This blog reports events and interesting tidbits from Rensselaer, Indiana and the surrounding area.

Wednesday, February 20, 2013

Lime and Portland cement mortars

Winter is visiting this week. I could not resist taking a picture of the stop sign below that had been coated with snow, which had then slipped a bit.
 Speaking of visiting, I visited the Jasper County Historical Society Museum last night (Tuesday) to attend their monthly business meeting. One of the announcements was that the historical society would be adding to its collection of buildings on the Fair Grounds. It will be a small addition, and it will be nonfunctional, but it will represent something that was an essential part of life in the early days of the county and because of its importance--pity the home without one--it deserves to be represented. Yup, there will be an outhouse added to the collection. As I said, it will be non-functional and locked to prevent anyone from trying to use it. Of course, most young people probably would not know how to use it. I remember that almost fifty years ago, when I was working a summer job at a camp that catered to rich kids from the northern suburbs of Chicago, that even then some of the kids were amazed when they saw a real outhouse. Far more kids today must be unaware of how bathroom needs used to be met.

The speaker for the evening was Dave Zeltwanger from Francesville who runs a business called DK & Sons, LLC. He does a lot of masonry construction and restoration and one of the projects he either has done or will do work for the Embers event hall. His basic message was that it is dangerous and foolhardy to combine old and new masonry techniques. Bricks made in the 19th century were fired at lower temperature than those today and absorb more water. (The only company that still makes bricks the old way is in Indiana, the Colonial Brick Company.) They were held together with lime mortar, a technology that goes back several thousand years. In the late 19th century Portland cement was invented and it works well with modern bricks, which are fired at a higher temperature and are less porous than the older bricks.

Mr Zeltwanger talked at some length about a renovation project gone bad at the Catholic church in North Judson. Twenty or thirty years ago a contractor repaired and renewed the exterior of the church by sandblasting the brick and replacing crumbling lime mortar with Portland cement mortar. The results looked great for about twenty years, but then the parishioners began to notice problems. Bricks were breaking. The problem was that the bricks absorbed water that was trapped because the new mortar was less permeable than the old, and the freeze-thaw cycles were cracking the bricks. There is really no easy remedy except to watch for problems and repair them as they occur.
Since repairs of this kind were not common until fairly recently and because inappropriate repairs can take decades to reveal themselves, the problems that mixing old and new masonry were not generally known back when the repairs in North Judson were done.

Did you know that Indiana limestone is the highest quality limestone in the U.S.? Weathering will remove about 1/16 of an inch per century. (There are buildings in St. Paul built from local limestone and they have weathered a lot more than 1/16 of an inch in a century. But in Minnesota the stone of choice is granite, such as Morton Gneiss, used in this building that was kitty-corner from my father's drug store in the 1950s.)

In other news from the meeting, the society is still looking for recipes and recipe-related stories of ancestors for a cook book that they want to publish this fall. They are also planning a Spring Tea.

1 comment:

Anonymous said...

You are a good chronicler. The presentation was quite good and informative.