**4. Conclusions**

The emphasis on utilizing non-traditional SCM is gaining momentum; this is mainly due to the implementation of low-carbon footprint materials by many governments, non-governmental agencies, cement manufacturers and construction industries. The significance on the implementation of sustainable development goals (SDG) as stipulated by the United Nations in achieving multiple attributes of sustainable development, is fueled by the vast availability of industrial by-products, pollution and the release of huge amount of carbon dioxide.

Thus, the topic summarized in this chapter on the non-traditional SCM is vital. The oxide compositions of the SCM of RHA, POFA, POCP and EPP point to a comparison with conventional OPC and the other established SCM, such as fly ash, silica fume, ground granulated blast furnace slag and metakaolin. Though the particle shapes vary, and some are porous in nature, the replacement of 10–20% of the conventional OPC and other traditional materials to move forward towards the sustainable development is the need of the hour. Another important consideration is the future availability of fly ash, which has been a trademark product in blended cement. Due to the implementation of cleaner energy and to achieve the climate change targets, many governments committed to a longer-term plan by closing most of their coal-fired power plants. This will necessitate the cement manufacturers to look forward to other non-traditional materials as a replacement for fly ash.

The other factors such as filler effect, strength development, refinement of pores and the enhancement of the durability properties assume a great significance. It is well established that the addition of SCM in concrete impacts the strength development. This depends on the SCM characteristics such as fineness, shape and their pozzolanic properties. The quantity of the SCM added in the concrete also defines the outcomes. It is also established that the use of SCM as an additional material would enhance the strength and durability. Furthermore, the secondary hydration responses also benefit to the strength development, as well as the fact that the water-to-binder ratio is efficiently reduced. However, based on cement replacement, the early age strength tends to be adversely affected. This is dependent on the replacement level and reactivity of the SCM used.
