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Building stones

Introduction tothe use of building stonesRequirements for building stoneStandardsGeology and geological classification of rocks according to EN12670

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Natural stonesDimensionstonesBuilding stones

Dimension stone

Natural stone or rockselected and finished to specific sizes or shapes

- sliced, cut, drilled, ground, or other- color, texture and pattern, and surface finish

durability- Endurance and capability to maintain its essential and distinctive

characteristics of strength, resistance to decay, and appearance

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The major producers:Brazil, China, India, Italy,and Spain,9-20 Mtons/year, eachPortugal produces 3 Mton/year

USGS, 2007 U.S. dimension stone productionwas 1.39 million tons valued at $275 million,granite production was 453,000 tons valued at$106 million I($ 233/ton)limestone 493,000 tons valued at $93.3 million($189/ton)

One of the oldest forms of “business”http://all-that-is-interesting.com/wordpress/wp-content/uploads/2012/03/oldest-structures-megalithictemples4.jpg

Main use of building stonesFoundation and WallItemsFacing and ArchitecturalItems• cladding materials• slabs and stones, stairs and

landings, parapets etc.Building Items: Elementsof stairs, landings,parapets and guard rails

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Road Construction Items

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Curb stones• intended to separate roadways from

sidewalks;Paving blocks—used for pavements;Cobble stone—used to reinforceslopes of earth works and banks ofwater basins

armored stones

Bridges and underground structures

Slabs and stonestypically fromigneous andsedimentary rocks

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Heat and Chemically Resistant Items

• Non-weathered rocks.• For high temperature working

conditions,- chromite, basalt, andesite and tuffs- protection against acid- granite, syenite, and silicious stones

• Resistance against alkalis- Limestones, dolomites, marble and magnesite

show excellent

.

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Qualities of building stones

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Architectonical, esthetics• Appearance and structurePhysical propertiesEconomicCost of production and transportationMarket demand

Uniform and “homogeneous” rocks with predictable properties andappearance

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Stength• function of mineralogy, macro- and microtexture

Weight• density of most common minerals (and many rocks) 2.5-2.8 ton/m3

• porosity (proportion of vugs, cavities, microfractures)• For certain structures such as dams, retaining walls, etc. heavier stones are used

• arches, vaults, domes, etc. light stones may be the choice

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Weight• density of most common minerals (and many rocks) 2.5-2.8 ton/m3

• porosity (proportion of vugs, cavities, microfractures)• For certain structures such as dams, retaining walls, etc. heavier stones are used

• arches, vaults, domes, etc. light stones may be the choice

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Hardness

• function of mineralogy, macro- and microtexture• typically measured using Mosh-scale• (average) mineralogical composition

• Dory’s testing machine• Measurement of rocks

• important for floors, pavements, aprons of bridges, etc.• Grinding resistance, skidding in pavements and floors

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Toughness

• The measure of impact that a stone can withstand• Resistance to vibratory or moving loads

For toughnessA steel hammer of 20 N is allowed to fall axially in the specimen.The blow at which the specimen breaks represents thetoughness of the stone.

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Porosity and Absorption

- Primary porosity• e.g. in volcanic rocks• depends on the composition, cooling time and

- Secondary porosity• most pores in sedimentary rocks are secondary (dissolution of cement)• microfractures

- Water can fill the pores by• Infiltration, capillary suction, chemical bonding i.e. absorption

- In cold conditions water freezes, expands, and causes cracking- Water enables chemical reactions and weathering

• dissolves minerals, transports dissolved constituents by advection and diffusion

- Permissible water absorption for some of the stones is given in Table 3.5.

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EN 1936 NATURAL STONE TEST METHODS. DETERMINATION OF REAL DENSITYAND APPARENT DENSITY, AND OF TOTAL AND OPEN POROSITY

• apparent density (ρb)o ratio between the mass of the dry specimen and its apparent volume

• apparent volumeo volume limited by the external surface of the specimen, including any voids

• volume of the solid parto difference between the apparent volume of the specimen and the volume of the voids (open and closed

pores)• real density (ρr)

o ratio between the mass of the dry specimen and the volume of its solid part• open porosity

o ratio (as a percentage) between the volume of the open pores and the apparent volume of the specimen• total porosity

o ratio (as a percentage) between the volume of pores (open and closed) and the apparent volume of thespecimen

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Relevant standards

[1] EN 1925, Natural stone test methods – Determination of water absorption coefficient by capillarity.

[2] EN 1926, Natural stone test methods – Determination of compressive strength.[3] EN 12370, Natural stone test methods – Determination of resistance to salt crystallisation.[4] EN 12371, Natural stone test methods – Determination of frost resistance.[5] EN 12372, Natural stone test methods – Determination of flexural strength under concentrated load.[6] EN 12407, Natural stone test methods – Petrographic examination.[7] EN 12440, Natural stone - Denomination criteria.[8] EN 13161, Natural stone test methods – Determination of flexural strength under constant moment.[9] EN 13364, Natural stone test methods – Determination of the breaking load at dowel hole.[10] EN 13373, Natural stone test methods – Determination of geometric characteristics on units.[11] EN 13755, Natural stone test methods – Determination of water absorption at atmospheric pressure.[12] EN 13919, Natural stone test methods - Determination of resistance to ageing by SO2 action in thepresence of humidity.[13] EN 14066, Natural stone test methods – Determination of resistance to ageing by thermal shock.[14] EN 14146, Natural stone test methods – Determination of the dynamic modulus of elasticity (bymeasuring the fundamental resonance frequency).[15] EN 14147, Natural stone test methods – Determination of resistance to ageing by salt mist.[16] EN 14157, Natural stone test methods – Determination of the abrasion resistance.[17] EN 14158, Natural stone test methods – Determination of rupture energy.[18] EN 14205, Natural stone test methods – Determination of Knoop hardness.[19] EN 14231, Natural stone test methods – Determination of the slip resistance by means of thependulum tester.[20] EN 14579, Natural stone test methods – Determination of sound speed propagation.[21] EN 14580, Natural stone test methods – Determination of static elastic modulus.[22] EN 14581, Natural stone test methods – Determination of linear thermal expansion coefficient.

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EN 14231 Slip resistance test bypendulum apparatus

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Geology of building stonesMain types of rocks• Igneous, Sedimentary, MetamorphicThe key controls of physical properties rocks• Mineralogy

- Minerals comprise rocks- Naturally occurring substances with a crystal lattice

• Texture- The size, shape, and arrangement of the grains (for sedimentary rocks) or crystals

(for igneous and metamorphic rocks)- Microscopic to macroscopic features

• Structure- Large scale features (outcrop, megascale)

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Igneous rocks a.ka. Magmatic rocks

Magmatic rocks• Intrusive rocks a.k.a. plutonic rocks (hard, crystallization of magma in

deep bedrock)• Volcanic (lava flows produced by eruptions of magma)• Intrusive dikes and sills• Also: Pyroclastic deposits and rocks (products of explosive eruptions of

magma that have deposited directly without sedimentation andreworking cycles)

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Igneous rocks

Page 22Kuva: GTK/Paavo Härmä

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Volcanic rocks

• Most magma erupting on the surface as lava flows is basaltic• Andesites comprise smaller lava flows• Dacites and rhyolite lavas much less common• Relation of pyroclastics is opposite! Why?

Explosive eruptions

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Dykes

- Represent intrusion channels for magma- Cooled faster than intrusive rock but slower than volcanic rocks

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Sedimentation processes

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Sedimentary cycle

Transport byWater, wind,mass-flows,glaciers

Deposition asclastic orchemicalsediments

Stratifiedbeddingx-beddinglaminationgraded bedding

Massive

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Sedimentary rocks

Sediments and clastic sedimentaryrocksRounding of grains• Transport distance and mechanisms• Multiple cycles possibleSorting of grains• Depositional mechanismCement• Transforms a sediment to sedimentary rock• Cement: e.g. granular, prismatic• Matrix: microcrystalline matter, mainly deformed and recrystallized

grains

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Sandstones

Silica gel comprising hydrous, amorphous SiO2 and acommon cement in sandstones leads to alkali reactionswithin (manmade) portland-cement-pastes inducing seriousdamage to concreteQuartzite and quartz sandstone comprising crystalline SiO2(quartz) is hard and durable material that commonlycomprises excellent aggregates (but can be difficult to drillor excavate)!

MudstonesShales are one of the common building stones• Mudstones (and their low-degree metamorphic equivalents) can be

extremely difficult in terms of geotechnical properties- Disintegration when exposed to air and rain

• spalling- Low plasticity and liquid limits- Erosion- Expandable clay minerals

• Expand when dry clay is wetted• Also in wet clay if composition of water changes and induces ion exchange (Na to Ca)

On the other hand: BGS was established in 1832 to map mudstonesand shales that could be excavated easily• Construction of channel system to Devon, UK

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Non-clastic sedimentary rocks

Carbonate rocksEvaporites (particularly challenging forconstruction)PhosphoritesThe GIS approach to evaporite-karst geohazardsin Great Britain A. H. Cooper, Environ Geol (2008)53:981–992 ,DOI 10.1007/s00254-007-0724-8

Metamorphosis

(Complete) recrystallization due to changes in temperature and pressure or temperatureRegional metamorphosis• Driven by tectonic processes (deformation)Contact metamorphosis• Driven by magmatismNew mineral assembly• No changes in overall chemistry• Adding or removal of fluids (water, carbon dioxide)

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Deformation and metamorphosisleads to anisotropismGneisses and migmatiteshowever, have higher strengthsthan schistsRetrograde metamorphosis andalteration along shear planes:particularly potential zones ofshear failure

Classification ofrocksexamples

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Igneous rocks

A “field method” formacroscopic observationA standard method based onmicroscopic studies

EN 12670:2001

Classification ofvolcanic rocks

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EN 12670:2001

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Pyroclastic rocks

Based on volcanic “clasts”Composition (SiO2)

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Mudstones

Shale: fissile tectureMudstone preferable used when massive

Marl= clay +fine carbonates

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Field classification of sandstones

Classification based on grain size(clast size)The following is based classificationby Dickingson (1978)• For macroscopic studies

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Carbonate rocks

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Limestone classification

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Metamorfic rocks

Simplified field classification

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(For the following not included terms:eclogite, granulite, leptite, migmatite,ophicalcite,phyllite,serpentinite, see 3.1.)

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Compton: Geology in the Field