It is a well known fact that concrete is considered as the globally accepted construction material on earth. On the other hand, concrete in space was still mysterious when the researchers wrote this paper. However, some prior research indicated that there is possibility of lunar soil could be utilized as a construction material in space. A team of Master Builders, Inc. and Students for the Exploration and Development of Space (SEDS), a student group at the University of Alabama in Huntsville instigated such unique, ongoing, fundamental research program for concrete in space, particularly in moon. The researchers mainly focused research on hydration mechanism of Portland cement in microgravity and search out some potential improvement on earth concrete.
As mentioned in the paper, the research program was divided in to four major phases commenced from preliminary feasibility study of experiment to concluding testing and evaluation of intended material properties. In this study, finding prospective microgravity environment with enough time for experiment (basically for concrete mixing and curing) and flexible hardware interface for specialized experimental devices were the foremost challenges for the successful research. The author’s state that they explored four earth based microgravity environment from the different sources, NASA Space Shuttle was the most convenient one because it could provide sufficient time of microgravity environment for experiment and, fortunately, there was an additional NASA’s GAS (Gas Away Special) experimental program for the purpose of supporting use of space for all the researchers. After all, the researchers set the experimental program entitled as Conic (Concrete Curing and Mixing in Microgravity).
For such experiment, design of fully automated concrete mixing chamber in microgravity environment was the challenging task for the researchers although it is somewhat simple effort on earth. Reviewing the preceding research literatures and exercising many prototype models, eventually, they succeeded to develop a mixing chamber controlled by the microprocessor by means of autonomous specialized hardware system.
In this study, many experiments on earth confirmed that mortar was better than concrete regarding as block and jam action of mixing blades by coarse aggregate in concrete. Eventually, they established the most suitable design proportion of mortar as 1.25 parts type I portland cement, 1.25 parts ASTM C109 standard sand, 0.5 parts water and 8 floz/cwt of water reducing admixture.
Observing the experimental schedule in paper, it is seen that researchers have completed the entire task and looked forward for the final shuttle flight.
"Space Shuttle System Overview." NASA. Ed. Jim Wilson. NASA, 22 Aug. 2007. Web. 11 Apr. 2014.
Before going any further with this paper, I would like to take a moment to thank the crew of the space shuttle challenger for their bravery, courage, determinations and and sacrifice for this great nation. Francis R. Scobee (2), Commander, Michael J. Smith (1), Pilot Judith A. Resnik (2), Mission Specialist 1, Ellison S. Onizuka (2), Mission Specialist 2, Ronald E. McNair (2), Mission Specialist 3, Gregory B. Jarvis (1), Payload Specialist 1, Sharon Christa McAuliffe (1), Payload Specialist 2 (science.ksc), were parents, friends, children, husbands and wives, heroes, smart human being that were killed on this tragic day. May God be with your soul and may your memories and courage and passion shall not be forgotten but instead drive future generation determination and passion. The crash of the space shuttle
1. The first goal of the Space Shuttle program was to provide NASA with an efficient, reusable method of
The program is said to have a very high success rate, with few negative factors. In 2001 STS won the Presidents Award for its creativity, resourcefulness, effectiveness, and innovation.
NASA’s Space Shuttle Program has impacted the United State in many different way throughout history. When the first American shuttle was launched into space in the 1960’s, there was an explosion of ideas for NASA and for other countries throughout the world. When the Challenger and Columbia exploded, it showed NASA that there were things they had to change about their shuttles, and the design of them.
In this paper we have studied compressive strength of concrete by replacing natural aggregate with recycled aggregate by 25%, 50% and 75%.This mixture formed in the sample of cubes of dimension 150x150x150mm3.
Aitcin P.C, “Cements of yesterday and today Concrete of tomorrow”, Cement and Concrete Research, Vol. 30, (2000), pp 1349 - 1359.
NASA has built its newest space shuttle which is made to set records and take humans further than they have ever gone before to explore unmapped territory, asteroids, and the Red Planet, Mars. There was a test flight scheduled for this amazing machine to fly on Thursday December 4, 2014 but the launch time continued being delayed for multiple reasons. The new apparent launch date is Friday December 5, 2014 at 7:05 AM ET.
In figure (2.26), eight equations proposed by different researchers have been plotted for lightweight concrete, as shown in table (2.12). The experimental splitting tensile strength values are calculated as follows: Eq. (2.23), (2.24), (2.25) (2.26) for cube specimens and (2.27), (2.28), (2.29), (2.30) for cylinder specimens. The splitting tensile strength of lightweight concrete for Eq. (2.23) ranged from 2.8 – 3.5 MPa, as shown in figure (2.23).
Concrete behaves as a back bone to nations building team. Concrete is a composite construction material composed primarily of aggregate, cement, and water. There are many formulations, which provide varied properties. But one of the disadvantages with the conventional concrete is high self weight of concrete. This heavy weight will make it some extent uneconomical structural material. Many attempts made in the past to reduce the self weight to increase the efficiency of concrete.
Concrete is one of the most widely used construction material in the world. The reason for this is because concrete is strong, easy to make and can be molded into various shapes and sizes. Besides that, concrete is cheap, affordable and is readily mix.
Through investigating the various properties of Cement/Concrete/Mortar, Glass, and Ceramics/Porcelain I have come to understand the chemical composition, type of bond, structure, and the daily use of each of the substances. Cement is composed of calcium which usually is acquired from limestone and silicon which is usually from sand, shale or clay (aluminosilicates). The structure of cement is in between the two extremes of an ionic and a covalent model. It is between an ionic oxide lattice and a tetrahedral covalent network. Cement when wet or when dry has both cohesive and adhesive properties. Concrete is created through the mixture of cement (filler), fine and coarse aggregate (binder), and water. With the characteristics of these materials, concrete’s type of bond attributes to its high thermal insulation properties and the strength of the material itself. Concrete is used for building materials and due to its thermal insulation properties as insulators. Mortar is a mixture of cementitious materials, water, and aggregate. For commercial use in buildings and constructions, it is useful by having water retentivity and its strength after stiffening and hardening. In addition, the content in the mortar of cement as well as air content affects the strength of the tensile bond between the mortar and the masonry. Due to the materials that compose mortar, it developed a chemical structure that is similar to its components. Also, in daily use, mortar is used for construction for buildings to attach segments together.
In figure (2.26), eight equations proposed by different researchers have been plotted for lightweight concrete, as shown in table (2.12). The experimental splitting tensile strength values are calculated as follows: Eq. (2.23), (2.24), (2.25) (2.26) for cube specimens and (2.27), (2.28), (2.29), (2.30) for cylinder specimens. The splitting tensile strength of lightweight concrete for Eq. (2.23) ranged from 2.8 – 3.5 MPa, as shown in figure (2.23).
Overall, the Astronomy conversation was a success. Sharing of information led to new ideas and a great discussion on the future of space travel. All participants learned something new about the future of space travel. Last, it was obvious that regardless of age, education, or professional background, people are interested and excited about the future of space travel.
Relating to the Audience: I believe that the Space Shuttle program has fascinated most if not all of you at some point of time, so much so that it has driven some of us to pursue Aerospace Engineering. Thus, it is a good idea to explore the program’s end result, the reason why it was started in the first place – To build the International Space Station.