|
|
Present: Mark Almeda, Bill Barry, Nicole Benjamin-Ma, Chris Dabek, Marilyn Fenollosa, Matt Formicolia, Jack Glassman, David Kelman, David King, Ryan Maciej, Arthur MacLeod, Doug Manley, Melissa McGrew, Deborah Robinson, Deane Rykerson, Susan Schur, Malcolm Smiley, Jonathan Smith, Richard Tobin, and Sara Wermiel 1. Concrete and Cast Stone Conference: Susan Schur put together another fine conference this year. Jack Glassman commented that it was packed with information, and he appreciated that it covered the future of concrete and cast stone as well as the past. Bill Barry seconded that; in combining the present and past, buildings - whether old and new - simply became examples of architecture, and thus preservation was treated as part of mainstream practice, which he believes it is. He liked the international perspective as well, for example, the discussion about contemporary architecture in Brazil. 2. Traditional Buildings meeting: Many HRC members attended, but reaction was muted. Deane Rykerson wished that the plastic and vinyl exhibitors could be banned. 3. Philips Academy, Andover, Fuller Memorial Bell Tower brick growth: Arthur MacLeod, P.E., of MacLeod Consulting, Inc., discussed the little known problem of brick growth due to freezing. Cracks in the walls, at the four corners, of the 1923 Fuller Bell Tower, about which he had been asked to make a report, had been puzzling. The tower had a steel skeleton with brick infill, and it had a second steel frame inside to support a wooden spire. In his 2004 report, Arthur concluded the tower had to be rebuilt. But what caused the cracks? There were no salt or rust stains, which seemed to rule out rustjacking or ice. In the 1970s, the school's maintenance records began to mention cracks. Why had the cracks developed only after 50 years? Then during demolition, Arthur saw that a column flange was bent out of plumb about ¼ inch, but had little rust. He concluded that growth of the inner lining of bricks, between the columns, had pushed the column and caused the cracks. And since this had occurred long after the building was completed, the growth in the bricks was probably not due to moisture but to freezing. Brick expands and contracts with temperature changes, but it can grow irreversibly from moisture and from freezing. At the time the tower was built, brick growth wasn't recognized as a phenomenon. Moisture growth, where bricks absorb moisture from the atmosphere, occurs in the early life of bricks, reaching a maximum at about 15 years. Freeze growth, resulting when saturated brick freezes, can happen at any time. Freeze growth in bricks is about half the amount as from moisture. Little has been published on freeze growth; Arthur was able to find few references to it, and it is not well understood. The tower had hard-burned face brick on the outside and softer brick inside, with few headers as bonds between the skins. It seemed the expansion problem was confined to the softer backup brick inside this unheated tower. Arthur noted that he's seen abandoned (i.e., unheated) buildings without cracks, while others have cracks. He concludes that brick growth seems to be related to brick quality. Brick growth is less likely to occur in a heated building, although parapets may have this problem. Arthur felt brick companies were unlikely to support research into this, since it's a problem for old bricks. Susan Schur suggested Arthur send this case to the National Brick Research Center at Clemson University; perhaps they would look into it. The solution in the Fuller tower was to put in zipper joints at the four corners, sealed with caulk. Bill Barry asked what would have happened if the bonding had been better. Arthur thinks the cracking might have been more random. Doug Manley asked if the hardness of the mortar was factor. Arthur replied that the mortar contained little lime, but the real problem in his judgment was the differential growth of the softer inner skin and hard outer skin. 4.Tours: Several members suggested tours for the HRC: the Chestnut Hill Waterworks, Boott Mill canal, and repeat of the Strawbery Banke tour. We'll keep you posted. In any event, the next tour will be Saturday, May 17, 2008, of the Hancock-Clarke House, Lexington, MA, which is undergoing rehabilitation. Deane Rykerson will be our guide, and he will introduce the project at the May HRC meeting. 8: 00 a.m., Thursday, 8 May 2008 Featuring Deane Rykerson, Rehabilitation of the 1737-38 Hancock-Clarke House, Lexington, MA The Architects' Building, 52 Broad Street, Boston Henry Moss, Matthew Bronski, and Sara Wermiel co-leaders and scribes
|