Contents lists available at ScienceDirect Journal of CO 2 Utilization journal homepage: www.elsevier.com/locate/jcou Review Article Potential of CO 2 sequestration through construction and demolition (C & D) waste—An overview Senthil Kumar Kaliyavaradhan, Tung-Chai Ling ⁎ College of Civil Engineering, Hunan University, Changsha, 410082, China ARTICLE INFO Keywords: Active carbonation CO 2 curing Recycled concrete aggregate Waste cement Concrete block ABSTRACT Carbon dioxide (CO 2 ) is the predominant greenhouse gas on Earth and its atmospheric concentration is in- creasing at an exponential rate due to human activities. Cement production contributes about 7% of the total worldwide CO 2 emissions, and thus finding a practical way to reduce the greenhouse gas emission is essential. Construction and demolition (C & D) waste rich in calcium hydroxide and calcium silica hydrate is considered to be a potential calcium source for CO 2 sequestration, forming thermodynamically stable carbonate minerals. In the past decade, a major research effort was to study the influencing factors affecting the effectiveness of active carbonation of C & D waste. In this paper, active carbonation techniques adopted for crushed concrete aggregate and waste cement derived from the C & D waste, and the resulting properties of the CO 2 cured concrete aggregate and cement waste are discussed. In addition, special features of concrete block products as a potential medium for CO 2 sequestration are also highlighted. Lastly, based on the environmental benefit and cost analysis of CO 2 sequestration through C & D waste and concrete block are also presented. We concluded that the mineral car- bonation of C & D waste is technically feasible, economical and environmentally friendly approach of a future carbon sequestration strategy. 1. Introduction Greenhouse gases are responsible for the existence of life on earth. In the 18th century, environmental scientists named the natural process which keeps the earth warm and maintains ecological balance through greenhouse gases called the greenhouse effect [1]. In the past few decades, the greenhouse effect has been viewed in terms of negative connotations because of global warming and global climate change. The major greenhouse gases responsible for global climate change are water vapour (H 2 O), carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), chlorofluorocarbons (CFCs) and ozone (O 3 ) [1]. Among the greenhouse gases, CO 2 is the largest single source comprising about 76%, and the average lifetime of CO 2 in the atmosphere is thousands of years [2,3]. It has been reported that the atmospheric concentration of CO 2 has increased by more than 40% from the preindustrial era (about 280 ppm) to 406.42 ppm in February 2017 [1,4]. Now the atmospheric CO 2 acceleration is at an unprecedented rate of 2.2 ppm per annum, and the earth is expected to warm by 2 °C–3 °C when CO 2 concentra- tions reach about 450 ppm by 2050 [4]. This will in turn increase the global average temperature, melt ice in the polar regions, raise sea le- vels, cause changes in the pattern and amount of rainfall, cause changes in snowfall pattern, more droughts, less agricultural yield, an increased pollutant concentration in the air, changes in relative humidity, ex- tinction of flora and fauna, etc. [1]. The power generation and cement production sectors are the two main industries contributing to global CO 2 emission. The cement in- dustry alone has contributed about 7% of global CO 2 emission [5]. Limestone (CaCO 3 ) is calcined to lime (CaO) under a thermal decom- position reaction and produces a large quantity of CO 2 (see Eq. (1)). Hence, production of one tonne of clinker produces approximately 0.51 t of CO 2 due to the calcination process, and addition of CO 2 is generated from the burning of fossil fuels in the production of cement clinker and the grinding process [6,7]. In summary, production of 1 kg of Portland cement generates > 0.8 kg of CO 2 . CaCO 3 + heat → CaO + CO 2 (1) The world’s cement production is increasing by 2.5% annually, and a total of 4.6 billion tonnes of cement was produced in the year 2015 [8,9]. It was reported that about 50% of world cement production takes place in China, followed by India (5.9%), the USA (1.8%), Japan (1.3%) and other countries [9]. In China, India, and North America the carbon intensity is about 10% higher than the average [10]. Considering the high CO 2 emissions and environmental challenge, the cement industry is the foremost area to take action to reduce greenhouse gas emissions http://dx.doi.org/10.1016/j.jcou.2017.05.014 Received 7 April 2017; Received in revised form 8 May 2017; Accepted 20 May 2017 ⁎ Corresponding author. E-mail addresses: senthilkumark13@yahoo.com (S.K. Kaliyavaradhan), tcling@hnu.edu.cn, tcling611@yahoo.com (T.-C. Ling). Journal of CO₂ Utilization 20 (2017) 234–242 2212-9820/ © 2017 Elsevier Ltd. All rights reserved. MARK