Wikipedia.org BUILDING STONES Chapter 4 Materials of Construction-Building Stones 1
What is Stone? Stone is a concretion of mineral matter. Used either as a; Construction material, Manufacture of other construction materials. Stone has high strength, durability and nice appearance. Materials of Construction-Building Stones 2
Uses in Construction Building walls, bridges, dams, Road surfacing, (blocks or crushed rock) Aggregate in concrete. Materials of Construction-Building Stones 3
Stone / Rock These are often used synonymously. However; Rocks are made up of one or more minerals which have definite chemical compounds. These minerals usually have crystalline structures, but some consist of a natural noncrystalline structure. Stone is used to define quarried or small pieces of rock for a specified function such as a building block, a paving block, etc. Materials of Construction-Building Stones 4
Geological Classification of Rocks Igneous, Sedimentary, Metamorphic. Materials of Construction-Building Stones 5
Igneous Rocks outreach.canterbury.ac.nz Formed by cooling and solidification from a molten state Materials of Construction-Building Stones 6
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Igneous Rocks 1. Intrusive Rocks: Slowly crystallized within the earth 2. Extrusive (volcanic) Rocks: Rapidly crystallized due to fast cooling on the surface of the earth 3. Pyroclastic Rocks: Formed after sudden eruption, include volcanic ash composed of fine amorphous particles. Materials of Construction-Building Stones 8
Sedimentary Rocks Sediments are transported, deposited and solidified through pressure exerted by overlying material or by the action of natural agents. stloe.most.go.th Materials of Construction-Building Stones 9
Metamorphic Rocks Formed by gradual changes in the structures of either igneous or sedimentary rocks caused by the action of heat, pressure, water etc. stloe.most.go.th Materials of Construction-Building Stones 10
Important Rock Types used as Construction Material Wikipedia.org Materials of Construction-Building Stones 11
Granite Coarsely crystalline intrusive rock. Contains silica in the form of quartz, feldspar and mica Red, pink, gray, brown Strong, hard, nonporous Used in flooring, interior or exterior wall facing, column facing, stair treads. beg.utexas.edu Materials of Construction-Building Stones 12
Basalt Finely crystalline extrusive rock which occurs as lava sheets. Dark colored, Basalt is also a hard and strong rock, but it is likely to somewhat porous and fractured. beg.utexas.edu Materials of Construction-Building Stones 13
Limestone Sedimentary rock composed mainly of CaCO 3 Limestones containing considerable amount of magnesium carbonate are dolomitic limestones. Used as: concrete aggregate, raw material in cement production, flux in the produciton of pig iron.. mii.org Materials of Construction-Building Stones 14
Travertine Sedimentary rock, composed mainly of calcium carbonate Off-white, gray, light to dark tan Used as: interior decorative stone, due to its pleasing texture Materials of Construction-Building Stones 15
Sandstone Sedimentary rock made of grains of sand cemented and compacted to form a solid rock. SiO 2 & Al 2 O 3 ; cementing material may either be calcium carbonate or clayey matter. Used as facing material Alpinequarries.com Wikipedia.org Materials of Construction-Building Stones 16
Marble Metamorphosed limestone, more crystalline and harder than limestone. Great range of colors Hard and strong rock which can hold polish well. May weather easily, used for interior work such as wall, column facing, flooring Wikipedia.org Materials of Construction-Building Stones 17
Slate Metamorphosed clay SiO 2, Al 2 O 3, Fe 2 O 3, K 2 O, MgO Black, green, gray, red and purple.. Can be separated into thin sheets with smooth surfaces. Tough, strong and nonabsorptive. Used for flooring, interior or exterior wall facing, window sills, and roofing. Materials of Construction-Building Stones 18
Production of Building Stones Quarrying: Overburden of soil or inferior stone is first removed from the surface. Large blocks of stone ( 1X1.5X3 m) are cut, loosened at the bottom by wedging and removed by cranes. Shaping and finishing: Large blocks of stone are cut to desired shape and given whatever degree of finishing is desired. Materials of Construction-Building Stones 19
Selection of Building Stones Durability, appearance and cost are important parameters. Durability, temperature changes, average humidity of the atmosphere, fire and abrasion resistance (related to hardness) are important. Materials of Construction-Building Stones 20
Durability The durability of a stone is its ability to resist weathering action, chemical attack, abrasion, frost, heat and other service conditions. Both durability and the strength of a stone are affected by the texture, mineral composition, chemical and physical characteristics. Materials of Construction-Building Stones 21
Strength (a) the mineral composition (b) the rate of cooling (grain size) of the igneous rocks (c) the manner of formation and the size of the component crystals of sedimentary rocks (d) the type and degree of metamorphism of metamorphic rocks. Therefore, the strengths of stones show great variations. (from low values up to 3500 kgf/cm 2 ) Materials of Construction-Building Stones 22
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Strength The compressive strength of stone is important to support foundations or in stone masonry. However, the compressive strength of most stones is sufficiently high to be used in structures. The strength of stone masonry is much less than the strength of stone itself, the exact strength depending on the width of the joint and the type of mortar used. The tensile and the flexural strength of stone are much lower than its compressive strength. Materials of Construction-Building Stones 24
Porosity & Water Absorption Porosity V of V pores total The water absorption capacity of stone is related to its porosity (amount of permeable pores) Weight of water absorbed Absorption, % x100 Dry weight of stone The presence of permeable pores also affects the frost resistance of stones. When water gets in the pores and freezes, the ice exerts some internal pressure. Alternate freezing and thawing processes cause cracking of stones. Materials of Construction-Building Stones 25
Strength vs Absorption of Stone Materials of Construction-Building Stones 26
Coefficient of Expansion Stones expand upon being heated. However, unlike most materials, they do not return to their original volume when cooled after heating. They show a small amount (0.02 to 0.04%) of permanent swelling. The coefficient of expansion of a stone affects its expansion upon being heated, and contraction when cooled. Materials of Construction-Building Stones 27
Physical Properties of Dry Building Stones Ultimate Compressive Str. (MPa) Weight (g/cm 3 ) Porosity (%) Coeff. Of Expansion (10-6 / O C) Granite 100-210 2.50-2.83 0-1 5.58-7.56 Marble 70-180 2.56-2.72 0.2-0.6 3.6-10.08 Limestone 30-140 2.23-2.69 0.3-2.0 1.8-8.46 Sandstone 50-140 2.13-2.56 5-28 0.4-4.5 Slate 50-210 2.75-2.83 0.1-0.7 12.6-18 Materials of Construction-Building Stones 28
Fire Resistance The cause of damage in stone under high temperatures is the disintegration that occurs because of the internal stresses due to unequal expansion of unequally heated portions of the stone. Limestone suffers little until a temperature of somewhat above 700 C is reached, at this point it decomposes (CO 2 is driving off). Sandstones suffer least from fire if they are dense and non-porous Granites and marbles suffer great from fire. Materials of Construction-Building Stones 29
Caststone.org Cast or artificial stone is a masonry product made of concrete. The surface may include granite, quartz, marble, etc. The textures may be smooth, polished, colored or uncolored. Synthetic stone is made from minerals and a polyester plastic binder. For example, synthetic granite is produced using approximately 50% fine grained granite, 30% fine silica sand and 20% polyester resin. Synthetic marble is produced by combining approximately 80% fine silica sand, 2-3% pigment and 17-18% polyester resin (no marble!). Materials of Construction-Building Stones 30
Example Two rock samples A and B have the following characteristics Dry weight of sample (g) Water absorption by capillarity (g) Absorption capacity (g) Unit weight (g/cm 3 ) Specific gravity Rock A 875 12 41 2.5 2.9 Rock B 800 10 35 2.3 2.85 Calculate the capillary porosity, permeable and impermeable pore percentages of the two rocks. Which rock is more permeable? For Rock A V=875/2.5=350 cm 3 a) capillary porosity=12 cm 3 /350=0.0344=3.44% b) permeable porosity=41/350=0.117=11.7% c) total porosity=1-(2.5 g/cm 3 /2.9x1 g/cm 3 )=0.14=14% Since total porosity=permeable porosity+impermeable porosity d) impermeable porosity=0.14-0.117=0.023 (2.3%) For Rock B V=800/2.3=348 cm 3 a) capillary porosity=10 cm 3 /348=0.0286 b) permeable porosity=35/348=0.100=10% c) total porosity=1-(2.3/2.85)=0.2=20% d) impermeable porosity=0.2-0.1=0.1 (10%) Permeabilty of rock is controlled by its permeable porosity since A rock has a higher permeable porosity, it is expected that it will have higher permeability. Materials of Construction-Building Stones 31