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  • Author: R. Kowalski x
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Application of a Sclerometer to the Preliminary Assessment of Concrete Quality in Structures After Fire

Abstract

The paper presents a description and results of a study focused on the applicability of the sclerometric method to the preliminary assessment of concrete quality in structures after fire. Due to the high thermal inertia, concrete has non-uniform properties in the heated element cross-section. The greatest reduction of concrete compressive strength occurs on the heated surface. When assessing a structure after a fire, it is particularly important to determine the thickness of the damaged external concrete layer. Reinforced concrete beams exposed to high temperature on one side (a one-way heat transfer in the cross-section) for 0 (unheated element), 60, 120, 180 and 240 minutes were examined. A significant decrease of the rebound number on the elements heated surface was observed, depending on the heating duration. The obtained values of the relative rebound number reduction were comparable to the values of relative compressive strength decrease (determined on the basis of temperature) of concrete situated 15 mm from the heated surface.

Open access
Investing In Industrial-Technology Parks In City Development - A Cost-Benefit Analysis

Abstract

Cities are growing both quantitatively and qualitatively. The quantitative development of a city can be identified with the spatial expansion and changes in the function of certain areas. The city's development, therefore, requires the reconstruction of the spatial layout, but also needs certain capital expenditures, as exemplified by industrial-technology parks (ITPs). ITPs are a combination of the infrastructure function and performance which enable the exchange of information between scientific organizations and entrepreneurs. They are, therefore, a pro-development component of the urban development strategy. The aim of the study is to identify and quantify selected costs and benefits, as well as estimate the effectiveness of establishing certain parks from the point of view of local government units.

Industry parks and technology parks are diverse entities. Their general characteristics and types, based on a review of domestic and foreign literature, are presented in the first part of the work justifying the study. The second part introduces the industrial-technology parks which are present in Poland. In the third part of the study, the specificity of assessing the effectiveness of an industrial-technology park is described. Finally, the fourth part includes an analysis of investing in selected industrial-technology parks; the analysis consists of three phases: the identification of industrial and technological parks, the verification of the industrial-technology park with the legal and practical definition, and cost-benefit analysis. According to the Polish Agency of Information and Foreign Investment (PAIiIZ), industrial-technology parks focus primarily on filling the space with commercially efficient companies using modern technologies, attracting investment and creating jobs. All of these factors are taken into account in the analysis. The analysis is carried out according to the methodology of cost-benefit analysis (CBA) of investment projects.

Despite the diversity and dynamics of the structural features of the parks, the analysis confirms that the investment of public funds in industrial and technological parks is generally efficient in terms of socio-economic development.

Open access
Thermal Bowing of Reinforced Concrete Elements Exposed to Non-Uniform Heating

Abstract

The paper presents the test description and results of thermal bowing of RC beams exposed to non-uniform heating at high temperature. Bending of a non-uniformly heated element is caused by free thermal elongation of the material it is made of. The higher the temperature gradient, the greater the bending. In the case when an element is exposed to load and high temperature simultaneously, apart from free bending also deformation of the RC element may occur, which is caused by the decrease of the concrete or reinforcing steel mechanical properties. In order to examine the contribution of the deflection caused by thermal bowing to the total deformation of the bent element with a heated tension zone, an experimental study of freely heated (unloaded) beams was performed. RC beams were heated: (1) on three sides of the cross-section or (2) only on the bottom side. Deflection of elements loaded by a substitute temperature gradient was calculated using the Maxwell–Mohr formula. The test results show that deflection of freely heated RC beams (caused by the thermal bowing phenomenon) can be 10 to 20% of the total deflection of loaded RC beams with a heated tension zone.

Open access
Mineral carbonation of metallurgical slags

Abstract

Due to increasing emissions of greenhouse gases into the atmosphere number of methods are being proposed to mitigate the risk of climate change. One of them is mineral carbonation. Blast furnace and steel making slags are co-products of metallurgical processes composed of minerals which represent appropriate source of cations required for mineral carbonation. Experimental studies were performed to determine the potential use of slags in this process. Obtained results indicate that steel making slag can be a useful material in CO2 capture procedures. Slag components dissolved in water are bonded as stable carbonates in the reaction with CO2 from ambient air. In case of blast furnace slag, the reaction is very slow and minerals are resistant to chemical changes. More time is needed for minerals dissolution and release of cations essential for carbonate crystallisation and thus makes blast furnace slags less favourable in comparison with steel making slag.

Open access
Research on a Laboratory Technique for Tire-Pavement Noise Assessment of Asphalt Mixes

Abstract

Communication noise is classified as one of the pollutions for the current environment. Experimental techniques to measure tire-pavement noise generation from asphalt pavements in the laboratory have been limited. A series of experiments were conducted on six different asphalt mixtures to determine if Purdue University’s Tire-Pavement Test Apparatus (TPTA) could be used to overcome these limitations. The procedure produced samples with low tire-pavement noise; however, the air void contents of the samples were higher than designed. Despite these difficulties, the sample preparation technique and the TPTA testing protocol were shown to offer an effective approach for quick laboratory assessment of tire-pavement noise characteristics of hot mix asphalt pavements at a substantially reduced cost compared to field testing.

Open access