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Week 13 – Holiday Lights, Music, and Surprises (in the durability of internal and external bearing walls)

December 7, 2009

Holiday lights across Via della Scala in the Trastevere section of Rome

The holiday season is now upon us, and lights are strung across many streets in Rome. A few of the holiday lights started to appear in the last week of November, but the majority appeared this past week – the first week of December. After years of American retailers erecting their holiday decorations earlier and earlier, I find it refreshing that most of the holiday lights and decorations here appear around December 1st, not sometime in October.   The panettone and other traditional Christmas breads and treats are prominently displayed in many shops. I went for a Sunday stroll last evening in Trastevere (an old medieval neighborhood at the bottom of the hill from the American Academy) and took these photos.   For a Sunday evening, many more people were on the streets than usual, not frantically shopping, but just out with family for a passeggiata (evening stroll), enjoying the lights and the ambiance and joy of the season.

Holiday lights at the intersection Via di Ponte Sisto and Via Benedeta in Trastevere

The band Superfetazione played at an Academy happy hour held in one of our apartments...

Last weekend, a regular happy hour event at the Academy had an additional measure of good cheer, as we celebrated the birthday of T. Corey Brennan, the Mellon Professor-in-Charge of Classical Studies here at the American Academy in Rome. Corey is an incredibly talented and accomplished guy, with broadly diverse talents. In addition to being an esteemed scholar of Ancient Greece and Rome, with degrees from Penn, Oxford and Harvard, he’s an accomplished rock musician who was a guitarist and songwriter in some notable late 80’s and early 90’s Boston-based rock bands, including The Lemonheads and Bullet LaVolta the Academy crowd swayed and danced to the music.

 The Italian band Superfetazione played at this happy hour, with help from a few members of the band Audiozoo. I later learned that Corey founded Superfetazione back in the 1980’s when he was a Fellow here at the Academy, so the band has been going for decades. One of the highlights of the evening was Corey’s 5 year-old son Nicholas belting out background rhythm vocals on some of the songs.

The artist Roma Pas (L) and me (R) at the AAR's masque dance party. The eyes of Roma's masque are cucumber slices. My mask was a Cornflakes box only a few hours earlier.

This past Saturday night the American Academy hosted a masque dance party for all the other foreign academies in Rome (there are quite a few).  The organizers translated the invitations into 14 different languages.  Corey was the DJ spinning the dance tunes, and we had festive lights of a different sort projected on the walls of the artist’s studio that served as the dance floor. The party was a lot of fun, as was seeing all the different masques. We inadvertently discovered that we Americans like to dance a whole lot more than some of our brethren scholars from the European academies. Oh well.

Museo di Roma, in Palazzo Braschi

While the weekends include these social events, the weekdays are for work on our projects. I’ve made quite a few site visits the past few weeks, to 6 different sites. In addition to making observations at other study sites, I’ve been observing the structural stabilization and renovation work at the Museo di Roma in Palazzo Braschi over the last couple weeks. The Palazzo is one of the younger buildings that I’ve been studying in Rome – it “only” dates to 1790. It was designed by Cosimo Morelli in the neo-Renaissance style, and it’s a convincing execution – walking by it, you’d think the building is from the 15th or early 16th century. The Architetto supervising the work, Antonietta Russo, has been extremely helpful and gracious in giving me tours of the work.

In the cortile of the Palazzo Braschi

Although I’ve investigated problems with the bearing walls of buildings of this same time period in the United States, one thing really surprised me in this case that I’d never seen before.

The exterior walls (those with an exposure to the exterior, and hence to the weather, rain, acid rain, etc.) are in good condition and require no structural repair, while the interior walls (no exterior exposure, hence no exposure to the elements) are deteriorating, and require structural stabilization. Often the exact opposite is the case – since the exterior walls are subjected to a more severe environment, they are more deteriorated and require a greater level of structural repair than the interior walls.

Both the interior and exterior walls range from about 2-1/2 ft. to 4-1/2 ft. thick. The fundamental difference is the way in which they were constructed.

Exterior wall of Palazzo Braschi

Given their significant exposure to the weather and the elements, the exterior walls are constructed very robustly and durably. The outer foot or so is either travertine (stone) blocks, or a hard brick, while the remaining thickness of the wall is constructed of brick laid in regular courses. The entire thickness of the wall is built with a very hard, very strong mortar with a high percent of pozzolana (volcanic ash) in the lime (which improve the strength and durability of the mortar). I can’t pick away at the mortar with my fingers or a small hand tool – it’s very hard.

Interior walls, with friable (crumbling) mortar

On the other hand, the interior walls are constructed using a “scapoli de tufo” technique, as follows. The inner and outer 10 inches or so of the wall are constructed with brick, laid in regular courses. The entire inner core of the wall (a foot or more thick) is a random jumble of bricks and chunks of tufo stone, mixed with mortar and dumped into the wall. The entire interior wall is built with a very weak lime mortar, with little or no pozzolana. Consequently, the lime mortar is very weak and friable (“crumbly”)  – I can literally pick it apart with my fingers. Therein lies the problem. The brick and the tufo stone in the walls are still in good condition, but the weak mortar is crumbling. The mortar is simply too weak, even for an interior environment. This same general method of wall construction consisting of regular, coursed, inner and outer wythes of brick, with a masonry rubble and mortar core, probably would have worked fine if they had used a stronger, more durable mortar. (I say this because I’ve observed quite a lot of basically similar construction from ancient Rome, but with much stronger mortar, holding up well in far more severe exterior environments, with roughly 2,00o years in service, instead of the roughly 220 years in service of the Palazzo Braschi).

Structural consolidation of interior walls in process. Injection ports for micro-grout in-place.

As a result of this deterioration of the interior walls, much of the structural stabilization work involves injecting a micro-grout into cracked areas of the walls, to structurally consolidate the most deteriorated areas of these walls. Some of this work is on bare brick walls, or non-descript plain plaster, but unfortunately, some of it must go through murals and other ornamentally painted plaster. But this work is truly necessary to structurally stabilize the underlying structure of these murals, before even worse damage occurs. It makes one wish the original builders in the 1790’s had just used a stronger mortar originally, as they did on the exterior walls.

Structural stabilization of the masonry wall beneath this mural was completed by drilling injection ports along cracks ,and injecting micro-grout. Next the murals conservators will restore the mural, include the damage from the injection ports.

In the field of historic preservation, we seem to love to tell people that the problem was caused by a mortar that was too hard and too strong, and that if only someone had used a softer, weaker mortar they would have avoided the present problem. At times that may be true – but certainly not always. My esteemed colleague David Hart of Salem, MA taught me something that Abbott Lowell Cummings taught him – in preservation, we should “Never say never, and never say always“.   My own experience in preservation has reminded me frequently of the wisdom of those words.

My initial surprise at the deterioration of the interior versus the exterior walls reminds me, and hopefully a few others, of a few things. While experience is invaluable, we should always try to approach our investigations with an open mind as to what the conditions, the problems, and their underlying causes, may be, and not allow our previous experience or an established canon to cloud (or even worse, serve as a substitute for) a detailed, open-minded investigation of the particular case at hand. If our findings on a particular case differ from our previous experience, or the conventional wisdom, so be it.  Each building tells its own truths, independent of our expectations and any established canon, if we are only willing to look closely enough, and allow ourselves to be surprised by the truths we find. During this holiday season, it shouldn’t be too hard for us to be willing to be surprised, and remember that a surprise isn’t necessarily a bad thing.

"Auguri" (best wishes) spelled out in the lights across Via San Dorotea in Trastevere

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