Prof. Caijun Shi is currently the president of Asian Concrete Federation, Chair Professor of the College of Civil Engineering, Hunan University, Director of Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education of China, Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, and International Science and Technology Innovation Centre for Green & Advanced Civil Engineering Materials of Hunan Province. He is the founding Editor-in-Chief of <Journal of Sustainable Cement-based Materials>, and associate editor or editorial board members of many other journals.
He has authored/co-authored more than 540 technical papers, seven English books, five Chinese books and edited/co-edited seven international conference proceedings. His Google scholar citation is over 33,800 and H-index of 95 (by Jan 20, 2023). He ranks No. 2 for year 2022 and No.4 between year 1969-2021 in Building and Construction Sector worldwide based on the composite index from Stanford University. He has delivered over 240 plenary/keynote/invited lectures all over the world, including three keynote lectures at the previous International Congress on the Chemistry of Cements, has received many awards for his researches. He has developed several commercialized novel technologies and products and has been granted 4 US and 50 Chinese patents, and was elected as a fellow of International Energy Foundation in 2001, American Concrete Institute in 2007, RILEM in 2016, and Hongkong Concrete Institute in 2022.
Carbonate Binders: historic developments and Future Perspectivs
This paper reviews the historic developments and provide some future perspectives of carbonate binders. The first patent on the production of concrete products through carbonation was granted in 1870. Some detailed studies on the carbonation of hudrauliic and non-hydraulic calcium silicates were published in the earli 1970’s. However, quick carbonation curing of desired concrete products was not possible until pre-conditioning technology was invented in the middle of 2000’s. The products of fully carbonated unhydrated or hydrated calcium silicates are calcium carbonate and silicate. However, it is impossible for molded products to be carbonated completely in a short period of carbonation curing time, then calcium silicate hydrate with low C/S ratios can be detected. The addition of some calcium carbonated powder can increase the carbonation degree to certain extent. Calcite is the most identified calcium silicate, other forms of calcium carbonate such as aragonite and vaterite may also form depending on the raw materials and carbonation conditions. Magnesium salts can be added to regulate the formation of aragonite, which has needle morphology and results in higher flexural strength of the carbonated products. Magnesium oxide and magnesium silicate can also be effectively carbonated to produce construction products. However, magnesium is not widely available and usually too expensive for the production of carbonated construction products. Those industrial by-products or waste materials with a high calcium or magansium content such as high calcium fly ash, steel slag, magnesium slag, recycled concrete fines can be directly molded and carbonated to produce construction products. The urgent need is to identify or develop some additives to further increase the carbonation degree of carbonatable binders. The production of carbonated products through carbonation technology can use up to several hundred million tonnes of CO2.