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Factors affecting shrinkage Powers; Meininger; and Tremper and Spellman are the three references I have used most to explain the causes of drying shrinkage. Each of them point out that water demand of the separate materials used in concrete is the major determinant of the shrinkage of concrete. I maintain that variations in water demand caused by the separate concrete ingredients has a far greater effect on concrete shrinkage than does the common concern overthe variation in slump.
Powers, and Tremper and Spellman both emphasized the cumulative effect on shrinkage of making poor choices in the selection of material to be used. Powers’ shrinkage results, clarified by Mather in the form shown in Table 1, show the individual and cumulative effects of the most unfavorable versus the most favorable material choices with regard to six factors influencing the amount of shrinkage. Powers assumed a constant water-cement ratio, and concluded: “Wrong choices of alternatives (with respect to volume change) can result in about seven times as much shrinkage as would result from best choices.”
Table 1 below shows that concrete with ¾ in. (19 mm) maximum sized aggregate will shrink about 30 percent more than concrete with 1 ½ in. (38 mm) maximum sized aggregate. But, concrete placing costs may increase slightly when larger aggregate is used. Designers therefore should specify that the maximum sized coarse aggregate be slightly less than ⅓ the slab thickness, with the understanding that the small increase in cost will be offset through lower shrinkage and a more productive floor slab.
If you have questions about your industrial concrete floor contact one of our sales engineers today.
Kalman Floor Company, known for its innovative approach to creating solutions for industrial concrete floor customers, concluded its exhibition and sponsorship of educational and technical discussions at SWANA’s WASTECON®. Kalman installs highly abrasion resistant floors for transfer stations, materials recycling facilities and associated maintenance shops but also works to educate the industry and meet its ever changing needs.
Kalman is currently scheduling presentations about specialty floors for transfer stations and materials recycling facilities which will be beneficial to owners, operators, builders and designers. To arrange for a meeting at your location or to learn more about Kalman systems contact a sales engineer today.
Since 1916, Kalman Floor Company has been the worldwide leader for industrial concrete floor solutions. Kalman Absorption Process® Topping is a highly abrasion resistant concrete floor topping for use in waste management facilities and other industrial environments. In addition, Kalman Seamless Concrete® eliminates floor joints and reduces maintenance costs for its industrial users. A Kalman floor means lower costs and higher productivity.
Solid waste facility floors typically last five years before replacement is required at great expense and operational downtime. At the Monterey (CA) Regional Waste Management District MRF the floor lasted 10 years longer than expected saving time and money through reduced maintenance costs.
In 1996, the Monterey Regional Waste Management District in Marina, California selected Kalman Floor Company to install a 40,000 square foot materials recovery facility (MRF) floor anticipating replacement in five years. In 2001 the Monterey MRF called Kalman to reinstall.
Kalman inspected the floor there was no need for replacement. Over the next few years, Kalman and the owner monitored the floor’s performance. Eight years went by, then 10, 12 and finally after 14 years it was determined to resurface approximately one-third of the facility – there was no need to replace the entire floor or perform a full-depth removal and replacement. The same ¾ inch thick Kalman Absorption Process® concrete topping as utilized originally was used for the resurfacing.
Kalman’s Seamless Concrete® slab and Absorption Process® floor topping stood up to the abuse of tracked vehicles and was still in working order. It is well known in the industry that Kalman’s floors are much more abrasion resistant, more dense and have 80% fewer joints than a conventional concrete floor. These qualities make for a low maintenance, cost effective operation with higher productivity. Contact a sales engineer today to learn how Kalman can help you and your facility.
