Portland cement
June 3, 2009 by blogtopia
Filed under Definitions
Portland cement is the most common type of cement in general use around the world, because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate which controls the set time, and up to 5% minor constituents (as allowed by various standards).
As defined by the European Standard EN197.1, "Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 and 2CaO.SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass." (The last two requirements were already set out in the German Standard, issued in 1909).
Mortar
June 3, 2009 by blogtopia
Filed under Definitions
Mortar is a workable paste formed by mixture of cement, water and fine aggregate sand to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar is a mixture of sand, a binder such as cement or lime, and water and is applied as a paste which then sets hard. Mortar can also be used to fix, or point masonry when the original mortar has washed away.
The first mortars were made of mud and clay. Because of a lack of stone and an abundance of clay, the Babylonian constructions were of baked brick, using slime or pitch for mortar. According to Roman Ghirshman, the first evidence of humans using a form of mortar was at the ziggurat of Sialk in Iran, built of sun-dried bricks in 2900 BC. The Chogha Zanbil Temple in Iran was built in about 1250 BC with kiln-fired bricks and a strong mortar of bitumen.
Papercrete
June 1, 2009 by blogtopia
Filed under Definitions
Papercrete is a recently developed construction material which consists of re-pulped paper fiber with Portland cement or clay and/or other soil added. First patented in 1928, it has been revived since the 1980s. Although perceived as an environmentally friendly material due to the significant recycled content, this is offset by the presence of cement.
The material lacks standardisation, and proper use therefore requires care and experience. Eric Patterson and Mike McCain, who have been ascribed with independently "inventing" papercrete (they called it "padobe" and "fibrous cement"), have both contributed considerably to research into machinery to make it and ways of using it for building.