Why was Roman Concrete Forgotten during the Middle Ages?

YouTube ^ | November 12, 2021 | toldinstone channel

[SunkenCiv]

For centuries, concrete was everywhere in Roman Italy: in the awesomely durable breakwaters of artificial harbors, in the soaring vaults of great baths, in the foundations of the Colosseum, and - of course - in the spectacular dome of the Pantheon. But during late antiquity, concrete all but vanished from the Mediterranean world, and would not be used widely again until the twentieth century. This video explains why.

Chapters:
0:00 Introduction
0:39 Understanding Roman concrete
1:29 Early experiments
2:25 The apogee
3:33 Squarespace!
4:19 Geographic limits of Roman concrete
5:00 The decline of concrete
6:28 Final notices
7:26 Not forgotten, but gone

Why was Roman Concrete Forgotten during the Middle Ages? | November 12, 2021 | toldinstone

[PIF]

Caesar Antony is given first credit, while the muslims got the rebuilt collections later

[Paladin2]

SALT LAKE CITY, UTAH—Modern concrete, when placed in the presence of sea water, erodes over time. According to a report in BBC News, scientists led by Marie Jackson of the University of Utah examined samples of ancient Roman concrete from ancient harbor structures with an electron microscope, X-ray micro-diffraction, and Raman spectroscopy in an effort to learn why it gained strength from exposure to sea water. The tests, conducted at the Lawrence Berkeley National Laboratory, revealed crystals of a rare mineral known as aluminum tobermorite growing throughout the samples of concrete, in addition to a porous mineral called phillipsite. The mineral crystals continued to grow in the Roman mix of volcanic ash and lime, which reinforced the concrete over long-term exposure to sea water. A similar chemical reaction has been detected in underwater volcanoes. “Their technique was based on building very massive structures that are really quite environmentally sustainable and very long-lasting,” Jackson said. To read in-depth about how Romans used concrete, go to “Rome’s Lost Aqueduct.”

https://web.uvic.ca/~jpoleson/ROMACONS/Caesarea2005.htm

https://www.archaeology.org/news/5710-170705-roman-ocean-concrete

[SunkenCiv]

Did you ever consider that maybe they *liked* tossin’ their bedpans onto the passersby? ;^)

[thesearethetimes...]

🙃
Thank you both!
Tatt

[SunkenCiv]

[virtual ticker tape parade for bh7]

[SunkenCiv]

[snip] Suetonius relates that an inventor approached the emperor with plans for a hoisting machine that would greatly reduce the need for manpower but was rebuffed with the reply, “I must feed my poor.” Vespasian feared the machine would exacerbate unemployment in a society already overrun by idlers and slaves. Labor saving devices such as the water wheel were not wanted and consequently were neglected until there was a significant decline in both the general population and the number of slaves late in the 4th century. But a society that does not use its inventors will eventually lose its inventors. [/snip]

Stanley David Gedzelman, The Soul of All Scenery: A History of the Sky in Art, link, see Chapter 3

http://www.sci.ccny.cuny.edu/~stan/skyart.html

https://arsendarnay.blogspot.com/2012/05/vespasian-jobs-over-machines.html

[SunkenCiv]

LOL

[SunkenCiv]

After they started saving big money at Menardus’.

[SunkenCiv]

https://en.wikipedia.org/wiki/Portland_cement

[modern] https://en.wikipedia.org/wiki/Roman_cement

https://en.wikipedia.org/wiki/Roman_concrete

[SunkenCiv]

My pleasure.

[SunkenCiv]

Thanks!

https://freerepublic.com/focus/chat/4012697/posts?page=42#42

[Paladin2]

“Rome wasn’t sacked in a day....”

[OldWarBaby]

Brits? Romes? yeah they were pretty good but so were the pre-Egypts. We still don’t know how to build a pyramid. And numerous samples of pyramid stone show tiny sea shells. Could very well be aggregrate. And the early S. Americas knew how to mold stone either by casting or some hot process which we can’t do?

A huge factor in the demise of Roman style aggregate was the slow disappearance of slave labor to make the crushed rock. The industrial grade rock crusher hasn’t been around long. The necessary steel didn’t exist. I know of a 19th century monastery built so that the monks could pack rocks up about 3 stories then drop them to break them into aggregate. One can’t use just any old rock to make spec concrete——dense, no porosity, high compression strength, etc.

[Paladin2]

“

Introduction

Ancient Roman concrete, an extraordinarily durable, high-performance composite constructed from lime and pyroclastic rocks, provides a unique temporal window to address shortcomings in modern concrete longevity and environmental sustainability. The monuments of Rome, such as the Markets of Trajan (96 to 112 CE), are masterpieces of concrete engineering in architectural settings (Jackson et al. 2009, 2010; Brune and Perucchio 2012). Roman builders also constructed massive, enduring concrete structures in harbors along the central Italian coast (Fig. 1) and Mediterranean region (Oleson et al. 2004). They designed the seawater concrete so successfully that it “can neither be dissolved in the waves, nor by the power of water” [Vitruvius, de Architectura, 30 BCE ( Appendix 1)]. The economic and military success of the expanding Roman empire depended on these ports, whose concrete structures have remained cohesive and intact while partially or wholly immersed in seawater for 2000 years. Romans mixed lime with pumiceous volcanic ash with seawater (Fig. 2) and packed this with decimeter-sized chunks of zeolitic tuff into underwater forms (Oleson et al. 2004). The ash, lime, and seawater reacted to produce poorly crystalline calcium-aluminum-silicate-hydrate (C-A-S-H) binder, intermingled with altered pumice and glass relicts in a complex cementitious matrix, which includes 11 Å Al-tobermorite (where Al3+ substitutes for Si4+) in relict pebble lime clasts (Barnes and Scheetz 1991; Vola et al. 2011a; Stanislao et al. 2011; Jackson et al. 2012).

Preliminary studies of drill cores from piers, breakwaters, and fishponds along the central Italian coast (Fig. 1) indicate that the Al-tobermorite, identified through standard X-ray diffraction analysis, developed diagenetically in all the concretes while they were immersed in seawater (Jackson et al. 2012). It forms <10 vol% of most mortar fabrics. The longevity and cohesion of the seawater concrete apparently lies in Romans’ selection of pozzolanic pyroclastic rock, preparation of lime, installation techniques in immense piers and breakwaters—and the exceptional stability of the C-A-S-H binding phase. Mineralogical analyses of cores from 11 Roman harbors drilled by the ROMACONS project between 2002 and 2009 and descriptions of the concretes by Vitruvius, writing at about the same time as the construction of the Pozzuoli Bay harbors, and Pliny the Elder (Naturalis Historia, mid-first century CE) suggest that the pumiceous pozzolan (pulvis) originated from deposits surrounding the Bay of Naples (Fig. 1; Appendix 1) (Granger 1931; Rackham 1952; Oleson et al. 2004; Vola et al. 2011a; Stanislao et al. 2011; Jackson et al. 2012). A pozzolan is a siliceous and/or aluminous material, named after ash from Pozzuoli (Fig. 1), which reacts with lime or lime-based compounds in the presence of moisture at ordinary temperatures to produce compounds with cementitious properties (Massazza 2004). Flegrean Fields pozzolan, known in Italian as pozzolana, is mainly excavated from deposits of the Fondi di Baia and Bacoli volcanoes (near Bacoli; Fig. 1). It is composed of pumices, lithic fragments, K-feldspar, and a poorly consolidated altered vitric matrix with variable quantities of authigenic zeolites (de’Gennaro et al. 2000). The ash has mainly trachytic compositions on the total alkali-silica (TAS) classification diagram; glassy components may exceed 90% by volume (Stanislao et al. 2011; Fedele et al. 2011). The trace element provenance of the pumiceous component of the ancient ash pozzolan has not, however, been determined.

Conventional concretes typically consist of ordinary Portland cement (OPC), a crystalline, finely ground material derived from clinker calcined at 1450 ºC, relatively inert sand and coarse aggregate, admixtures, and water that is pumped in a fluid state into forms (Taylor 1997). The concrete sets in a few hours, and hardens over a few weeks as OPC hydrates to form various compounds, mainly poorly crystalline calcium-silicate-hydrate (C-S-H), which bind the sand and coarse aggregates. Environmentally friendly concretes that partially replace kiln-fired Portland-type cement with supplemental cementitious materials, such as fly ash and blast furnace slag, and volcanic ash (Massazza 2004; Sun et al. 2006; Lothenbach et al. 2011), reduce fuel consumption and CO2 emissions associated with production of Portland cement, while producing good ultimate strengths and longevity, even in tidal zones (Massazza 1985; Mehta 1990; Thomas et al. 2012). The poorly crystalline C-A-S-H binders of these concretes improve chemical stability relative to C-S-H, the “glue” of conventional Portland-type cement concretes, whose model basis is the ideal composition of tobermorite, Ca5Si6H2O18·4H2O (Taylor 1992; Sun et al. 2006). C-A-S-H and 11 Å Al-tobermorite hold great potential as cementitious binders for high-performance concretes and concrete encapsulations of hazardous wastes (Komarneni and Roy 1983; Komarneni et al. 1987; Komarneni and Tsuji 1989; Tsuji et al. 1991), but the long-term performance of C-A-S-H is unknown and neither pure tobermorite nor Al-tobermorite occur in moist air-cured conventional concretes. Although laboratory syntheses of Al-tobermorite typically require high temperatures, 120 to 240 ºC (Diamond 1966; Komarneni and Roy 1983; Komarneni and Tsuji 1989; Barnes and Scheetz 1991; Shaw et al. 2000; Sun et al. 2006; Houston et al. 2009), occasional syntheses have been achieved at 80 ºC with amorphous silica and zeolites (Komarneni and Roy 1983; Komarneni et al. 1985), reactants similar to zeolitized alkali- and alumina-rich Flegrean ash pozzolan (de’Gennaro et al. 2000).

This study analyzes some of the mineralogical properties of C-A-S-H and Al-tobermorite in a concrete breakwater, or pilae, constructed in Pozzuoli Bay (Baianus Sinus) in first century BCE, now submerged under ~3.5 m of seawater. It integrates interdisciplinary findings from mineral physics, geochemistry, engineering, and archaeological science to investigate why Roman builder’s 2000-year-old natural experiment could produce crystalline Al-tobermorite but conventional concretes cannot. First, the occurrence of C-A-S-H and Al-tobermorite in relict lime clasts is described. Second, the volcanic provenance of the glassy tuff and pumiceous pozzolan is identified through trace element analyses. Third, the nanoscale bonding environments of Al3+ and Si4+ in Al-tobermorite and C-A-S-H are described with synchrotron-based scanning transmission soft X-ray microscopy (STXM) analysis and nuclear magnetic resonance (NMR) studies. These results provide an analytical framework to compare the compositions of Al-tobermorite syntheses from Baianus Sinus and Portus Neronis, the harbor concrete at Anzio (Fig. 1), with geologic Al-tobermorite {[Ca4(Si5.5Al0.5O17H2)]Ca0.2·Na0.1·4H2O (Taylor 1992)} from hydrothermal environments. The silica and alumina bonding environments of the C-A-S-H and Al-tobermorite are then compared with young laboratory syntheses. Next, the mix design of the Baianus Sinus concrete is determined as weight percent lime and pyroclastic rock through macroscopic observations of the present concrete fabric and ancient texts. This information is used to compute the thermal history of the 10 m2 by 5.7 m thick pilae, where adiabatic time-temperature profiles are calculated from an estimation of heat evolved during formation of C-A-S-H to identify the maximum temperature at which Al-tobermorite crystallized. Finally, the lime-seawater-volcanic ash mix design and massive scale of the Roman seawater concrete constructions are discussed as determining factors in generating temperatures sufficient for large-scale synthesis of the crystals. These observations advance an ancient concept of concrete produced with lime and pyroclastic rock, which opens future perspectives for producing Al-tobermorite in the context of highly durable concrete structures with volcanic pozzolans.
“

https://pubs.geoscienceworld.org/msa/ammin/article/98/10/1669/45726/Unlocking-the-secrets-of-Al-tobermorite-in-Roman

Sounds like some good work has been done.

[Spacetrucker]

Hey, yous, Guido is a gonna stop over at your place and have a chat, see?

[GreenHornet]

Hey, yous, Guido is a gonna stop over at your place and have a chat, see?

"Nice Colosseum ya got there.....be a shame if something were to happen to it."

[Sequoyah101]

It was causing globull warming and they banned it and used mud blocks instead because they were sustainable and renewable.

[normbal]

If the ‘slims took credit, I’d believe them.

https://www.dailyhistory.org/How_was_the_Library_of_Alexandria_Destroyed

[Right_Wing_Madman]

Vespasian feared the machine would exacerbate unemployment in a society already overrun by idlers and slaves.

Also, Professor Peter Green points out in Hellenistic History and Culture:

It's not so much that slaves were available, which indeed they were. No, the ruling classes were scared, as the Puritans said, of Satan finding work for idle hands to do. One of the great things about not developing a source of energy that did not depend on muscle power was the fear of what the muscles might get up to if they weren't kept fully employed.

[Deaf Smith]

"but last 2000 years"

Those house sized concrete bases of the wind turbines may put that to the test.

Long after wind turbines are removed due to loss of government subsides.