<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">concrete blocks</topic></authority><related type="other"><topic>concrete</topic></related><related type="broader"><topic>masonry units</topic></related><related type="broader"><topic>construction block</topic></related><variant type="other"><topic>block, concrete</topic></variant><variant type="other"><topic>concrete block</topic></variant> <note xml:lang="en"><![CDATA[ Large units of building material made from a mixture of cement and an aggregate, usually 8 x 16 inches and of various thicknesses.  A mixture of cement, aggregate, and water is vibrated and compacted in steel molds and then cured in air, steam, or under autoclaving processes. Became a very popular building material beginning in the early 20th century. ]]></note></mads>