ISSN 1063-7729, Astronomy Reports, 2016, Vol. 60, No. 2, pp. 306–312. c  Pleiades Publishing, Ltd., 2016. Lunar Concrete: Prospects and Challenges * Anwar Khitab ** , Waqas Anwar, Imran Mehmood, Syed Minhaj Saleem Kazmi, and Muhammad Junaid Munir Department of Civil Engineering, Mirpur University of Science and Technology, Mirpur, Azad Jammu & Kashmir, 10250 Pakistan Received April 20, 2015; in final form, June 26, 2015 Abstract—The possibility of using concrete as a construction material at the Moon surface is considered. Dissimilarities between the Earth and the Moon and their possible effects on concrete are also emphasized. Availability of constituent materials for concrete at lunar surface is addressed. An emphasis is given to two types of materials, namely, hydraulic concrete and sulfur concrete. Hydraulic concrete necessitates the use of water and sulfur concrete makes use of molten sulfur in lieu of cement and water. DOI: 10.1134/S1063772916020050 1. INTRODUCTION Concrete as a construction material has been used at least as far back as the Roman and Egyptian empires. Modern concrete is defined as a mixture of cement, water, aggregates, and in some cases, admixtures and additives [1]. Concrete is a versatile construction material and has strength, durability, versatility, and economy. It can be placed or molded into virtually any shape and reproduce any surface texture. With proper materials and techniques, concrete can withstand many hostile environments. Since concrete is a structural material, strength is a desir- able property. Although the compressive strengths of ordinary concrete generally range from 15 to 40 megapascal (MPa), concrete can be made to withstand over 80 MPa for special tasks [2]. It is for these reasons that it is considered to be the first lunar construction material. 2. HISTORY OF SPACE EXPLORATION The first proposal to reach the outer space came through the Soviet scientist Konstantin Tsjolkoysky in his article “The Exploration of Cosmic Space by Means of Reaction Devices,” published in 1903 [3]. Then R. H. Goddard presented his paper, “ A method of reaching extreme altitudes,” in 1919 [4]. A first rocket to reach the space was the V-2 rocket, launched by the Germans during the World War II [5]. Yuri Gagarin was the first cosmonaut to reach ∗ The text was submitted by the authors in English. ** E-mail: anwarkhitab@yahoo.com,chairman.ce@must. edu.pk the upper space in 1961. Neil Armstrong was the first man, who has landed on the Moon surface along with Buzz Aldrin in 1969. Since 1969, some twelve landings have been made by the Soviets and US at the Moon surface along with plentiful scientific operations therein. Conquering the space, a man also had a vision to make colonies at some planetary body outside the Earth. Because of its proximity to the Earth, the Moon is considered to be the first choice of hu- mankind. This factor is very important in the sense that lesser energy is be required for transport to and from the Moon. Its second advantage lies in the fact that the Moon possesses some gravity, approximately one sixth that of the Earth. Thirdly, the Moon has plenty of natural resources, which could be of great benefit to mankind [6]. Fourthly, it would cost less to send space vehicles to other planets from the Moon than from the Earth [7]. But not all is well with the Moon. There are certain consequences, too, which must be addressed. Although lunar gravity is an advantage, it is also a great disadvantage. Lunar day equals some twenty nine Earth days. Lunar atmosphere is much thinner than that of the Earth, providing almost no protection against radiation [8]. Last but not the least, there is a serious debatable question as how the humans will psychologically re- act to an alien environment of the Moon. Despite all ifs and buts, the truth is that mankind is advancing in its pursue to colonize the Moon as per famous saying of Frederick Douglass “without a struggle, there can be no progress.” 3. EARTH AND MOON: DISSIMILARITIES The Moon offers hard vacuum of free space and is also deprived of hydrolytic weakening process. This 306