A quantitative method for predicting the sound absorption coefficients of various porous highway pavement materials is developed in this research. Types of pavements and material properties of the pavements are considered. Existing models have been evaluated and extended to predict the absorption coefficients of porous materials as a function of their permeability, porosity, and pavement thickness. Experiments are performed on the samples taken from the field and the experimental results are compared with the predicted values of the present method. The effects of several control parameters on the determination of the absorption coefficients are also investigated.
This research intends to develop a method for predicting the sound absorption coefficient of various porous highway pavement materials. Since many of the existing prediction models for acoustic properties and traffic noise still have limitations and problems with accuracy, sound absorption coefficients are measured with the impedance tube method to verify numerical values obtained from the model. Results obtained from the experiment and numerical simulations are compared and presented to reveal the effect and influence of the control parameters.
Abstract. Demolished concrete is found a lot.In developed countries, there is a clever method to dispose such demolished concrete by recycling to get a near quality as natural aggregate in order to reduce natural resources and help concrete waste disposal which is called recycled concrete aggregate (RCA). However, in Bangkok, it is now no strict regulation to dispose demolished concrete. This research studied a feasibility of RCA in Bangkok by simulation which many criteria in the model were assumed to be random parameters; therefore, this research created a model by Monte Carlo Simulation which is differed from other RCA business model simulations that normally use constant parameters. In additions, four conditions were set, first: 100-ton-per-hour constant supplied plant, second: 50-ton-per-hour constant supplied plant, third: 100-ton-per-hour uncertain supplied plant, and fourth: 50-ton-per-hour uncertain supplied plant. The result showed the trend of output rather than 1 simple output thanks to the random inputs. In details, the both constant supplied plant can make a profit, additionally; 100-ton-per-hour plant was more worthwhile than 50-ton-per-hour plant thanks to the economics of scale. On the other hand, for the uncertain supply, 100-ton-per-hour plant was loss, but 50-tonper-hour plant still made a profit.
This paper focuses on the availability of reliable and widely recognized standards for measuring the tyre/pavement noise by determining the existence for a common or certified standard for measuring the asphalt rubber road noise and the possibilities of establishing a common standard or making enhancement to the current standard for accurately measuring the noise. A noise measurement study is conducted using one of many methodologies recognized internationally on both conventional and asphalt rubber road. The noise measurement study is based on the Statistical Pass-by method which is described in detail in the International Standards Organization ISO 11819-1. Certain modifications have been made in order to suit the local environmental condition during the measurement. The most significant modification from the ISO 11819-1 is the distance of the microphone location that is used in the noise measurement from the center of the test road. The ISO 11819-1 stated the microphone position as 7.5m distance from the test road. However, in North America, 15m distance is commonly used. The proportions between noise source dimensions and microphone distance are affected in such a way as to reduce the potential difference between LAmax (maximum sound pressure level) and LAE (Single-event sound exposure level) [2]. Simulations can be done to find out the influence of the microphone distance to the accuracy and reliability of the test measurement readouts besides the advantages and the disadvantages on using both microphone distances from the test road. To further prove the reliability of the study, the results are then analyzed and compared to the predicted noise level using the Traffic Noise Model (TNM) developed by the Federal Highway Administration (FHWA). The FHWA's TNM that computes highway traffic noise is constructed based on the large amount of vehicle noise-emissions database and has been made comparisons to at least five other different model results or real noise measurement study to verify the accuracy of the model.
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