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Title: How to Reduce Settlement Cracking in Reinforced Concrete

Author(s): Muzai Feng, Rouzbeh Khajehdehi, David Darwin, and Eman Khalid Ibrahim

Publication: Web Session



Appears on pages(s):



Date: 11/13/2018

Settlement of concrete is a phenomenon that takes place during early hours after concrete is cast. This can be a problem in structures having top bars where the settlement of the fresh concrete around the reinforcement can cause cracking and/or a weak plane right above the reinforcement. Settlement cracking is particularly important to durability of bridge deck structures because it takes place right above the reinforcing bars that will let de-icing agents a direct pathway to reinforcement level and start of the corrosion. In this presentation first a brief overview of existing research on the topic of settlement (or settlement cracking) of concrete will be given. Development of a test method by University of Kansas to evaluate the settlement cracking of reinforced concrete specimens will be explained and the effectiveness of use of different crack-reduction technologies on settlement cracking will be evaluated. These technologies include the use of shrinkage reducing admixtures, internal curing (IC), SCMs, combination of IC and SCMS, synthetic fibers and use of rheology modifying admixtures. Results of these tests show that many of the technologies that reduce shrinkage cracking also reduce settlement cracking. Results of these tests will be analyzed in more detail to identify the factors affecting settlement of concrete.