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|Title:||State-of-the-art report on high-strength, high-durability structural low-density concrete for applications in severe marine environments|
|Authors:||Expanded Shale, Clay, and Slate Institute.|
University of New Brunswick. Department of Civil Engineering.
Innovations for Navigation Projects Research Program (U.S.)
Holm, Thomas A.
Bremner, T. W.
|Publisher:||Structures Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: This report presents an overview of the current knowledge related to high-strength, high-durability structural low-density concrete (compressive strength ≤35 MPa (5,080 psi)) and its application in severe marine environments. Low-density concrete (LDC) is normally made with a manufactured low-density aggregate produced by heating particles of shale, clay, or slate to about 1,200 °C (2,160 °F) in a rotary kiln. At this temperature the raw material bloats, forming a vesicular structure that is retained upon cooling. The individual vesicles are generally not interconnected and produce a dilation of more than 50 percent that is retained upon cooling. This results in the particle density of the raw material changing from about 2.65 before heating to less than 1.55 upon cooling. It is the use of this low-density aggregate that enables the production of high-strength, high-durability structural low-density concrete, which is sometimes referred to by its obsolete term “lightweight concrete.” Since the 1970s, the use of high-strength, low-density concrete (HSLDC) has seen widespread expansion. Coupled with an enhanced high-strength matrix, achievable compressive strength levels for these advanced, structurally efficient concretes have increased by more than 40 percent. Improved structural efficiency has provided economic advantages to thousands of commercial structures and made feasible the construction of offshore marine megastructures in the Arctic and on both sides of the Atlantic Ocean. In addition, innovative bridge design has permitted the functional rehabilitation of hundreds of bridges, where additional lanes were placed on existing girders, piers, and foundations. Extensive laboratory research, coupled with in-depth examination of severely exposed structures, has now essentially eliminated unfounded prejudices toward LDC. The economics and potential future uses depend on how well design professionals can incorporate the unique properties of LDC to meet future building needs.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|