't willing to bid on. And still others follow the time-proven formula of doing their work more efficiently than their competitors can.