Dominant weathering profiles of granite in southern Peninsular Malaysia S.V. Alavi Nezhad Khalil Abad a, ⁎, E.T. Mohamad a , I. Komoo b a Department of Geotechnics and Transportation, Faculty of Civil Engineering, Universiti Teknologi Malaysia (UTM), Skudai 81310, Johor, Malaysia b Universiti Malaysia Terengganu, Malaysia abstract article info Article history: Received 9 April 2014 Received in revised form 12 October 2014 Accepted 20 October 2014 Available online 29 October 2014 Keywords: Dominant weathering profile Granite Joint spacing Joint trace length Corestone Tropical region One of the most important challenges in the study of slope stability, foundations, and excavation of rocks is to understand their weathering states. This issue is more important in tropical climates, where severe weathering produces thick weathering profiles with different sequences of weathering. Thick weathering profiles are nor- mally classified or graded, based on field observation, geological studies, and the material properties of the rocks. This paper presents the results of an extensive study of changes in the geological and morphological char- acteristics of granite in a tropical region due to severe weathering. A total of 40 panels of rock exposure were studied in four active granite quarries located in Johor, southern Peninsular Malaysia. The proposed dominant weathering profiles of granite are mainly based on the sequences of weathering zone, topography and geological conditions, joint characterization, and the dominant color of rock material. In addition, two additional weathering subzones are introduced in the completely and the highly weathered zones based on the presence of corestones (boulders). It is believed that the proposed dominant weathering profiles can contribute to engineering design and the classification of weathered granitic rock in the tropical region. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Identification of dominant weathering profiles is important to engi- neering works related to weathered rock masses (Moye, 1955; Ruxton and Berry, 1957; Anon, 1995; Komoo, 1998; Raj, 2010). In engineering fields (such as civil or mining activities) rock mass weathering profiles are useful for the preliminary stages of design and planning (Verma and Singh, 2009; Jahed Armaghani et al., 2013; Kalatehjari et al., 2013). Weathering effects may vary from place to place because of rock types and structure, topography, rate of erosion, and regional cli- mate variations. Weathering is more intense in tropical regions due to heavy rains and hot and humid climatic conditions, which develop weathering effects to greater depths than elsewhere (Komoo, 1995). Weathering profiles in tropical regions have specific features such as abrupt changes between different weathering zones and the presence of fresh rock blocks (corestones) within a matrix of severely weathered rock material, which are difficult to predict. Despite the mentioned complexities, the recognition of the dominant weathering profiles of granite in these regions is still in its early stages, and only few studies have been carried out on it (e.g. Komoo, 1985; Zhao et al., 1994; Raj, 1998). Therefore, to provide a basic understanding of the complex behavior of weathered granite in tropical regions, more studies are needed to determine the dominant weathering profiles and their characteristics. Based on the dominant profiles, preliminary site investi- gation for any civil engineering projects such as slope, foundation and excavation can be more effectively carried out. In addition, the domi- nant weathering profiles can be used later to develop a typical weathering profile for a rock mass. Dearman (1974, 1976) played an important role in the classification of weathered rock masses by suggesting that for complicated conditions weathering zones could be mapped into the rock mass based on differ- ent weathering zones. Several attempts have been conducted to give a complete description of rock weathering based on the type of rocks and the associated engineering problems (Moye, 1955; Ruxton and Berry, 1957; Dearman, 1976; Matula, 1981; Murphy, 1985). Generally, the classification systems of engineering geology have been qualitative descriptions of weathered rock masses, which are typically related to granitic rocks (Arel and Önalp, 2004). Komoo (1987) proposed that the dominant mass weathering profiles for granitic rock in Peninsular Malaysia are types A and B. The main difference between these types is the distribution of corestones in different weathering zones. Moreover, abrupt changes of weathering zones were only reported in type A. In addition, a material weathering profile was proposed for granitic rock in tropical regions by Komoo et al. (1991). This profile is based on the discoloration of material, textural preservation, mineral composition, and the strength or friability of material. Zhao et al. (1994) studied Bukit Timah granite in Singapore to develop a weathering profile and determine a method for estimating the strength indices of granitic rock mass. This profile included both material and mass descriptions. Lee and De Freitas (1989) reviewed the schemes that have been introduced for the classification of weathered granitic rocks. They also discussed the most common problematic issues in the classification Engineering Geology 183 (2014) 208–215 ⁎ Corresponding author. Tel.: +60 197915178. E-mail address: vankaseyed2@live.utm.my (S.V. Alavi Nezhad Khalil Abad). http://dx.doi.org/10.1016/j.enggeo.2014.10.019 0013-7952/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Engineering Geology journal homepage: www.elsevier.com/locate/enggeo