By Shaley Dawson in In the STEAM Community — Jan 20, 2023

Weekly Science News Recap

This weeks science news recap involves engineering, geology, and NASA stories from Jan 13, 2023 - Jan 20, 2023.

Denali fault trace cutting through Gakona Glacier, just after the 2002 earthquake. Tracks are from where geologists measured the fault offset. Photo: Peter Haeussler/U.S. Geological Survey.

On Tuesday:

Researchers with MIT and Harvard claimed to have discovered the secret to Rome's long lasting concrete and it may be simpler than we think. The team believed Roman's used quicklime in their concrete solutions, compared to the slaked lime used today. Quicklime is lime in its pure state and was found in distinctive chunks of white calcium carbonate in Roman concrete.

The test samples came from the archaeological site of Privernum, near Rome, Italy (A), and shown as a photogrammetry-based three-dimensional reconstruction (B). The architectural mortar samples were collected from the bordering concrete city wall (C). Large-area EDS mapping of a fracture surface (D) reveals the calcium-rich (red), aluminum-rich (blue), silicon-rich (green), and sulfur-rich (yellow) regions of the mortar. Further imaging of polished cross-sections (E) shows aggregate-scale relict lime clasts within the mortar (the large red features denoted by asterisks). The colored arrows in (E) denote the pore-bordering rings visible in the EDS data that are rich in calcium (red) or sulfur (yellow), which are enlarged at right to show additional detail. Photo credits (B and C): Roberto Scalesse and Gianfranco Quaranta, Associazione AREA3, Italy.

Originally thought to have been from poor mixing, the team examined the shape and crystine structure of the mixture. The team concluded that the deposits had been formed at extreme temperatures with a process known as hot mixing. It would be created by preparing the concrete with quickline, or calcium oxide, and in the process of 'hot mixing', heat would be released.

According to Massachusetts Institute of Technology (MIT) professor of civil and environmental engineering Admir Masic and his team, hot mixing creates a brittle nano-particulate form in the concrete. Once cracks form in the concrete, they fracture the clasts and when water reaches the particles, it creates a calcium-saturated solution that crystallizes in the cracks and "heals" them. The increased temperature from the hot mixing also reduces curing and setting times and reactions are accelerated.

Through the process of hot mixing, the calcium-rich lime clasts are encapsulated by the cementitious matrix, which, following the formation of a hydration rim, ultimately undergo carbonation (top row). Upon cracking (bottom row), water can infiltrate, transporting a calcium-enriched solution into the pore network to heal the damage (process 1) or serve as reactive calcium for post-pozzolanic reactions (such as C-A-S-H formation) at the interface between the volcanic tephra and the surrounding matrix (process 2).

To read the full study publihed by Masic and the team, click here: https://www.science.org/doi/10.1126/sciadv.add1602#

On Wednesday:

Brown researchers may have discovered the secrets of how Denali's fault formed. The 1,200 mile long strike-slip fault arcs across Alaska and Canada and was the site of a 7.9 magnitude earthquake in 2002.

Brown University seismologists analyzed part of the fault near the surface that connects to the base of the tectonic plate and found changes in thickness and strength of the 2 plates. Researchers created a 3D model of seismic wave velocities throughout Alaska. The model displayed a difference in tectonic plate strength as far down as almost 50 miles. This feeds back into the mechanics of the Denali fault line and how it is produced. They discovered the fault forms due to an increase in strength on the northern side of the fault that goes all the way through the upper plate. By understanding how geologic forces behave, it can help future researchers make better assessments and develop better models on strike-slip earthquakes.

The new study in Geophysical Research Letters shows a previously undiscovered change in tectonic plate thickness across the Denali Fault in Alaska impacts where it is located, shedding light on how major faults and earthquakes occur. Credit: Isabella Gama and Karen Fischer.

To read more about the Denali fault discovery, click here: https://www.brown.edu/news/2023-01-18/denali-fault

On Wednesday:

NASA announced the organization had issued an award to Boeing for their Sustainable Flight Demonstrator Project. Over the next seven years, NASA plans to work with Boeing to create a full scale demonstrator airline equipped with new technologies aimed at lowering emissions.

Through the Sustainable Flight Demonstrator project, NASA and Boeing will work to develop a full scale Transonic Truss-Braced Wing demonstrator aircraft. The concept involves an aircraft with extra-long thin wings stabilized by diagonal struts; which becomes more fuel efficient due to the aerodynamic structure, resulting in less fuel burning. NASA hopes to complete testing for the project in the late 2020s, so the next generation of single aisle aircraft could enter into service in the 2030s.