Sand reinforced polyester composites (SPCs), are

building material Building material is material used for construction. Many naturally occurring substances, such as clay, rocks, sand, wood, and even twigs and leaves, have been used to construct buildings and other structures, like bridges. Apart from natur ...

s with

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

acting as reinforcement in the

composite Composite or compositing may refer to: Materials * Composite material, a material that is made from several different substances ** Metal matrix composite, composed of metal and other parts ** Cermet, a composite of ceramic and metallic material ...

. Pioneers in using sand reinforced composites include

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

business men Gerhard Dust and Gunther Plötner, who made sand reinforced composite

bricks A brick is a type of construction material used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a unit primarily composed of clay. But is now also used informally to denote building u ...

with

polyester resin Polyester resins are synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Maleic anhydride is a commonly used raw material with diacid functionality in unsaturated polyester resins. Unsaturated polyester r ...

and hardener to provide emergency relief housing for those affected by the 2010 earthquake in

Haiti Haiti, officially the Republic of Haiti, is a country on the island of Hispaniola in the Caribbean Sea, east of Cuba and Jamaica, and south of the Bahamas. It occupies the western three-eighths of the island, which it shares with the Dominican ...

. Sand was used in the composites because of its abundance and ease in obtaining.

Composition

The composition of sand is highly variable depending on the origin of the sand. The most common material found in non-tropical, coastal, and inland sand is

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

usually in the form of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

– which is considerably hard and one of the most common minerals resistant to weathering.

Preparation

* Drying sand * Mixing with alternate material(s) * Adding a hardener to the mixture (such as methyl ethyl ketone peroxide) * Pouring mixture into mold and drying * Releasing from mold and smoothing

Properties

* SPCs decrease water absorption because of the

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

nature of sand. * The

compression strength In mechanics, compressive strength (or compression strength) is the capacity of a material or structure to withstand loads tending to reduce size (compression). It is opposed to ''tensile strength'' which withstands loads tending to elongate, r ...

of SPCs is typically lower than non-sand reinforced composites. *

Flexural strength Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the Stress (mechanics), stress in a material just before it Yield (engineering), yields in a flexure test. T ...

of SPCs decreases with an increasing

weight percent In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition. Some sta ...

of sand. The composite becomes increasingly

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. ...

as the weight percent of sand increases. * A greater weight percent of sand increases the composite's

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by Pressing (metalworking), pressing or abrasion ...

(

Vickers hardness test The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell scale, Brinell method to measure the hardness of materials. The Vickers test is often easier to use than ot ...

) – sand has reinforcing capabilities. *

Thermal conductivity The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low ...

decreases with a greater weight percent of sand. Sand has insulating properties.

References

{{Reflist Composite materials