Building Technology (Natural Stone)

Stone

Stone

piece of rock that is used for a specified function (building stone, gravestone, gemstone, cobblestone streets)

Principal building stones

• Limestones, marbles, granites, and sandstones. 

• serpentine and quartzite are used locally but to a much lesser extent

• Stone makes an excellent building material if properly but the cost may be high

Properties of Stone

• depend on what nature has provided.

• designer does not have the choice of properties and color

Rock

natural material composed of an aggregate of one or more minerals, volcanic glass, or organic materials (coal, shells)

Sedimentary Rocks

• materials weathered from pre-existing rock

• commonly have a layered appearance due to grains of different composition, color, or size depositing at different times

Bedding

 layering of sedimentary rocks

Igneous Rocks

the solidification of molten rock.

Intrusive Igneous Rocks

• crystals that are large enough to be seen with the naked eye 

• rocks cooled slowly, deep within the Earth thereby allowing time for the crystals to grow

Extrusive (volcanic) Igneous Rocks

• cool very quickly after they erupt from a volcano, and 

• composed of microscopic crystals. 

• poor building stone because they may be weak, cracked, inconsistent in color, and/or contain large pores

Metamorphic Rocks

preexisting rocks are exposed to elevated heat and pressure

Foliation

• the layering after directed pressure reorients elongate or flat minerals to be parallel to each other

• Rocks that have been substantially changed from their original form

Gneiss

distinctly banded rock subjected under more extreme metamorphic conditions, minerals segregate into distinct light and dark colored layers

Crystals

• individual minerals that have grown in place to form a rock. tend to have regular, polygonal shapes

C1: Crystals

cleavage fragments of minerals such as calcite, halite, and feldspar

Grains

• pieces of pre-existing rock or organic material (e.g., shells) that have been cemented together

• rock must be sedimentary

Bedding

layering exhibited by sedimentary rocks defined by changes in the color or size of grains LAYERING OF SEDIMENTARY ROCKS

Sandstone

composed of small (<2mm diameter) rounded grains

Conglomerate

composed of rounded pebbles

Shatter/breaks

If a rock ———- then the grains of rock will tend to be irregular, jagged, and angular.

breccia

Once cemented, angular clasts (rock fragments) form a rock called

fossil grains

(from animal shells/skeletons) have complex and delicate shapes such as spirals, discs, arcs

G1: Rounded Grains (Pebbles)

fragments of mechanically weathered rock that have had their rough edges smoother by abrasion during transport in water (river or beach environment)

G2: Angular Grains

fragments of mechanically weathered rock that have not been abraded

G5: Ooids

a special form or spherical rounded grain of calcite that forms by accreting like a snowball as they roll around on the shallow seafloor due to wave energy)

Foliation

layering produced when minerals such as micas and amphiboles are aligned parallel to each other LAYERING OF METAMORPHIC ROCKS

Gneiss

• extreme metamorphism characterized by the segregation of minerals into distinct layers, typically bands of: 

• light minerals (quartz & feldspars) 

• dark minerals (biotite & amphibole) LAYERING OF METAMORPHIC ROCKS

Folding

Deformation of the rock results in the —— of metamorphic rocks.

40 and 100mm

outer stone wall is only a cladding consisting of thin sheets of stone，normally between ——— in thickness fixed to the concrete shell of the building with corrosion resistant metal fittings.

outer part of the cavity wall

where stone is used for the ————the load is only the wall itself.

CRYSTALLIZATION TEST

• for limestones and some sandstones

• Based on 19th century tests for frost susceptibility

• determination of the loss of weight of a sample after 15 cycles of alternately being soaked in a solution of sodium sulphate then dried in a humid oven.

• test samples are compared to known internal standards.

SATURATION COEFFICIENT AND POROSITY

originally a test for frost susceptibility

saturation coefficient

ratio of the volume of water which can be absorbed to the total volume of pore space

High saturation coefficients

poor durability

RUBBLE

• rough fragments of broken stone that have at least one good face for exposure

• broken pieces (brick, stone, concrete) from demolition work and building waste is used as fill and hardcore

DIMENSION STONE

• Natural stone block, cut stone

• piece of natural stone cut into rectangular blocks for use in ashlar masonry.

• quarried and squared stone 2” or more in length and width and of specified thickness, 

• wall panels, cornices, copings, lintels and flooring.

FLAGSTONE

• flat stone slab 

• paving, flooring and horizontal surfacing

Crushed stone

used as aggregate in concrete products.

Pebbles

larger than granules (2-4mm diameter) and smaller than cobbles (64-256 mm diameter)

ARGILLITE

• formed from clay

• dark blue with faint shades of green.

GRANITE

• light-colored igneous rock with grains large enough to be visible with the unaided eye.

• hard, strong, durable and capable of taking high pressure polish. 

• composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals

• from the slow crystallization of magma below Earth's surface.

• Red, pink, yellow, green, blue, white and brown

LIMESTONE

• sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite.

• forms in clear, warm, shallow marine waters.

• organic sedimentary rock that forms from the accumulation of shell, coral, algal, and fecal debris

TRAVERTINE

sedimentary rock formed by precipitation of carbonate minerals from solution in ground and surface waters or geothermically heated hotsprings

MARBLE

• Metamorphic rock, a re crystallized limestone 

Forms into carrara, parian, onyx and Vermont

SERPENTINE

• Igneous with mineral serpentine. 

• olive green to greenish black but impurities may color the rock.

Used only for interiors due to weathering

SANDSTONE

• Class of rock of cemented silica grains with texture ranging from very fine to very coarse. 

• Colors vary from buff, red and light brown

SLATE ROCK

• fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by lowgrade regional metamorphism. 

wide variety of uses such as roofing, flooring, and flagging because of its durability and attractive appearance

PANELING

• Thin slabs of stone cut to dimension and thickness 

• cover back up walls and provide finished exterior and interior walls STONE CONSTRUCTION

Uncoursed Masonry

1. cobblestone wall, cobble wall, uncoursed field stone, rough rubble wall, common rubble wall

2. polygonal wall, cyclopean masonry, Pelasgic masonry

3. ragwork, slate walling

4. wall of stone slabs

5. random rubble wall, uncoursed rubble wall

6. uncoursed squared rubble wall

7. uncoursed ashlar wall

Coursed Masonry

1. irregular coursed rubble wall 

2. coursed squared rubble wall 

3. coursed ashlar wall 

4. regular coursed rubble wall

5. regular ashlar wall

ASHLAR MASONRY

Masonry blocks or facing stone which has been dimensioned, squarely dressed and laid in bonded courses with narrow joints

Coursed ashlar

• laid out in courses of equal height

• Blocks of various sizes may be combined to make up height of the course

Random Ashlar

laid without regular course but with an overall effect of horizontal orientation

RUBBLEWORK

• random and no attempt to produce orderly course either horizontally or vertically

• Small spaces filled with smaller stones

Coursed rubble

fieldstone or roughly dressed stone, with or without mortar, assembled to give a effect of courses

Uncoursed Rubble

• stones are not arranged in a course

• the stones are not placed in a horizontal layer rather just stacked over one another

Fieldstone

• stone found on the ground (not quarried) that is a suitable size and shape for use as drywall or rubble masonry

TRIM

stone cut for specific purposes

Surface finishing

• influences stone selection. 

• provide different characteristics such as slip resistance, chemical resistance, and maintenance STONE FINISHES

POLISHED

• shiny glossy surface achieved by using diamond abrasives grit followed by polishing powder

• very smooth and has a mirror-like effect

• not porous and has higher resistance to humidity and chemicals. 

Typically used for internal floorings STONE FINISHES

SANDBLASTED

• A matte textured surface with no gloss as a result of a pressurised flow of sand and water. 

Typically used for exterior walls STONE FINISHES

HONED

• Uses diamond abrasives as well.

• surface is smooth, non-reflective and is more porous, unlike a polished finish. 

Typically used at both internal and external areas with less exposure to chemical or moisture STONE FINISHES

ABRASIVE

• flat, non-reflective surface with no gloss. 

Typically used for areas exposed to weather such as entries, foyers STONE FINISHES

EXFOLIATED (FLAMED)

• rough and very porous surface that is produced by applying a high temperature flame to the surface of the stone causing crystals to pop. 

Typically used for external areas where slip resistance is prioritised STONE FINISHES

NATURAL OR CLEFT

absence of treatment to leave the stone in a natural condition STONE FINISHES

Stonework

• any part of a building, structure, cladding or paving, which incorporates natural stone as a primary material;

• construction and detailing in stone STONE FINISHES AND RUSTICATION

Natural Stone

• stone which has been quarried, cut, shaped and dressed for use in the construction industry STONE FINISHES AND RUSTICATION

Rustication

• decorative rebates or sinkings around edges of individual stones to emphasize joints and give articulation to surface

• especially prevalent in Renaissance architecture STONE FINISHES AND RUSTICATION

Stonework Finish

various factory or tooled treatments applied to the stone surfaces of a building, or natural stone slabs STONE FINISHES AND RUSTICATION