A9R18EC.tmp 21 - property may be estimated by breaking a...

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Prof. M. Fall - University of Ottawa 21 3.2 Rocks Toughness (mechanical strength): Resistance to crushing and breaking . This property may be estimated by attempting to break the rock with a hammer or measuring its resistance to penetration by impact drills. Hardness : Resistance to scratching or abrasion. This property may be estimated by attempting to scratch the rock with a steel knife blade or nail. Soft material will scratch readily while hard materials are difficult or impossible to scratch. Physical properties of rocks (2) 3.2 Rocks Density: Density is the mass per unit volume . Durability: Resistance to slaking or disintegration due to alternating cycles of wetting and drying or freezing and thawing. This property may be estimated by observing the effects of weathering on natural exposures of rock. Physical properties of rocks (3) Crushed Shape : Shape rock takes on after crushing. Bulky-angular fragments provide the best aggregate for construction. This
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Unformatted text preview: property may be estimated by breaking a sample of the rock into smaller pieces. . Chemical stability: Resistance to chemical reactions that lead to the deterioration of the materials . 3.2 Rocks Physical properties of rocks (4) Surface Character : Bonding characteristics. Excessively smooth, slick, non-absorbent aggregate surfaces bond poorly with cement. Excessively rough, jagged or absorbent surfaces are undesirable because they resist compaction, placement and require excessive cementing material. Visually inspect the rock surface and feel the surface texture to estimate this property. 3.2 Rocks Physical properties of rocks (5) Lecture outline Chap. 1: Geological Materials and Processes 1. Introduction 2. The Earth 3. The materials 4. Weathering and erosion of the materials 4 Weathering and erosion …. . 4.1 Weathering of materials 4.2 Erosion of materials 4.3 Soil formation...
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