Emerging Alternative Cements for Construction Industry

Avanish Singh, M.tech, Maulana Azad National Institute of Technology, Bhopal
Kanchan Kushwaha, M.Tech, Samrat Ashok Technological Institute, Vidisha
Dr. Rakesh Kumar, Head & Senior Principal Scientist, Rigid Pavement Division, CSIR-CRRI, New Delhi

Introduction

Ordinary Portland Cement (OPC) has been ruling the cement-based construction industry since 18th century i.e. start of its commercial production. In last two decades, the manufacturing rate has grown from 1.5 billion metric tonnes in 2000 to over 4 billion metric tonnes in 2018 [1]. Global cement production is expected to increase from 4 billion metric tonnes in 2018 to 4.83 billion metric tonnes by 2030. Figure 1 shows the global production of OPC over last 8 years. Ordinary Portland cement (OPC) has stabilized itself as an essential and tactical commodity material [2]. Because of reliance on OPC, its global cement production has now reached to over 4 billion tonnes per year due to fast infrastructural development in emerging economies [3]. Approximately, 50% of world’s OPC is consumed to produce over 11 billion tonnes of concrete annually, while rest 50% is used for other applications such as mortars, screeds, coatings etc [4]. Today sustainable, economical and durable concrete is more desirable with increasing infrastructure and building demands [5]. As per an estimate, the global demand of cement is expected to increase over 12-15% by 2050 [6]. In past few years Middle East regions, Northern Africa and developing countries such as China and India have seen enormous growth. Presently, China is leading the cement industry by manufacturing 58% of the total global demand [3]. U.S. Geological Survey estimates that over 4 billion tonnes of cement produced annually and approximately 0.9 tonne of CO₂ is released per one tonne of cement produced as shown in figure 2 [3,7]. As per this estimation over 3.5 billion tonnes of CO₂ annually is being produced by the cement industry. Therefore, cement industry is responsible for nearly 5–7% of global CO₂ emissions [8]. Besides releasing CO₂ from cement plants, SO₂ (sulfur dioxide), NOx (nitrous oxides) are also being thrown in to atmosphere causing acid rain and greenhouse effect [9]. Excluding these gas emissions, cement manufacturing also roots to the depletion of natural resources. It is accepted that around 1.5 tonnes of raw materials is required to manufacture 1 tonne of OPC [10,11]. Furthermore, manufacturing of clinkers encompasses gigantic energy [12]. Hence, cement industry is facing massive challenges such as conservation of natural resources, escalating costs of energy sources, CO₂ emission reduction etc, with the current growing global demand [13,14].