BUILDING ROMA AETERNA MORTAR DATING AND ROMAN POZZOLANA

BUILDING ROMA AETERNA MORTAR DATING AND ROMAN POZZOLANA, RESULTS AND INTERPRETATIONS

Diagram of Mortar samples from the Åland Islands, 140 samples Correct or plausible results 81, 4% Correct results Plausible results Results wrong, but reason known Wrong results

Åland mortars from securily dated structures, compared to dendrochronologi and 14 C dated wood structures A total of 50 samples 42 correct 84% 5 wrong, but reason known 10% 3 results wrong 6%

Sampling at the Roman villa of Torre de Palma Portugal was done in 1997 -2000. It resulted in a chronology of the site Beginning with The East Bath in the first century AD

Ending with the large font of the Baptistery

Rome Samples from Trajan’s market, from 1999 and Hadrianic Samples from Ostia

Carolingian construction at Nerva’s Forum, analyzed in two fractions in 1998. Result of the first fraction plausible.

Santo Urbano, excavated under Via dei Fori Imperiali

Trajan’s Forum, Basilica Ulpia, calibrated result 60 AD-140 AD

Rome, Torre delle Milizie, analyzed in Aarhus in two CO 2 fractions, and in Oxford in five. Calibrated age To begin with, in 1998, three samples from Torre delle Milizie were analyzed in two AD 1260 -1285. CO 2 fractions in Aarhus

Sample Rome 007 was later analyzed in five fractions by The Oxford Radiocarbon Accelerator Unit. It confirmed the results yielded by the first fractions. Calibrated age: Ca 1205 AD-1260 AD

The Colosseum, erected ca 80 AD, four different profiles agree on the first fractions with the estimated age

The temple of Jupiter Anxur, Terracina

Sampling at Terracina, a candidate for early pozzolana, from a spot which had been exposed to maximal erosion. The concrete still had imprints of the wooden moulding construction. Not hydraulic according to the hydraulic index. It reached a plausible age with the first CO 2 fraction of the profile.

The identical sample from the harbour construction at Portus, plausible result revealed at the joining point between the two profiles, one from Oxford and the other from Aarhus.

Pompeii, Casa di Marcus Lucretius, sampling in Collaboration with the EPUH (Excavationes Pompeii Universitatis Helsinkiensis). All samples from Pompeii and Herculaneum went wrong

The Suburban Baths at Herculaneum, with optimistic group in May 2006. . .

The horse-shoe shape Basilica of Sant’Agnese, founded by Constantine the Great, during the pontificate of Silvester I (314 -335 AD). The rotunda of Santa Costanza is not bonded with Sant’Agnese, and the pozzolana concrete is very different. Controversial date of Santa Costanza: a) Between 337 -351 built by Constantina, daughter of Constantine the Great b) later half of the 4 th C. C) around 400 AD.

Rome 017, Santa Costanza, 14 C AMS-analysis perfor-med in Aarhus, calibrated result, AD 330 -390.

However, an independent source seems to support our initial results. 14 C AMSanalysis of the wood ashes embedded in the mortar of the foundation of Santa Costanza has been implement, with interesting results. According to David J. Stanley, who had wood ashes embedded in the concrete at the foundation level of Santa Costanza dated with 14 C –analysis, the result yielded was AD 412 ± 43, or 369 -455 AD (David J. Stanley, 2004). However, using mechanical calculation with ± 43 as margin errors, can be problematic. To reach the suggested date the uncalibrated BP age of 1632± 43 comes close, without being identical. The original BP age, is at present unknown.

Further samples from Santa Costanza were analyzed to confirm the earlier result. The first 14 C fraction of Rome 046 does coincide with the earlier plateau, but the profile of Rome 042 is just strange. A narrow horizontal line along the agreeing fractions can, with good will, suggest the date of AD 340 -395.

The results of two samples of three from Sant’Agnese look even more problematic

Sant’Agnese: the interpretation of the results suggests two possible dates, one too ancient and the other one too recent Delta 13 C values of samples from Santa Costanza and Sant’Agnese Possible explanations: bad sampling! a) Re-crystallization with rejuvinating effect on 044 b) The Delta 13 C value of Rome 043 is different from the others, and anomal 18 O delta values of the sample may indicate that something could be wrong with the ancient horizontal level of the profile.

Diagram of all mortar samples, Classical and Medieval 1. Correct results 2. Plausible results 3. Results wrong, but reasons known 3. Results wrong

Statistical diagram from Torre de Palma, non-hydraulic Classical mortar, 65 samples analyzed in two fractions Correct or plausible 83% Plausible Wrong, but reason known Wrong

Diagram of Pozzolana mortars, 63 samples Pozzolana mortars Correct: 19 samples Plausible: 14 samples Correct or plausible 52 % Wrong but reasons known: 19 samples Totally wrong: 11 samples

Pozzolana mortars, results wrong, reasons known 1. Buried under volcanic ashes 2. Too few fractions dated 3. Crushed bricks in the aggregate 4. Bad sampling (secondary repairs) 5. Delayed hardening

11 samples went wrong without us as yet understanding why. However – as a rule samples that go wrong are easily recognized, even if the patterns may vary 1) The profile created no horizontal plateau 2) All the fractions yielded different results, all of them too recent In three cases horizontal plateaux were created in the wrong place of the profile, either far too recent or far too ancient, or possibly correct, secondary repair!

The team, in different constellations, trying to work out how to proceed with pozzolana mortars