Review Notes: Building Materials - Building Stones, Gypsum and Lime

BUILDING STONES, GYPSUM AND LIME

Building Stones – stones usually blocks or pieces of the basic material rock.

Classification:
1. Three general categories:
a. Igneous – formed as a result of the cooling of molten matter.
b. Sedimentary – formed by the action of water either by depositing materials at the bottom of a water body or depositing them on the earth’s surface.
c. Metamorphic – rocks changed from their original structure by the action of extreme pressure, heat, or various combinations of these factors.
2. Classified according to form:
a. Rubble – includes rough fieldstone which may merely have been broken into suitable sizes, or it may include irregular pieces of stone that have been roughly cut to size, usually used for and filling material. (escombro and lastillas)
b. Dimension (Cut stone) – consists of pieces that have been cut or finished according to a set or drawing. (for facing walls)
c. Flagstone (Flat slabs) - consists of thin pieces (1/2 in. and up which may or may not have had their face dimensions cut to some particular size. (for walks and floors)
d. Crushed rock – consisting of pieces varying I size from 3/8 to 6 in. and is used to a large extent in concreting.

Building Stones:

1. Argilite – one formed d\from clay, commonly dark-blue with faint shades of green, used for floor tile, stair treads, coping stones, interior wall base, interior window stools of exterior window sills.
2. Granite – igneous origin and composed of quartz, feldspar, hornblende and mica.  Its generally very hard, strong durable and capable of taking a high polish.
3. Limestone – a sedimentary rock which is either oolitic, or calcite cemented calcareous stone formed of shells fragments, particularly non-crystalline in nature, it has no cleavage lines and uniform in structure and composition.
4. Travertine – a sedimentary rock, composed mainly of calcium carbonate. It has been formed at the earth’s surface through the evaporation of water from hot springs.
5. Marble – metamorphic rock, one that has been changed from its original structure in this case, limestone and dolomite have been recrystallized to form marble.
6. Serpentine – igneous rock with the mineral serpentine. The mineral is olive green to greenish black, but impurities may give the rock other colors.
7. Sandstone – a class of rock composed of cemented silica grains. Colors include gray, buff, light brown and red.
8. Slate rock – formed by metamorphosis of clays and shales deposited in layers. A unique characteristic of the rock is the relative ease with which it may be separated into thin tough sheets, called slates, ¼” or more thick.

Stone Construction:

1. Paneling – consists of using slabs of stone cut to dimension and thickness to cover backup walls and provide a finished exterior.
2. Ashlar – work requires the use of cut stone and includes broken ashlar, irregular coursed ashlar, regular coursed ashlar.
3. Rubblework – used as random when no attempt is made to produce either horizontal or vertical course lines. Small spaces are filled with spalls, small stones and used as course rubble work, horizontal course lines are maintained but no vertical course lines used.
4. Trim – involves use of stones cut for a specific purpose and include Quoin – stones laid at the intersection of two walls.
a. As jambs – stones which form the sides of window and door openings.
b. As sills – stones which form the bottom of window and door openings
c. As belts – special stone courses which are built into a wall for a particular purpose. One reason is to provide architectural relief to a large wall of one material or to provide a break I the vertical plane of the wall, another reason is to hide a change in the wall thickness.
d. As copings – one which is cut fit on the top of a masonry wall. It prevents the passage of water into the wall, sheds water to either inside or outside, and gives a finished appearance to the wall.
e. As cornices – specially cut stones which are built into and project from a masonry wall near the top to provide the appearance of a cave.
f. As lintels – stones which bridge the top of door and window openings.
g. As stone steps – made to fit over an inclined concrete slab or to cap steps cast in concrete.
h. As an arch stone – cut to form some particular type of arch over a door or window opening.
i. As stone flooring – walks and patios, made by covering a base of stone concrete, brick or tile with flagstones, trimmed flagstone, trimmed rectangular and square.

Gypsum – a soft mineral consisting of a hydrated calcium sulfate from which gypsum plaster is made (by heating); colorless when pure used as a retarder in Portland cement.

Posted in: BldgMatls