Black sea coast line is a hazardous region in Turkey especially in winter due to the dominant wave action. Therefore, rubble mound breakwaters used as ship shelters are vital structures especially for the fisherman. Construction of the breakwater requires good quality durable armourstones. Due to the nature of the rubble mound breakwaters, the armourstones with various sizes and types are used in the construction of these structures. The deterioration of these armourstones with time may result in the failure of the breakwater. In this study, various field and laboratory tests suggested in CIRIA/CUR (1991) and Rock Engineering Rating System-RERS (Lienhart 1998) of five armourstones (mainly limestone, andesite and sandstone) are performed. The test results are compared with their site performances in breakwaters and used to evaluate the suitability of the test results. Among the studied stones, the sandstone displays very poor performance. The others are found to be relatively good. Based on the data obtained, it is observed that some of the physico-mechanical parameters of the armourstones are good at predicting the long-term field performance of the armourstones. This paper will discuss the parameters to be used in the durability assessments of the armourstones.
The coast has for many centuries been an area of importance for human development. It is attractive in terms of its flat, fertile land, as base for transport by boat and as a base of fishing (Thomas 1998). However, in order to benefit from the sources of the coast, the protective coastal engineering structures are needed. These structures involve large quantities of quarried rock (armourstone) due to the economical reasons and the demand to build environmentally compatible and suitable structures. In this respect, the use of armourstone (approximately $40–50 per cubic metre) is three times cheaper than the use of concrete blocks ($120–150 per cubic metre), especially in Turkey. Additionally, there is a demand to build environmentally compatible and suitable structures in the world (Mather 1985; Latham 1991; Poole 1991; Erickson 1993; Smith 1999).
The issue of durability of an armourstone relates to the properties of the rock from which it is derived, the environment to which it is exposed, the loads that are applied to it, and the method by which it was extracted from the source and then handled prior to final placement. In time, depending on these properties and the influence of the external forces, the armourstone can loose its quality (Clark 1988; Clark and Palmer 1991; Lienhart 2003; Latham et al. 2006a, b; Ertas and Topal 2006, 2008; Ozden and Topal 2007). This situation directly affects the durability of the coastal structure and in long term the economy of the region. Especially in Black Sea region where in winter harsh climatic conditions with dominant wave influence are observed, these kinds of structures are under great amount of risk. Alapli, Hisaronu and Tarlaagzi rubble mound breakwaters (Figure 1) are good examples of such structures used as ship shelters.
