Week 22 – Carnevale Romano, Super Bowl Monday, and the Comparative Durability of Masonry Materials at Ercolano

Scene from Carnevale Romano - Performers entertain a crowd at the Piazza di Spagna, at the base of the Spanish Steps

We’re in the midst of Carnevale season in Rome. Carnavale is the entire season leading up to Lent, culminating the final day before lent (best known in English as Mardi Gras, from the French “Fat Tuesday”.) The name Carnevale, which includes the Italian word for meat (Carne), reflects the last chance for eating meat (and engaging in other indulgences) before lent. The revival of Carnevale celebrations in Rome is fairly recent – these celebrations were banned in Italy by Mussolini in the 1930’s and 40’s.

The Carnevale celebrations here in Rome aren’t as artistically elaborate as those in Venice, nor as wild and adult-oriented as those in New Orleans. From what I’ve seen thus far, Rome’s Carnevale seems to involve a lot more family fun – kids in costumes, jugglers, performing arts, etc., – than wild debauchery.

Carnevale Romano - swashbuckling pirates...

...a maiden...

and Snow White all climb atop the lion fountain in Piazza del Popolo

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To compare it to two celebrations I’ve attended numerous times, Rome’s Carnevale is more similar to Boston’s First Night New Year’s celebration than it is to Carnival season in New Orleans. 

a pumpkin-monster takes a break at Piazza Navona. It must be tiring being that cute all the time - people expect you to always be "on".

My bear cub daughter reaches out a paw to befriend a kitten, as Zorro looks on

Confetti on the pietrini paving in Rome after a Carnevale celebration

Speaking of New Orleans, early this morning, I and many others here at the American Academy experienced our first ever “Super Bowl Monday”. About a 15 of us piled into a small lounge with a television in the McKim Mead and White building to watch the game live, which meant it started at 12:30 AM on Monday morning (and ended about 3:30 AM). Our crowd consisted of a mix of about a dozen Americans, a few Italians, 1 Brit, and 1 Dutch woman, but oddly, we were all rooting for New Orleans. We feared that we might have awakened the saner people in the bldg, asleep in their apartments, when we all erupted raucously around 3:30 A.M. when New Orleans returned an interception for a touchdown to clinch the victory.  

The archaeological site at Ercolano (Herculaneum), with the volcano Mt. Vesuvius looming in the background. If you drew two imaginary lines extending the far right slope of the right peak, and the far left slope of the left peak, to connect them at a single point well above the present peaks, basically at the top of this photo, you'd draw the approximate triangular outline of Vesuvius before the eruption in 79 A.D. The missing material was deposited all over this region by the eruption, burying sites like Ercolano and Pompeii 10-60 feet deep.

Last week I made my third visit since November to Ercolano Scavi (the Ercolano excavations), one of my ongoing study sites. It’s an archaeological site on the coast of the Bay of Naples near Mt. Vesuvius that, like the more famous Pompeii, was buried by the eruption of Mt. Vesuvius in 79 A.D.  Ercolano, called “ Herculaneum” in English, is named for the Greek god Hercules. I’ve been to both Ercolano and Pompeii, but Ercolano  is much more interesting to me.  I’m deeply interested in the details of construction, and Ercolano is a better place to see those details, because the construction is generally much more intact than at Pompeii.   As a result of  the different way the two were buried by the eruption (Ercolano by a pyroclastic flow, Pompeii by a shower of ash), Ercolano has intact (on some buildings) upper stories, roofs, wood framing, and even some wood furniture, whereas the remains at Pompeii mostly consist of first story masonry walls. If you are interested in architecture and construction, and you visit the Bay of  Naples, I definitely recommend you visit Ercolano.

1st century A.D. streetscape in Ercolano

 Although I’ve been fortunate enough to gain access to some restricted parts of the site for research on my project (thanks to the people at the Herculaneum Conservation Project), one of the most interesting phenomena I’ve observed regarding durability is readily visible all across the public access areas of the site. It’s the phenomena of the severe “rising damp” (wicking of moisture from below grade) on masonry walls across the site, and more interesting still, the way that allows us to compare the relative durability of the various masonry materials used in constructing those walls.

Classic rising damp problem at Ercolano. Note how the band of wetness roughly follows the slope of the ground. The wetness, zone of drying, and efflorescence extend through the brick, and above, but the brick and original mortar have proven much more durable under this torture test than the original tufa.

As a bit of background, the site was buried by as much as 60 feet of material by the eruption of Vesuvius, so the excavation is now a very deep hole 40-60 feet below the present grade of the modern city. The current depth of the ancient city, compared with the depth of grade of the surrounding modern city, has created high groundwater levels within the site, and severe “rising damp” phenomena for the masonry walls down in the archaeological site. Because this condition is more severe than it was originally within the ancient city, and because the ancient city was buried for so many centuries, we can’t really compare the condition or durability of the masonry walls here to other sites.

But what we can do is compare the various materials within the same wall (brick, mortar, and 2 types of tufa) to each other, to compare their relative durabilities.    Since the various materials within the same wall have been subjected to the same conditions, mother nature has essentially been torture-testing these masonry materials, and we can walk the site and read the results for ourselves.

tufa is more deteriorated than brick

mortar and brick are both more durable than the old tufa

Brick more durable than tufa

Old tufa (diamond shape) more durable than new tufa (polygonal shape)

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Examining these walls tell us that under these conditions (rising damp, with salt-laden moisture, and consequent efflorescence and subflorescence), these materials rank in the following order from most to least durable:

• brick

• mortar

• yellow tufa (the original stone, from Mt. Vesuvius, the local volcano)

• yellow tufa (the replacement stone used in localized repairs, from Campi Flegrei, a volcano on the other side Naples)

The durability of the original mortar is particularly remarkable. Of course, it’s the pozzolana from volcanic soil and ash that made Roman mortars (and Roman concrete) so strong and durable.  Many of us who practice in places like the mainland U.S. and the U.K. where we aren’t exactly surrounded by volcanoes (and hence, we aren’t surrounded by pozzolana), might be shocked to see an ancient historic mortar outlast a natural stone in a masonry wall, as we see here in the Bay of Naples – both at Ercolano and at Pompeii.

Original mortar outlasting original tufa under rising damp conditions

Seeing photos like these without any explanation, and outside of their context, it would be easy for someone to (incorrectly):

• assume the mortar is a 20th century Portland cement-lime-sand mortar,

• assume the mortar was “too hard” and “too impervious”, and

• some might even assume that the hard mortar caused the deterioration of the stone.

However, none of these assumptions would be correct.

All of this reminds me of the lessons learned that I summarized in my Week 13 post. The Week 13 post discusses durability relating to hard versus soft mortars (albeit on a building from the 18th century, not the 1st century A.D.)  and some of the oversimplified preservation rules of thumb (sic: very hard mortar is always bad and always modern; and historic mortar is soft, which is always good) that I and so many others were taught in school, or in practice.   My observations of the tufa, the brick, and the mortar at Ercolano again reminds me of the importance of coming to the jobsite with an open mind, let the building tell its own truths, and in preservation, “Never say never, and never say always”.