State of the art review on Supplementary Cementitious Materials in India – I: An overview of legal perspective, governing organizations, and development patterns

Highlights

• SCM – overview, environmental befits and application challenges in India.

• Legal perspective (standards, directives & guidelines) for SCM utilization in India.

• Overview of organizations with significant impact on SCM utilization in India.

• Analysis of development of SCM use as a sustainable construction practice in India.

• Solutions promoting use of SCMs as clean technology in Indian Construction Industry.

Abstract

Growing concern over the environment has led the Indian Construction Industry towards Sustainable Development and Circular Economy. As a part of the solution, a part of clinker, the primary constituent of cement, is replaced by industrial by-product, waste ash, or similar fine materials, collectively known as Supplementary Cementitious Materials or SCM. Several organizations are actively engaged towards development, dissemination and promotion of technologies on SCM utilization. In Indian construction industry utilization of SCM is contingent on the existing legal framework, which includes relevant directives, standards, and technical guidelines. Literature shows directives have the highest influence followed by standards on the utilization of SCMs. Although provisions exist for utilization of SCMs in the absence of a relevant standard, they are rarely utilized. This makes knowledge of existing legal framework imperative for integrating studies on SCM utilization with industrial practices and subsequent development in the legal framework. The manuscript provides a state of the art review on existing legal policies, organizations influencing SCM utilization and an overview of development pattern. The manuscript will serve as a support tool for industry professionals, at the time of industrial application of SCM, and as an outline for the research community, for analysis of legal barriers. The manuscript will promote the utilization of SCM in the Indian construction industry through a better understanding of legal barriers.

Introduction

Environmental change has been globally recognised as a serious threat and nations are moving towards the reduction of greenhouse gas emission (United Nations, 2015). Under the United Nations Framework for Climate Change, 185 parties, including India, have agreed on the Paris agreement towards the realization of this goal (United Nations, 2015). India has taken the approach of waste to wealth as a part of its sustainable practices for its contribution towards climate justice (NDC India, 2019). In India, the construction sector is expected to go from being the second-largest consumer of materials in 2007 to the largest resource-consuming sector before 2020 (GIZ, 2016). This makes the application of sustainable practices in the Indian construction sector significantly important.

Indian construction sector is experiencing exponential growth and it is estimated that 70% of buildings that will exist in 2030 are yet to be built (GIZ, 2016). To feed the construction growth, massive quantities of cement have been consumed by the construction industry. With an annual consumption of 296 $\times {10}^6$ t and production of 297.56 $\times {10}^6$ t, India was the second-largest producer and consumer of cement in 2018 (IBEF, 2019). This rate of consumption for cement becomes alarming when environmental impacts associated with cement manufacturing are taken into consideration.

Cement manufacturing globally is responsible for 7% of total carbon emission, with Indian cement industry accounting for 588 kgCO₂/t of cement for 2017 (WBCSD, 2018). Cement manufacturing is also facing challenges of high energy requirement (IEA, 2018), and criticality of limestone in terms of sustainability (GIZ, 2016). NITI Aayog (2017) suggests efficient resource utilization through the use of secondary materials for sustainable development of the Indian construction industry. One such practice is the reduction of clinker to cement ratio, i.e. clinker factor (IEA, 2018).

Clinker is the intermediate product of cement manufacturing, which is blended with other materials before being utilized as cement. One can appreciate the effect of low clinker factor in recent studies for sustainable development, like composite cement (IS 16415, 2015) with clinker factor between 0.35 and 0.65 requires 57% less raw material, 52% less thermal energy, 34% less electrical energy, and 56% less CO₂ emissions (WBCSD, 2018). Technical studies have shown that incorporating different materials by blending with clinker in cement can effectively lower clinker ratio (CSI, 2013). These materials are termed as Supplementary Cementitious Materials or SCM.

It is estimated, a reduction of clinker factor from 0.65 to 0.60 in the global cement industry can reduce 2.9 $\times {10}^9$ t of CO₂ or almost 35% of current annual industrial direct CO₂ global emissions (IEA, 2018). India, with clinker factor of 0.72, in 2014, has a significant potential of clinker factor reduction (IEA, 2018). On account of associated environmental benefits, SCM utilization can be considered a crucial step towards sustainable growth in the construction industry.

Many of the SCMs are otherwise classified as waste; among these, some pose a critical threat to the environment. Fly ash, a form of SCM, is a fine waste resulting from the combustion of pulverized coal (IS 3812: Part 1, 2013). Disposal of fly ash in the open environment results in the deterioration of soil as well as groundwater (Khan and Umar, 2018). Fly ash particles can also spread through air disturbances and pose a serious risk to health (Wu et al., 2016). Environmental risks are not limited to fly ash; several of the wastes when left unchecked in the environment result in grave consequences. Marble wastes if not recycled for other industrial applications, will cause environmental pollution, including groundwater contamination (Tugrul, 2019). Effect on human health and other environmental concerns, were highlighted in a similar study on dimensional stone waste in India (Rana et al., 2016). Similarly, weathering action on the slags, wastes originating from the metal industry, have a negative impact on the environment (Piatak et al., 2015). Other than this waste disposal occupies land space, which itself becomes scarce against the growing volume of wastes.

In view of the environmental concerns, various techniques can be observed in the literature for safe disposal of waste by utilizing it in the construction industry. Conventionally, powder sized wastes with pozzolanic properties, like fly ash, have been used as a replacement to cement (Demir et al., 2019); and, coarse and fine-sized wastes, like waste marble, have been used as a replacement to aggregates (Tunc and Alyamac, 2018). Recent literature shows many more applications of waste in the construction industry. Fly ash can be utilized as environment-friendly cold bonded lightweight aggregates (Narattha and Chaipanich, 2018) and waste marbles can be used for developing aesthetic or architectural concretes due to their physical characteristics (Alyamac and Tugrul, 2014). Similarly, Lithium slag can be used as alkali-activated binders (Liu et al., 2019), and fly ash and GGBS can be used to make ambient cured one-part geopolymers, an eco-friendly technically viable alternative to conventional cement (Oderji et al., 2019).

Among several methods of waste utilization in the construction industry, the scope of this article has been limited to waste utilization as SCMs, on account of the two-fold advantages to the environment, i.e., clinker reduction and waste disposal.

Several studies have been conducted by researchers for exploring the potential of different waste materials as SCMs in the construction industry. Due to the sheer volume of literature, several comprehensive reviews have been done by researchers with an attempt of dissipating knowledge and promoting the use of SCMs. Table 1 provides a list of comprehensive reviews that have been carried out in the last decade, along with the nature of work carried out.

It can be seen from Table 1, that very few articles have covered the application scenarios of SCMs in the industry, compared to the articles discussing the technical evaluation of SCMs. The articles assessing the applicability of SCM in the construction industry have laid a strong emphasis on the barriers resulting from legal policies and regulations.

Lack of relevant standards and legal policies can act as barriers, limiting the use of technical studies in the construction industry, as highlighted in Fig. 1. Similar inferences, on the significance of legal barriers, have been made by several authors in the literature. Scrivener et al. (2018) identified the lack of suitable standards as a barrier for commercial production of LC3 at optimal composition. John et al. (2018), in reference to the use of limestone filler, highlighted the needs of standardization for increased limestone utilization. John et al. (2019), suggested the use of performance-based standards to improve SCM utilization. Martirena and Monzo (2018) highlighted the importance of Indian Standard, IS 4098, 1983, towards agricultural waste ash utilization. Hemalatha and Ramaswamy (2017) discussed the limitation of ASTM C-618-8a, 2009 and IS 1489: Part 1, 1991, and suggested a need for improvement in standards for a higher degree of incorporation of fly ash. Similarly, Juenger et al. (2019) concluded that with the growing developments in the utilization of SCM, improvement is required in existing standards.

Difference in formulation and implementation of legal policies can be observed despite similar environmental needs. On comparing the standardization process of fly ash, it is found that India initiated its fly ash mission in 1994 (CEA, 2018) which has now become a part of accepted guidelines. In contrast, countries like Vietnam issued the guideline for promoting the use of fly ash as late as 2014 (The Socialist Republic of Vietnam, 2014). John et al. (2018), observed the influence of raw materials on standard of different countries and reported that in the case of limestone, despite successful high filler industrial application of up to 35%, in European countries, India standards have a significantly lower permissible limit of 5%. This highlights the fact that the environmental benefits of SCM utilization are not always sufficient for the modifications in the legal framework.

Analysis of legal policies in India (Section 3.2), indicate alternate provisions for utilizing SCMs in the Indian construction industry. The existing literature does not mention these alternate provisions; this leads to the conclusion that information on legal policies and guidelines are not well disseminated.

As evident from the discussion, SCM utilization is a necessity for both the environment and sustainable growth of the construction industry. Despite active efforts of the research community towards realizing this goal, the application of SCM in the Indian construction industry has been limited by legal barriers. This makes understanding and practice of legal policies crucial for the sustainable growth of the construction industry. To promote SCM utilization through a better understanding of legal barriers, authors felt motivated to attempt this study by presenting a state of the art review on the legal perspective, governing organizations and development patterns, on the use of SCM in the Indian construction industry.

Unlike other comprehensive reviews on SCMs, work in this paper is intended to provide a comprehensive review of the legal framework governing the use of different types of SCMs in India. This paper also discusses important organizations, the nature of work carried out by them and thrust areas of their research, so that the efforts towards sustainable growth can be collaborated with the concerned organizations. Additionally, development patterns have been analysed to understand the effect of the legal framework on the utilization of SCMs in the Indian construction industry.

For better understanding, the manuscript can be broken down in four segments. The first segment of the manuscript highlights the significance of the study of the legal framework for improving SCM utilization in the Indian construction industry, followed by the second segment of discussion on the procedure adopted for identifying key literature and its analysis. The third segment reports the key observations from various selected literature, followed by the fourth segment of concluding remarks. The authors believe that this article will help to bridge the gap between technical studies and industrial application.