February 1971 Table of Contents

Problem Clinic About Those Marine Borers...

What information do you have concerning the ability of certain marine borers to penetrate concrete? Is it true that these creatures secrete an acid which is capable of dissolving concrete? Read more

Problem Clinic Gap-Graded Concrete

We are bidding a project which calls for gap graded mixes. What are the advantages and disadvantages? Read more

Problem Clinic Plastic Shrinkage Can Produce Cracks

What causes concrete to crack within several hours of the time it is placed? We did a driveway recently and within three hours cracks began to appear over most of the surface. The cracks range from a few inches in length to several feet, and some appear t Read more

Problem Clinic Slab Pumping

What is meant by the term pumping when used in respect to a pavement defect? Read more

Problem Clinic Cement and Aluminum

What are the chemical reactions between portland cement and aluminum that cause: (1) Hydrogen gas (as in pumping through aluminum pipes)? (2) Expansion of the aluminum (as in buried conduit)? Does the latter occur when calcium chloride is not present? Wha Read more

Problem Clinic Ready Mixed Concrete Plant Certification

How many r/m/c plants are now certified under the program of the National Ready Mixed Concrete Association? Read more

Problem Clinic Carbonation Puzzle

Some time ago an article in Concrete Construction warned against the use of unvented heaters for protecting concrete during cold weather construction. It was stated that the exposure of plastic concrete to carbon dioxide produced soft, chalk-like surfaces Read more

Problem Clinic High Density Concrete

Do you have any information concerning the relationship between the cost of concrete and the density? Read more

Close X