ABSTRACT
Cracking in concrete bridge decks is a major source of concern for Departments of Transportation throughout the United States. One of the main causes of cracking is drying shrinkage that occurs following the concrete curing period. The goal of this research is to investi-
gate potentially improved behavior of concrete bridge decks by replacing a portion of the portland cement with Type K cement, a hydraulic cement that expands during the early hydration period after setting or by replacing a portion of the fine aggregate with satu-
rated lightweight fine aggregate (LWA) which reduces shrinkage through improved curing by releasing water from the aggregate into the concrete to maintain the internal relative humidity. These three different concretes were tested under the same environmental conditions (i.e. model dimensions and temperature differential). The experiments involved building a scaled bridge deck that is 10 ft. × 7 ft. with a thickness of 8 inches (Fig. 1). Strain and temperature gages were installed on the top and bottom reinforcing mats as well as on the top and bottom surfaces of the concrete slab. The gages were used to measure the shrinkage strain and temperature gradients within the concrete deck for a period of six months. Experimental deck consist of two layers of reinforcement. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig167_1.jpg"/>
From the data gathered, Type K cement showed more initial expansion compared to the control concrete at 7 days. And LWA expands less than the control and Type K mixtures at 7 days. And the Type K has the largest total shrinkage and is comparable to the control. LWA has the smallest total shrinkage over time. (Fig. 2). Average total shrinkage of the top longitudinal reinforcement. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig167_2.tif"/>
