Cement, Energy and Environment

1 Transition to Low Carbon Cement-Based Construction Imperatives and Obstacles Anjan K Chatterjee Former Whole-time Director of ACC Limited, Mumbai and Chairman of Conmat Technologies Private Limited, Kolkata PREAMBLE Construction sector, an important component of the national economy, is large, multi-dimensional and predominant user of natural resources and energy. It is also responsible for emission of a large quantity of carbon dioxide, as it is dependent on materials like cement, steel, glass, polymers, etc. It is imperative that the cement-based construction activity makes a quick transition to low-carbon footprint. The objective is undisputed but the road map is not fully prepared. This article, based on the guest lecture delivered by the author at the celebration of ‘Cement Day’ by Indian Concrete Institute and ACC Ltd in November 2017 at Nagpur, is an attempt to trace the present movement of the sector towards low-carbon economy with its imperatives and obstacles. INTRODUCTION Construction occupies a pre-eminent position in the economy of all nations – more so in the fast developing country like India. The economic dimension of the construction sector in our country is large with Gross Value Addition (GVA) of 7.74 % within the industry contribution of 29.02% to Gross Domestic Product GDP), which is estimated at about 2.5 trillion US Dollars at nominal basis and 9.5 trillion at purchasing power parity basis in 2017. The GVA of the construction activity is in addition to the GVA of 16.57% contributed by the manufacturing sector that includes major building materials like cement, steel, glass and chemicals and another 2.25% from mining and quarrying that form an indispensable part of the manufacturing. The environmental impact of the built structures and construction activity is as large as its economic dimension. Globally speaking, the construction activity consumes about 40% of the world resources and also the same quantum of energy, emits 40% of CO 2 , and generates about the same proportion of wastes (now classified as ‘construction & demolition’ waste). Under the above circumstances, it is important that we move towards low-carbon cement and concrete industry and the related construction activity as early as possible, if we are concerned about minimizing the adverse impact of climate change emanating from CO 2 emission on our society and living. It is certainly not a debatable proposition but in all probability, the road map, fraught with frailties, is still in the process of evolving. The present article is an attempt to review how we have fared and what the drivers and barriers are in moving ahead. CONSTRUCTION DOMAINS AND THE BUILDING MATERIALS BASE We see the built structures all around us as we live, travel, work and relax in this environment. The entire infrastructure and super structure in the built environment tentatively cover the following construction domains:  Marine structures including ports and harbour  Hydro-electric structures including dams  Sewers and sewer treatment facilities  Industrial and chemical plants  Water conduits and storage facilities  Miscellaneous liquid-containing structures  Bridges, culverts, roads and motorways  Residential low- and high-rise buildings  Farmhouses and agro-industrial structures. Each of the above construction domains differs from the other in environmental exposure conditions and, therefore, in design and materials requirements. At the same time, the above nine domains indicate the enormously large span of construction activity, which, interestingly, is supported by cement and steel as the primary construction materials. The growth in production of cement and steel over the past sixty five years have been compared in Fig.1 along with the growth of population during the same period. The world cement production has grown three times that of crude steel. The dimension of the cement-based industry can be summarised as follows:  The world production of cement is the largest among the man-made materials.  The total production of all types of cement in 2016 was 4,2 billion tonnes