1. CE 212 - SummerDr SaMeH1 Properties of Materials & Strength 1 (CE 212) [4] Associate Professor of Environmental Eng. Civil and Environmental Engineering Department Faculty of Engineering Majma’ah University s.mohamed@mu.edu.sa faculty.mu.edu.sa/smohamed/SaMeH 2016- Summer Semester Sameh Saadeldin Ahmed

2. Density, Specific Weight, Porosity Solidity, Void ratio, Hydro- and Thermal Properties CE 212 - SummerDr SaMeH2 Chapter (2b) Properties of Materials

3. Some Physical Properties 1. Density 2. Specific Weight 3. Solidity and Porosity 4. Voids ratio 5. Hydro- Properties of Materials 6. Thermal Properties of Materials CE 212 - SummerDr SaMeH3

4. 1. Density Apparent Density Test of Sand 1) Weight the dried sample of 300 g ( m 0 ) and put it in the volumetric flaks filled with half flask of cooled boiled water. 2) Shack volumetric flask to the specimen stir fully in water to expel pebbles, block it with a stopper and let the flask stand for about 24 hrs. And then use the burette to add water until the water surface is as high as the scale of the bottleneck. Fasten the stopper and clean the water in the outside surface of the flask. Weight the mass ( m 1 ). 3) Pour the water and the specimen and clean inside and outside surfaces of the flask. Fill the flask with cooled boiled water (the temperature difference is 2C max.). Fasten the stopper and clean the water in the outside surface of the flask, Weight the mass ( m 2 ).

5. 1. Density – cont. The apparent density of the specimen should be defined by the following formula (accurate to 10 kg/ m 3 ) = - Where: m 0 is the moisture- free mass (g); m 1 is the total mass of specimen, water and the flask (g); m 2 is the total mass of water and volumetric flask (g); α 1 is the correction coefficient for the influence of temp. Test Table: Correction coefficient for the influence different temperatures and Apparent Density of Sand 2524232221201918171615 Water Temp © 0.0080.0070.006 0.005 0.004 0.003 0.002 α1α1

6. 1. Density – cont.

7. True Density (ρ) Is the dry mass per unit volume of a substance under absolute compact conditions (homogenous materials). It is defined by: True density ( ρ ) = = The volume under absolute compact conditions refers to the solid volume without the volume of inner pores (C). In the measurement of the density of a porous material, the material is grinded into powder at first, the powder is dried to a fixed mass. And then the solid volume is measured by Lee’s density bottle. The finer the powder is grinding, the more the real size will be. Thus the density value is more correct.

8. 1. Density – cont.

9. For most materials, bulk density is less than true density, but for liquids and materials like glass and dense stone material, these parameters are practically. Properties like strength and heat conductivity are greatly affected by their bulk density. Temperature and pressure are two factors, which affect the density, for instance, when we increase pressure the volume of object decreases, which enhances the density of that particular object. Similarly, if we increase the temperature of an object, its density decreases as the volume increases

10. 1. Density – cont. True density, Apparent Density, Bulk Density, and Porosity of common building materials Porosity (%) Bulk Density (kg/m 3 ) Apparent Density (kg/m 3 ) Density (gm/cm 3 ) Name --- 78507.85 Steel 0-0.3---2500-28502.6-2.9 Granite 0.5-3.0---2000-26002.6-2.8 Limestone ---1400-1700---2.6-2.9 Gravels and Pebbles ---1450-1700---2.6-2.8 Ordinary sand 20-40---1500-18002.5-2.7 Sintered Clay Bricks ---1300-1700---3.0-3.2 Cement 5-20---2100-2600--- Ordinary Concrete 2-4---2300-2400--- Asphalt Concrete 55-75---400-8001.55 Wood

11. Specific Weight (γ) : also known as the unit weight, is the weight per unit volume of material. Where: γ = specific weight (kN/m3) ρ = density of the material, kg/m 3 g = gravity (m/s 2 ) CE 212 - SummerDr SaMeH11 2. Specific Weight

12. Specific weight can be used in civil engineering to determine the weight of the structure designed to carry certain loads while remaining intact and remaining within limits regarding deformation. It is also used in fluid dynamics as a property of the fluid (e.g., the specific weight of water on earth is 9.80 kN/m3 at 4 o C ). CE 212 - SummerDr SaMeH12 2. Specific weight

13. Porosity (η) : the volume of the pores of a substance, to the total volume of rock. η = volume of pores / volume of rock Porosity is indicative of other major properties such as, bulk density, heat conductivity, and durability. Dense materials, which have low porosity, are used for constructions requiring high mechanical strength, on other hand, walls of buildings are commonly built of materials featuring considerable porosity. CE 212 - SummerDr SaMeH13 3. Solidity and Porosity

14. Solidity : refers to the degree how the volume of a material is packed with solid substances. Which is the ratio of the solid volume to the total volume. It defined by: The relationship between solidity and porosity can be expressed as: D +n = 1 Both solidity and porosity reflects the compactness of materials. Porosity and characteristics of pores ( including size and connectivity, distribution, etc., ) affect the properties of materials greatly; CE 212 - SummerDr SaMeH14 3. Solidity and Porosity –cont.

15. Generally, for the same material, the lower the porosity is, the less the connected pores are; Thus: -The strength will be higher; -The water absorption will be smaller; -The permeability and frost resistance will be better; But - The thermal conductivity will be grater. CE 212 - SummerDr SaMeH15 3. Solidity and Porosity –cont.

16. Voids ratio (e) : is defined as the ratio of volume of voids ( V v ) to the volume of solid ( V s ) The relationship between voids ratio and porosity can be expressed as: If an aggregate is poured into a container of any sort it will be observed that not all space within the container is filled. CE 212 - SummerDr SaMeH16 4. Voids ratio

17. To the vacant spaces between the particles of aggregate the name voids is applied. Necessarily, the percentage of voids like the specific weight is affected by the compactness of the aggregate and the amount of moisture which it contains. CE 212 - SummerDr SaMeH17 4. Voids ratio

18. 5.1) Hydrophilicity and Hydrophobicity Hydrophobicity: comes also from the Greek word Hydro (water) and phobicity ( fear). Hydrophilicity: comes also from the Greek word Hydro (water) and Philicity ( friendship). The evaluation of Hydrophobicity and Hydrophilicity is made through water contact angle measurements. CE 212 - SummerDr SaMeH18 5. Hydro-properties of Materials

19. Hydrophilicity and Hydrophobicity CE 212 - SummerDr SaMeH19 5. Hydro-properties of Materials When angle θ is smaller than or equals to 90 o θ<90 o the material is Hydrophilic, such as wood, brick, concrete, and stone. The attractive force between materials molecules and water molecules is stronger than the cohesive force between water molecules. So the materials can be wetted by water.

20. CE 212 - SummerDr SaMeH20 5. Hydro-properties of Materials When angle θ is bigger than 90 o θ>90 o the material is Hydrophobic, such as asphalt, wax, and plastic. The Hydrophobic materials are moisture-proof and waterproof, usually used for water resistance materials or the surface treatment for the hydrophilic materials in order to reduce water absorption and improve impermeability.

21. 5.2) Hygroscopicity: is the property of materials to absorb water in the air. It can be expressed by water content or moisture content. The water content is defined as the ratio of the mass of water to the mass of sample. CE 212 - SummerDr SaMeH21 5. Hydro-properties of Materials

22. 5.3) Water absorption: Denotes the ability of material to absorb and retain water. It can be expressed as percentage in weight or of the volume of dry material. CE 212 - SummerDr SaMeH22 5. Hydro-properties of Materials Where: M 1 = mass of saturated material (g). M = mass of dry material (g). V 0 = volume of material including the pores (mm 3 ).

23. CE 212 - SummerDr SaMeH23 5. Hydro-properties of Materials Water absorption by volume is always less than 100% The properties of building materials are greatly influenced when saturated. The ratio of compressive strength of material saturated with water to that in dry state is known as coefficient of softening and describes the water resistance of materials. For materials like clay which soak readily it is zer o. Whereas for materials like glass and metals it is one.

24. 5.4) Water Resistance: Water resistance is the ability to maintain its original properties when material is affected by water in a long term. CE 212 - SummerDr SaMeH24 5. Hydro-properties of Materials Where: K R is the softness coefficient of a material ; f b is the compressive strength of a material in water saturation state (Mpa) f g is the compressive strength of a material in dry state (Mpa)

25. CE 212 - SummerDr SaMeH25 5. Hydro-properties of Materials K R varies between 0 (clay) -1 (steel) ; Materials with K R less than 0.8 should not be recommended in the situations permanently exposed to the action of moisture.

26. 5.5) Impermeability: Impermeability is the ability of a material to resist the water pressure or the infiltration of other liquids. It is expressed by permeability coefficient which is defined by: CE 212 - SummerDr SaMeH26 5. Hydro-properties of Materials K is the permeability coefficient (cm/s); Q is the volume of water seepage (cm 3 ); d is the thickness of specimen (cm); A is the seepage area (cm 2 ); t is seepage time (s); H is the water head (cm).

27. CE 212 - SummerDr SaMeH27 5. Hydro-properties of Materials Permeability coefficient K reflects the rate of water flowing in a material. The bigger K is, the faster the flow rate of water and the weaker the permeability is. The impermeability of some materials such as (concrete and mortar) can be expressed by impermeable level which represented by the maximum water pressure resisted by materials. for example P6, P8, P10, P12 reveal that the material can resist 0.6 MPa, 0.8 Mpa, 1.0 MPa, and 1.2 Mpa water pressure without water seepage.

28. 5.6) Forest Resistance: Denotes the ability of water-saturated material to endure repeated freezing and thawing with considerable decrease of mechanical strength. CE 212 - SummerDr SaMeH28 5. Hydro-properties of Materials The reason for freeze damage is a volume expansion (about 9%) caused by freeze of the water within material’s pores. Thus the walls of the pores experience considerable tensile stresses and may even fail. The pore walls will crack, the porosity will increase and the strength will decrease. The more the freeze-thawing cycle, the greater the damages there will be. Forest-resistance is expressed by forest resistance level such as F25, F50, F100 and F150.

29. 6.1) Thermal Conductivity The property of material that indicates its ability to conduct heat is known as thermal conductivity. CE 212 - SummerDr SaMeH29 6. Thermal Properties it is expressed by the coefficient of thermal conductivity λ, which is defined by: Q is the conducted Heat quantity (J) d is the thickness of a material (m) t is the time for the Heat transfer (s) A is the Heat transfer area (m 2 ) T 2 -T 1 is the temperature difference of the two materials (K) λ is the coefficient of thermal conductivity [(W/mK)]

30. CE 212 - SummerDr SaMeH30 6. Thermal Properties The smaller the value of λ is, the better insulation the material has. The coefficient of thermal conductivity of a metallic material is bigger than of non-metallic material. The bigger the porosity is, the higher the coefficient will be. The thermal conductivity coefficient of a material containing water or ice increases dramatically because the coefficient of water and ice is bigger than that of air.

31. 6.2) Thermal Capacity thermal capacity is a property of material to absorb heat when it is heated and to release heat when it is cooled. CE 212 - SummerDr SaMeH31 6. Thermal Properties It is defined by: Q is the heat absorbed or released by a material (J) T 2 -T 1 is the temperature difference before and after heating or cooling (K) C is the specific heat of a material [J/(g.K)] m is the mass of a material (g)

32. CE 212 - SummerDr SaMeH32 6. Thermal Properties The specific heat, also called specific heat capacity, is the measure of heat energy that a substance in a unit quality absorbs or releases when the temperature increases or decreases by 1 K. (1K = C +273.15) The bigger the specific heat is, the better the stability of the indoor temperature will be. Thermal conductivity coefficient and specific heat should be known when thermal calculations are conducted to buildings.

33. 6. Thermal Properties Thermal Conductivity Coefficients and Specific Heat Capacities Specific Heat Capacity C [J/(g.K)] Heat Conductivity Coefficient λ [W/m.K] Substance Specific Heat Capacity C [J/(g.K)] Heat Conductivity Coefficient λ [W/m.K] Substance 1.460.05 Fiberboard for thermal Insulation 0.38370 Copper 0.880.04 Glass Wool board 0.4655 Steel 1.300.03 Foam 0.802.9 Granite 1.000.025 Sealed Air 0.881.8 Ordinary Concrete 4.190.60 Water 0.840.55 Ordinary Clay Bricks 2.052.20 Ice 1.630.15 Pine (Cross Striations)

34. 6.3) Thermal Deformation thermal deformation is the property of substance to expand with heat and contract with cold, it is called heat deformation. CE 212 - SummerDr SaMeH34 6. Thermal Properties It is expressed by linear expansion coefficient α, which is: ∆L is the expansion or contraction value of a specimen (mm) ∆t is the temperature difference (K) α is the linear expansion coefficient of a substance (1/K) L is the length before heating or cooling (mm)

35. CE 212 - SummerDr SaMeH35 6. Thermal Properties The bigger the linear expansion coefficient α is, the greater the thermal deformation will be. The thermal deformation is determined to civil engineering; In a large-area or large-volume concrete project; temperature cracks can be caused if the expansion tensile stress is beyond the tensile strength of concrete. In a large-volume construction work, expansion joints are set to prevent the cracks caused by thermal deformation. Petroleum asphalt will have a brittle factures when temperature drops to a certain extent.

36. 6.4) Flame Resistance flame resistance is the property of substance not to flame in case of contacting with fire in the air. CE 212 - SummerDr SaMeH36 6. Thermal Properties 6.4.a) Non-flammable Materials: are the ones that cannot be fired, carbonized or slightly burned when contacting with fire or high temperature in the air (bricks, natural stone, concrete, mortar, and metal). 6.4.b) Fire-retardant Materials: are the ones that hard to be burned or carbonized and stop burning or slightly flaming immediately when leaving fire (gypsum board, cement, asbestos board, and plaster).

37. CE 212 - SummerDr SaMeH37 6. Thermal Properties 6.4.c) Flammable Materials: are the ones that are ignited or flame immediately and continue to burn or slightly flame when leaving fire (plywood, fiber board and wood). Reference: Haimei Zhang, Shuo Ma, Yanyan Wu, “Building Materials in Civil Engineering “ Woodhead Publishing Limited, 2010.

38. CE 212 - SummerDr SaMeH38 Units J = Joule K = Kelvin 1 K. (1K = C +273.15) Pa= Pascal N=Newton to make a mass of 1 Kg go faster at a rate of 1m/ S 2

39. End of Chapter 2 CE 212 - SummerDr SaMeH39