For several years the Kansas Department of Transportation (KsDOT) was faced with shear cracks in the concrete girders of two-girder reinforced concrete bridges. A technique that would repair the cracks and increase the girder's shear capacity was needed. Post reinforcement, a repair method that does both of these things, was developed and is now used by the KsDOT. Read more
No single system has yet proven to be suitable for all types of bridge deck overlays. But progress is being made in developing thin polymer concrete overlays that satisfy many requirements: low permeability to water and deicing chemicals; adequate skid resistance; high abrasion resistance; sufficient flexibility; and good bond to existing concrete Read more
The Liberty Mutual Insurance Company's Loss Prevention Department has carried out extensive ergonomic research studies. Read more
Soil-cement is made by thoroughly mixing soil, portland cement and water by one of the ways described in this article. The most practical soils are those that contain not more than 35 percent silt and clay and that are easily pulverized. If more than 4000 cubic yards are to be constructed, the central-plant mixing method proves easy and economical. Read more
Specifications for air-entrained concrete frequently require that air content be held within a percent or so of a target value. But how easy is it to keep air content within this narrow band? Read more
A wheelbarrow is only a wheelbarrow, right? One is as good as the next, right? Wrong. Wheelbarrows are not all the same. Some last longer and some let you last longer using them. Here are a few tips on how to choose a good one and how to use it properly. Read more
A precast concrete barrier wall has been installed at a Somerset, New Jersey satellite earth station to eliminate signal clutter in the dense radio frequency environment of the New York-Philadelphia corridor. Read more
Shoring requirements for the rehabilitation of Spruce Run Bridge in Pennsylvania posed some difficult problems. Eleven badly deteriorated cross beams beneath the deck of the concrete arch bridge were to be cut in half and replaced one half at a time so that the bridge could remain open to traffic. Since the cross beams were supported only by two outside arches, shoring was needed on both sides of the cut and would be subjected to live loads for periods up to 1 1/2 years. Read more
Is there a good general reference that gives standard specifications for concrete work? Sometimes the designer or owner seems to think anybody should know that certain operations are expected, whether the operations have been written into the specificatio Read more
What is microsilica--a cement or an admixture? Where can I get more information about it? Read more
These photographs show the final texture of a slab on grade. The spots shown are distributed throughout the building area. We wonder if the spots are a clue to the trouble we have had with spalling and flaking of the surface in some locations and with sev Read more
How do you avoid the little shapes that look like pointed ovals on concrete surfaces? Would a paint or coating on the plywood forms take care of them? Read more
Job specifications require us to water-cure columns. However, the columns are made with white cement, and water-curing is causing discoloration and staining. It seems to me that I have read that curing at 80 to 85 percent relative humidity is satisfactory Read more
A customer complains that the corner of his driveway next to the street cracked when a heavy truck made a delivery. Read more