APPLICATION OF PERVIOUS CONCRETE IN ROAD CONSTRUCTION
This paper presents an overview of the properties of porous concrete, and the advantages of its use in pavement structures. Two mixtures of pervious concrete and a reference concrete mixture commonly used for concrete pavements are prepared and their properties compared: consistency, compressive and flexural strength, porosity and density, dynamic modulus of elasticity, as well as permeability. The possibility of their application in concrete pavements is estimated in accordance with the requirements given in General technical conditions for roadworks. Mixture with a small amount of cement and addition of superplasticizer did not meet minimum porosity and permeability required for pervious concrete. In contrast, a mixture with a higher amount of cement and without the addition of superplasticizer was evaluated as pervious one, but does not have a compressive strength required for road construction. Therefore, it is necessary to direct further research towards improving the compressive strength of mixtures of pervious concrete.
Mix design development for Portland cement pervious concrete in cold weather climates
Portland cement pervious concrete (PCPC) is increasingly used in pavement applications due to its benefits in reducing the quantity of runoff water, improving stormwater quality, enhancing the skid resistance of the pavement during storm events by rapid drainage of water, and reducing pavement noise. In the United States, PCPC typically has high porosity and low strength, which has resulted in limited use of pervious concrete, particularly in hard wet freeze environment (i.e., Midwest and North East of the U.S. and other parts of the world). Improving the strength and freeze-thaw durability of pervious concrete is necessary for increasing use of PCPC in these regions. Included in the following thesis is a literature review that includes the current state-of-practice in PCPC design, construction, and related environmental issues. The purpose of this research is to develop PCPC mix proportions that have not only sufficient porosity for stormwater infiltration, but also desirable strength and freeze-thaw durability. In this research, concrete mixes were designed with various sizes and types of aggregates, binder contents, and amounts of admixtures. The engineering properties of the aggregates were evaluated. The porosity, permeability, strength, and freeze-thaw durability of these mixes were measured. Results indicate that PCPC made with single size aggregate generally has high permeability (greater than 2000 in./hr) but not adequate strength (less than 3000 psi). Addition of a small amount of sand (5% to 7%) and fiber can significantly improve strength and freeze-thaw resistance of the concrete with limited reduction in permeability. Similar to conventional concrete, there are close relationships between PCPC air void content, permeability, and compressive strength. Compaction method and energy has considerable
Museum of Words: The Poetics of Ekphrasis from Homer to Ashbery
As ancient as Homer's lines on the shield of Achilles and as recent as John Ashbery's "Self-Portrait in a Convex Mirror," ekphrasis is the art of describing works of art. Over the ages its practitioners have created a museum of words about real and imaginary paintings and sculptures - a museum that James Heffernan explores in this book. Profoundly ambivalent, ekphrastic poetry celebrates the power of the image even as it tries to circumscribe that power with the authority of the word. This contest is typically gendered: the voice of male speech striving to control a female image that is both alluring and threatening, male narrative seeking to overcome the fixating impact of beauty poised in space. Moving from the epics of Homer, Virgil, and Dante to contemporary American poetry, this book presents a history of struggle between rival systems of representation. Heffernan also shows how this struggle changes. Poets ranging from Ovid to Shakespeare use verbalized depictions of rape to show the violence men do under the "colour" of their words; romantic poetry at once salutes and questions the transcendent beauty of visual art preserved in the newly born public museum. In the modern and postmodern eras, poets contend with all the words generated by museums themselves to regulate our experience of visual art.