Chapter 1 Basic Properties of Bui lding Materials Section I Composition, Structure and S ucture of Materials 1 . Compos ition of materials 2. Structure and Structure of Materials SECTION II BASIC PHYSICAL PROPERT IES OF MATERIALS 1 . Density, Performance Density and Deposition Density 2. Density and porosity 3. Filling and voidage of materials 4. Hydrophilicity and hydrophobicity of materials 5. Water Absorption and Hygroscopicity of Materi als 6. Water Resistance of Materials 7. impermeability of materials I. Density, Apparent Density and Depo sition Density of Materials (1) Density The number of substances contained in the absolute solid volume per unit of material is density p and international unit kg/m3, which can be calculated by the following formula: Rho =m/V In the formula: m - the quality of the material. V - Volume of material under absolute compaction. (1) Density The calculation of volume V: 1. Material with complete compactness 2. Engineering materials, most of which contain pore 3. For granular materials such as sand and stone (2) Apparent density Apparent density, commonly known as bu lk density, refers to the mass per unit vo lume of material in natural state.Express it in the following form: Rho 0=m/V0 In the formula: m - the quality of the material, V0 - Volume of material in natural state. (2) Apparent density The calculation of volume v0: 1. Regular shape, calculated according to shape size 2. Irregular Shape (1) Processing into Regular Shape Waterproof material film wrapping 3. Bulk Material (3) Accumulation density The mass per unit volume of granular or powdery materials is called bulk density in the state of a ccumulation.Express it in the following form: P'0 = m/V'0 In formula: m - the quality of granular materials. V'0 - The bulk volume of granular materials. Density and porosity The volume of solid material is d etermined by (1) Solid material part (2) Pore part (1) Density The degree to which a solid substance fills the volume of a material. V  0  D 100% V0    (2) Porosity Refers to the proportion of voids in the volume of a materi al (in units of natural state). V0  V V  0   100% P 1   1  V0 V0    3. Filling and voidage of materials (1) Filling rate The extent to which granular materials are filled by particl es in a certain accumulation volume. ' V  0 ' 0 D  ' 100%  100% 0 V0 (2) Void fraction The proportion of pore volume between particles in a cert ain accumulation volume of granular materials.It reflects the compactness of granular materials.It can be used as a basis for controlling aggregate distribution and calculating sand content of concrete. ' P 1  D ' Hydrophilicity and hydrophobicity of materials At this time, the material is hydrophilic. The surface of the material can be wetted by water. It is called hydrophilic material, such as cement concrete, sand, wood, etc. When the material is hydrophobic, the surface of the material can not be wetted. It is called hydrophobic material, such as asphalt. 5. Water Absorption and Hygroscopicit y of Materials (1) Water content The ratio of the quality of water contained in the material to that of the material in the dry state. m1  m W 100% m (2) Water absorption That is, the ability of material to absorb water, expressed in terms of w ater absorption by weight or volume, that is, the percentage of weight or volume of dry material increased after water saturation. Influencing factors: 1. Hydrophilicity of materials (2) Porosity size and pore characteristics of materials (3) Hygroscopicity The property of a material that absorbs moisture in moist air. Moisture content Equilibrium moisture content VI. Water Resistance of Materials The ability of materials to resist wate r damage. Softening Coefficient = Compressive Strength of Mat erial in Saturated Water Absorption/Compressive St rength of Material in Dry State The softening coefficient ranges from 0 to 1, and mat erials larger than 0.80 are generally considered wat er-resistant.Softening coefficient is usually an impo rtant basis for the selection of basic materials. 7. impermeability of materials The impermeability is the material's performance of resist ing the permeability under the action of liquid pressure s uch as water and oil.Material has permeability Qd K AtH Section 3 Basic Mechanical Proper ties of Materials 1 . THEORETICAL STRENGTH OF MATERIALS 2. Strength of materials

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