The dimensions range from 4”x4”x8” to 8”x12”x16”, with angle blocks reaching up to 21” long. They are divided into pier, stretcher, sash, hollow return corner, and 45° angle. Today, there are at least 32 different shapes and dimensions of cinder block. When purchasing lighter cinder blocks today, the seller should be able to tell you if they contain ash or pumice. The term ‘cinder block’ has come to mean light-weight low-density blocks, and more confusingly, to be synonymous with any hollow core concrete block. The hollow-core blocks are still used in some foundations and other construction applications, landscaping, gardening, fire pit and place construction, benches, and hundreds of other locations and uses.Īlthough ash is less commonly used as an aggregate replacement today in blocks, it is used as a mixing agent in most blocks, and to lighten Group 2 concrete blocks. They are often used in alternating patterns with concrete blocks to reduce weight without weakening the construction. Today, the lighter cinder blocks are used in walls in large construction projects where their weight is a bonus, and they don’t have to carry any load. The toxins are linked to nervous disorders, cancer, health complaints, and decreased cognitive ability. The blocks are prone to moisture damage, buckling, bowing, and lack the tensile and shear strength of concrete blocks.Īnother drawback to cinder blocks was the toxic nature of the coal ash used in their manufacture. Cinder blocks are still used today but are prohibited in some building applications under building codes. Today, 12 million tons of coal ash or cinder is used as a strengthening agent to make light-weight concrete blocks. Cinder blocks had many uses in the construction industry until about 50 years ago when poured concrete wall construction became more common. The fireproof blocks were used in all facets of construction, from foundation to interior walls. The hollow cores make it easy to reinforce the cinder block construction by filling the cores with concrete. Masons found the lighter weight easier to lift and maneuver on scaffolds, or for lifting and threading over rebar. The blocks are light-weight, provide some insulating value, and nails can be hammered into them. After several years of experimenting, he arrived at the best mixture ratio, and the cinder block was born. The process of using coal ash was invented in 1913 by Francis Straub, a brick mason in Pittsburgh, who had experimented with waste ash from the coal and steel plants as an aggregate to produce a lighter brick. The fine ash is also known as breeze in the United Kingdom, which is why they are called breeze blocks in the UK. The cinders are the fly or bottom ash left from burning coal for different purposes. Portland cement, invented in 1824 in England, is made by heating limestone and mineral clay to form clinker, which is then ground into a powder and mixed with 2% to 3% gypsum. Cinder blocks commonly have two or three hollow cores in the middle. The mixture is poured or pressed into molds and either heated to dry, or air-dried. They are manufactured from a mixture of Portland cement and an aggregate of cinders from burned coal hence, their name. What Is a Cinder BlockĬinder blocks are light-weight low-density construction blocks, or concrete masonry units (CMU). A highly automated cement block plant today can easily manufacture several 1000 blocks an hour, ensuring concrete blocks are readily available for multiple projects. Hand casting 1,200 to 4,000 blocks for a foundation, however, would have been labor-intensive, grueling back-breaking work for two people over several weeks. These blocks were lighter and less expensive to produce and are the foundation of the modern concrete block. Palmer of Tennessee, and in 1899 he patented the hollow concrete block machine. Although not as durable as the lost Roman formula, it was more portable and less expensive than quarried stone blocks.įrom the 1830s onward, different patents were issued for concrete block making machines – some of which produced blocks weighing 180 pounds! In 1889, a mold for solid concrete blocks was issued to Harmond S. The redevelopment of concrete began in 1756, but the modern formula wasn’t patented until 1824. The art of making concrete, invented by the Romans around 300BCE, was lost when their empire fell.
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