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Mortar (masonry)
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<p>Mortar is a workable <a href="/facts/Adhesive/shTfIJ0E">paste</a> which hardens to bind building blocks such as <a href="/facts/Rock_(geology)/FXCJkmop">stones</a>, <a href="/facts/Brick/2CBPgDIK">bricks</a>, and <a href="/facts/Concrete_masonry_unit/kpnN48EV">concrete masonry units</a>, to fill and seal the irregular gaps between them, spread the weight of them evenly, and sometimes to add decorative colours or patterns to <a href="/facts/Masonry/TlaDzpUp">masonry</a> walls. In its broadest sense, mortar includes <a href="/facts/Pitch_(resin)/GpdKnQMa">pitch</a>, <a href="/facts/Bitumen/tW6EqphW">asphalt</a>, and soft clay, as those used between bricks, as well as cement mortar. The word "mortar" comes from the <a href="/facts/Old_French/QcRpPdAc">Old French</a> word <i>mortier</i>, "builder's mortar, plaster; bowl for mixing." (13c.). </p><p><a href="/facts/Cement/VfDMkk12">Cement</a> mortar becomes hard when it cures, resulting in a rigid <a href="/facts/Aggregate_(composite)/dKfhlNIw">aggregate</a> structure; however, the mortar functions as a weaker component than the building blocks and serves as the sacrificial element in the masonry, because mortar is easier and less expensive to repair than the building blocks. <a href="/facts/Bricklayer/38fsc60X">Bricklayers</a> typically make mortars using a mixture of <a href="/facts/Sand/MdTIt0M8">sand</a>, a <a href="/facts/Binder_(material)/GBxjQF0U">binder</a>, and water. The most common binder since the early 20th century is <a href="/facts/Portland_cement/kPj8EjnP">Portland cement</a>, but the ancient binder <a href="/facts/Lime_(material)/uMcVXGBM">lime</a> (producing <a href="/facts/Lime_mortar/LpSgBtvn">lime mortar</a>) is still used in some specialty new construction. Lime, lime mortar, and gypsum in the form of <a href="/facts/Plaster_of_Paris/GG73HRD7">plaster of Paris</a> are used particularly in the repair and <a href="/facts/Repointing/yxSWGCX9">repointing</a> of historic buildings and structures, so that the repair materials will be similar in performance and appearance to the original materials. Several types of cement mortars and additives exist. </p>