International Journal of Engineering & Technology IJET-IJENS Vol:14 No:03 6 142503-8282-IJET-IJENS © June 2014 IJENS I J E N S Experimental Study of Perforated Concrete Block Breakwater Tamrin, Saleh Pallu, Herman Parung, Arsyad Thaha Abstract-- Perforated concrete block is a new form of breakwater that has similar function like coral reef and artificial breakwater, so the purpose of this research is to investigate how a perforated concrete block works as a breakwater protector structure towards the reduction level of wave height. The result showed that the perforated concrete block is one of breakwater types that could be used to muffle the wave height, and the use of perforated concrete block as a breakwater could reduce the wave height in the protected area and this could be developed into one of economic and eco-friendly breakwaters because the large pores of the concrete block could be used as a home of marine biota and it also reduces the volume of concrete using. Index Term— Perforated concrete block, economic and eco- friendly breakwaters I. INTRODUCTION The damage of coastal area is commonly caused by the high waves that reach the coast which is caused by the bad weather and the damage of coral reef or mangrove that act as a natural wave damper. so, it is required to have a design of coastal protector that has a high security level and economic, thereby, one thing to be considered in the design of coastal protector is the availability of sufficient material for the construction workability. Initially, man thought that the armour stone layer of the breakwater construction required large-sized stone, however as the amount of large-sized stone had decreased, so the breakwater construction is switch into artificial stone that was made according to the concept of the creator that leaded to a new fact that the stability of the breakwater was not only determined by the weight of the stone but it was also highly determined by the interlock of the stone. In the construction development of breakwater itself, this type of breakwater hadn’t overcome the environmental effect, it was also hard to carry out in a region that didn’t have enough quarry, so a new form of wave damper that’s economic, eco- friendly, and could be widely produced is needed to be taken into consideration, so that in this research it is emphasized that an investigation of perforated concrete block needs to be done because the application of perforated concrete block could reduce the volume of concrete using and it is not harmful for the environment because the large pore could act as the home of marine biota. Tamrin is Doctoral Student of Civil Engineer Hasanuddin University, (corresponding author to provide phone: 062-541-7776721; e-mail: fts_tamrin@yahoo.com Salaeh Pallu, is Professor of Civil Engineering, Hasanuddin University, Makassar, email: salehpallu@hotmail.com. Herman Parung is Professor of Civil Engineering Hasanuddin University, Makassar, email: parung_unhas@yahoo.com. Arsyad Thaha Senior lecturer of Civil Engineering Hasanuddin University, Makassar, email: athaha_99@yahoo.com Since Jarlan (1961) had first suggested it, porous breakwater had been widely used to reduce the wave force that reached the front part of vertical wall breakwater (Quinn, 1972). One of the important characteristics of a porous breakwater is that the wave energy will break if it hits the front part of the permeable and porous vertical wall breakwater (Quinn, 1972). In addition to that, the upcoming wave will continue to hit the pore, this will reduce the wave reflection in front of the breakwater structure. Initially, porous breakwater is a breakwater structure that is adopted from caisson type of breakwater whose front wall facing the sea is formed a hole and the back part is made to be permeable, another parameter such as wave height, period, regularity of waves, waves direction, and the depth of water are also taken into account. The wave pressure on the porous wall is less than the solid wall, as Bergmann and Oumeraci (1998) found. A research had also been done by Armono and Hall (2002) for wave transmission in submerged breakwater that was made of artificial reefs/ hollow Hemispherical Shape Artificial Reefs (HSAR). The investigation regarding the porous breakwater had been done by Ariyarathne (2007), in line with the result of the research done by Kondo (1979), Suh, et al. (2001) dan Hagiwara (1984). Rageh dan Koraim (2009) who investigate a vertical wall breakwater with horizontal slots in which result of the research derived a conclusion that a vertical wall breakwater could dissipate the arriving waves up to 50 % with the placement of the breakwater at d/L = 0,25-0,35 where d is the depth of water and L is length of waves. Then, in 2010 Wurjanto et al. investigated the level of effectiveness perforated skirt breakwater (PSB) in the category of long wave and concluded that the higher the value of draft breakwater (s) the smaller the transmission coefficient could get (Kt) or the dissipation energy would be higher. As the Kt coefficient is smaller, the better the breakwater function is, from those results this research will develop three types of breakwater that are made of perforated concrete block called perforated concrete block , so that all of the concrete block will be the waves energy damper and it can be the home of marine biota to proliferate because this type of breakwater is similar to reefs, other than that, this type of breakwater will reduce the run-up to 95 % so that the cost of structure enhancement caused by run-up can be avoided. The method that’s used in this research is 2D laboratory method by using wave flume in the laboratory of Hydraulics and Coastal Engineering Hasanuddin University. The purpose of this research is to derive a perforated concrete block which works effectively to reduce the wave height.