Browsing by Author "Golias, Michael"

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    Absorption and desorption properties of fine lightweight aggregate for application to internally cured concrete mixtures
    (ELSEVIER SCI LTD, 2011) Castro, Javier; Keiser, Lucas; Golias, Michael; Weiss, Jason
    Recently, substantial interest has developed in using fine lightweight aggregate for internal curing in concrete. Mixture proportion development for these mixtures requires the specific gravity, water absorption, and water desorption characteristics of the aggregate. This paper presents results from a recent study in which the properties of commercially available expanded shale, clay and slate lightweight aggregates (LWA's) were measured. This research measured the time-dependent water absorption response for the lightweight aggregate. The results indicate that a wide range of 24 h water absorption values exist for commonly used fine lightweight aggregates (e.g., absorption between 6% and 31%). Desorption was measured and it was found that between 85% and 98% of the 24 h absorbed water is released at humidities greater than 93%. These properties can be normalized so that they can be efficiently used in proportioning concrete for internal curing. Normalized plots of absorption and desorption demonstrate benefits for a single function that describes a large class of expanded shale, clay, and slate aggregate for use in internal curing. (C) 2011 Elsevier Ltd. All rights reserved.
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    Can Soy Methyl Esters Improve Concrete Pavement Joint Durability?
    (2012) Golias, Michael; Castro, Javier; Peled, Alva; Nantung, Tommy; Tao, Bernard; Weiss, W. Jason
    Although many concrete pavements provide excellent long-term performance, some pavements (primarily in the Midwest) have shown premature deterioration at the joints. This premature deterioration is a concern because such deterioration can shorten the life of pavements that are otherwise functioning well. Previous work has hypothesized that these joints may be susceptible to preferential fluid saturation, which can lead to freeze thaw damage or chemical degradation. This work examines the use of soy methyl ester polystyrene (SME-PS) blends as a method to reduce the rate of fluid ingress into the pore system of the concrete and thereby make the concrete more resistant to deterioration. SME-PS is derived from soybeans and has demonstrated an ability to reduce fluid absorption in concrete when used as a topical treatment. A series of experiments was developed to evaluate the effectiveness of various dosage rates of SME-PS for increasing concrete durability at pavement joints. The experiments show that SME-PS reduces fluid ingress, salt ingress, and the potential for freeze thaw damage. As a result of the positive experimental results, the Indiana Department of Transportation is conducting field trials that use SME-PS on concrete pavements that are beginning to show signs of premature deterioration with the expectation that SME-PS will extend the life of the joints and thereby reduce maintenance cost and extend the life of concrete pavements.
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    The influence of the initial moisture content of lightweight aggregate on internal curing
    (ELSEVIER SCI LTD, 2012) Golias, Michael; Castro, Javier; Weiss, Jason
    This paper explores the potential for manufacturing internally cured concretes with lightweight aggregate (LWA) that has different initial moisture contents prior to mixing: oven-dry, 24 h pre-wetted, and vacuum saturated. Results show that when LWA is used in an oven-dry condition it can absorb water from the paste prior to set which will be returned to the system as internal curing water. When mixture proportion adjustments are properly made to account for the water absorbed by the aggregate before setting, the mixture can provide internal curing benefits. These beneficial aspects include increased hydration which leads to higher compressive strength, reduced water absorption, and reduced electrical conductivity (permeability). Further, these benefits include reduced autogenous shrinkage and a lower propensity for early-age cracking. (C) 2012 Elsevier Ltd. All rights reserved.