Wachuwannano

BY MICHAEL A. GARDNER,

A.K.A. MR. WACHUWANNANO

Our February column asked you, kind Clinker is the “bluish-gray substance Believing that the positive building reader, to tell us the meaning of the created when an intimate mixture of characteristics of the stone could be word “portland” as it is used in the term calcareous and argillaceous minerals” replicated in a lesser cost material, he portland -based plaster. are “strongly heated.” Aspdin mixed his began to experiment with various com- materials together, ground them up binations of ingredients. He ultimately First across the finish line with an accu- and heated the ground-up mixture. settled on a hydraulic cement mix— rate answer was Washington, D.C., When the heated mixture was burned, mostly clay and limestone—that was specification consultant extraordinare, he had clinker. He ground up the clink- water-resistant, set very hard and was David Metzger. He narrowly beat out er, called it , added similar in appearance to the stone he Charles Gerstle, a Louisville, Ky., stone water and an aggregate, probably sand, sought to imitate. He called his new consultant. and created portland cement-based mix “Portland cement,” and named it plaster. The process of creating clinker in honor of , the popular David wrote: is still used in modern portland cement name for the stone that he sought to manufacturing, although on a much copy. As far as we can tell, most of that Just got my February issue of Con- larger scale than in Aspdin’s era. stone was quarried on the Isle of Port- struction Dimensions, and, as usual, land in the English Channel. One of turned right to Wachuwannano. (Quotes in the above paragraph are the reasons that it was so expensive was from Brady and Clauser: Materials the cost of transporting it from island According to Caleb Hornbostel’s “Ma- Handbook. Other references used in quarries to other parts of . terials in Architecture” (which has been the creation of this column include a wonderful reference book for me; I’ve Diehl: Manual of Lathing and Plaster- Portland cement experienced its first re- had my copy since 1971), portland ing and Bucholtz: The Consumer’s corded use as a building material in the cement was invented in 1824 by an Stucco Handbook.) United States in 1868. Joseph Aspdin’s English mason named Joseph Aspdin. new material was so low in cost that it He combined lime, silica, iron oxide To elaborate further, Aspdin was, as was initially shipped to the new world and alumina in specific proportions, David stated, a mason who lived and in the bottom of cargo ships, where it pulverized the mixture, burned it to a worked in the area around , Eng- was commonly used as ballast. clinker and then ground the clinker land. Aspdin was enamored of the pos- into a finished product that he called itive Characteristics—durability and an About the Author portland cement, after the Isle of Port- ability to resist water penetration—of Michael A. Gardner is AWCI’s director land in the English Channel. the most popular building stone used of technical services. Send your techni- in England during the early 13th cen- cal questions to Construction Dimen- Now, what’s a clinker? tury. He was not, however, pleased by sions, or send your e-mail via the Inter- the high cost of the stone material. net at [email protected].

Official Publication of AWCI 37