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.
Oldest Concrete Street in the United States
The first concrete street in the United States is over 100 years old and is still in use today. As an experiment to improve street conditions in Bellefontaine, Ohio, in 1891, the city council hired George Bartholomew of Buckeye Portland Cement Co. to provide the concrete for an 8-foot segment of pavement next to the hitching posts. The city council was initially skeptical about the durability of the concrete pavement. Two years later, the square surrounding the courthouse was also paved, creating the first concrete street. The construction of the street followed the same techniques that had been developed for sidewalk construction, with slabs formed in 5 ft squares and tar paper between adjacent slabs. A two-layer pavement system was used, with a 4 in base course that had maximum-sized aggregate of 1 1/2 in with a water-cement ratio of 0.60. The top course had maximum-sized aggregate of 1/2 in with a water-cement ratio of 0.45.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.