Rahmi AYDEMİR
Business Development Manager
Aydemirler A.Ş.
Generally speaking, when it comes to write for trade periodicals, which generally have a specialist audience, I always feel some sorts of challenges. It is relatively easier to make comments on our industry, either on economic aspects or production dynamics, whilst one is required to stay constantly up-to-date and keep closely abreast with the global developments.
I think that we surely need to isolate ourselves, even if just a bit, from the market conditions under stress due to the stagnation both in the local and global scale. In this article, we will go beyond the economy and factory, and dive into the journey of the cement, the major building block of our civilization.
Cement or Concrete has been the cornerstone of the human life or, precisely, the human settlement for around 5.000 years. However, the oldest known use of the limestone (a cement ingredient) for a structure dates back to 12.000 years ago. T-shape carved columns of Göbeklitepe are made up of limestone. It may be asserted that the main reason behind the transition of human society from nomads to settled societies is not the agriculture but the human’s desire to gather together and worship under a large building, as suggested by the historical temple.
Today, researchers plan to take the ancient technology to the space. Aiming at creating the space civilization, the initiative enabled scientists, for the first time, to mix the cement in the microgravity environment at the International Space Station (ISS). As part of the experiment called Cement Hardening/Microgravity Research, researchers sent ISS the basic ingredients such as cement-tricalcium silicate, wet limestone and purified water. The ingredients are then mixed in the bags and stored along the hydration process for 56 days to make it hardened (As the cement hardens throughout the hydration process, the molecules in the mix develop millions of microscopic crystalline. Such intermeshed crystallines help cement molecules create an interbond as well as bond with other cement ingredients such as gravel, sand and fine rocks.)
Results show that the cement mixed under the microgravity can actually be hardened just like it does in the Earth. However, space cement has also some unique microscopic properties, unlike the Earth-made cement. Interestingly, researchers discovered that the lack of strong gravity at the space station enabled the space cement have a surprisingly homogenous density. In addition, in the control experiment, when the space cement is returned to the Earth, it developed a more layered structure due to the gravityborne sedimentation. (Learning the differences between earthmade cement and space-made cement is important to reveal the effects of the gravity on the cement production process.)
While earth-cement (left) is exposed to the normal gravity, ISS cement (right) is left to hardening for 56 days under microgravity. Shell-like coarse features observed in the microgravity sample are the entrapped air bubbles causing the increased porosity (Porosity is a parameter which influences the water retention and transfer potential of the material. It is an indicator which shows how much a porous material can contain water.) J. Neves et al. (DOI: 10.3389 / fmats.2019.00083)
Since very beginning of the construction, especially for 1824, we have had no concerns with respect to the cement, apart from the recent ecological concerns. However, as the space age has arrived, we need to build structures which protect humans and equipment against extreme temperatures and radiation during the Moon and Mars missions. As is well known, concrete provides better protection than many materials and is the best radiation shield to store the nuclear waste away. (www.astronomy.com/ news/2019/09/first-cement-mixed-in space-paves-the-way-forotherworldly- buildings)
If humans are to build a Moon Village or a Martian colony in the years to come, we have to master on the extraterrestrial cement mixing.
