Abstract

Nowadays, using preferences of the natural stones in construction sector especially as floor, interior and exterior siding elements for use in buildings show rising trend every day. When natural stones used as cladding elements for buildings contact with a water source, water moves along the cracks and/or matrix structures by capillary transmission and penetrates to the body. This phenomenon degrades the physical and mechanical properties of rocks over time due to the atmospheric conditions and their chemical content. Therefore, the capillary water absorption coefficient is one of the most important features which must be taken into consideration to determine the using areas of the natural stones. In this study, capillary water absorption coefficients of 118 different natural stone types having different structural and textural features (12 igneous, 29 metamorphic, 77 sedimentary) were determined and related with other rock properties (bulk density, apparent porosity, total porosity, seismic velocity, etc.).

1 Introduction

Natural stone was always been considered the best material for stone based structures and low-cost buildings due to its durability and aesthetic appearance of many different areas such as floor coverings, interior and exterior wall cladding material. Although there are many causes of deterioration, the presence of water has a crucial role since its activity as a solvent of the binding medium (Melo et al. 1999, Poli et al. 2004).

Many building materials, such as natural stones and many artificial construction materials (bricks, mortar, concrete, etc.) are generally composed of a certain volume of empty space in the form of pores, cavities and cracks of various shapes and sizes (Borelli 1999). These empty spaces are primary concern of the material since their volume, size and distribution affect their behavior under various types of weathering phenomena in aggressive environments (acid rain related attack and dissolution, salt crystallization, and freeze–thaw cycles, etc.) when used for structural and ornamental purposes (Cultrone et al. 2004). Since the water is the main weathering agent, open pores and micro-cracks have considerable effects on the fluid storage and circulation capacity within the building material inevitably favouring its deterioration and lowering the mechanical resistance (Sousa et al. 2005). Water can reach through building material by capillary rise of ground moisture, rain, and condensation of air humidity (Arnold 1982). When natural stones, especially used for decorative exterior cladding elements in the buildings, located in different residential areas such as beachfront, industrial zones, etc. contact with rain, surface and/or ground water, it penetrates by capillary transmission and moves along to the body through micro-cracks and/or matrix structures. This natural event is closely related to capillary suction, completely controlled by the pores and cracks in rocks. Therefore, the knowledge of the water movement within the building blocks is of great importance to determine the degradation mechanism of the natural building stones.

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