1. Introduction
Recently, improvements in the standard of living in industrial area require the establishment of a convenient residential environment in order to enhance the quality of living. To achieve such an environment, it is necessary to effectively reduce or prevent various environmental prob- lems occurring in and around residential areas. These include air pollution, water pollution, soil contamination, noise, vibration, ground settlement, offensive odors, etc. From among these, traffic noise created by the development of new roads due to the recent rapid increase in vehicle ownership has become a serious environmental problem. Therefore, to overcome this problem, a type of concrete needs to be developed that cannot only create visual harmony with the surrounding natural environment but also aid in the reduction of environmental load such as noise. From this view point, focus is turned toward the development of multi-functional
porous concrete having water and air permeability, good sound absorption ability, etc., by artificially forming con- tinuous porosity using coarse aggregate of single size rather than the more traditional fine aggregate [1–4].
In addition, of the 39 million tons of construction wastes generated from construction sites due to urban renewal projects and expansion of social infrastructures, waste concrete amounts to 24 million tons [5]. Such waste concrete is used as subgrade and landfill material and recycled into bricks for sidewalk pavement. However, due to the insufficient recycling facilities and difficulty in securing good quality waste concrete for recycling, more than 90% of waste concrete is used as subgrade material. Therefore, considering our current domestic situation involving the shortage of natural aggregate resources, a study on the use of the waste concrete as an alternative aggregate with a view to effective utilization of the resource and environmental protection is in urgent need.
Thus, in order to examine the effective use of recycled waste concrete aggregate and its applicability to porous concrete as a sound absorption material, this study examined
the physical and mechanical properties of porous concrete
according to the recycled aggregate content and target void
ratio and analyzed its sound absorption characteristics using the impedance tube method and the reverberation room
method.