Engineering brick

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Engineering bricks are a type of brick used where strength, low water porosity or acid (flue gas) resistance are needed. Engineering bricks can be used for damp-proof courses.^[1]

Clay engineering bricks are defined in § 6.4.51 of British Standard BS ISO 6707-1;2014 (buildings & civil engineering works - vocabulary - general terms) as "fire-clay brick that has a dense and strong semi-vitreous body and which conforms to defined limits for water absorption and compressive strength".^[2]

Stronger and less porous engineering bricks (UK Class A) are usually blue due to the higher firing temperature^[3] whilst class B bricks are usually red. Class A bricks have a strength of 125 N/mm² (18,100 lb_f/sq in) and water absorption of less than 4.5%; Class B bricks have a strength greater than 75 N/mm² (10,900 lb_f/sq in) and water absorption of less than 7%.^{[citation needed]}

Accrington brick is a type of engineering brick that was used in the construction of the foundations in the Empire State Building in New York City.^{[citation needed]}