It is not enough that we build, rather, we must build to ensure that the structures withstand the test of time; this is the hallmark of sustainability, and our aim.
Ambuja Cement - Dr. Nadeem M. Head - Alccofine
Rapid urbanisation and fast-paced developments have led to increased usage of cement, which increases the carbon footprint and its adverse impact on sustainable construction. Currently, majority of the cement is being made with greater fineness and higher calcium silicate (C3S) and is prone to early cracking due to high thermal shrinkage and high amount of calcium hydroxide in the concrete matrix. This ultimately leads to leaching with more capillary pores and ultimately early deterioration.
Effective ways to reduce carbon footprint in concrete applications
In order to address these concerns, the construction industry initiated use of optimum cement content (Ordinary Portland cement) by replacing with pozzolanas (SCMs - Fly ash & GGBS which are industrial byproducts). The main disadvantages of using SCMs observed are reduction in early strength, early shrinkage cracks, more water demand, stiff mix, pumping issues etc. On the other hand, the requirements of modern-day high-performance concrete (HPC), precast concrete, high grade concrete, ultra-high performance concrete (UHPC) required high early strength along with stringent durability parameters which limits the use of OPC.
Sustainable, economic, durable concrete
Innovating for sustainable products is the centre of Ambuja Cements’ ethos. To produce sustainable, economic, and durable concrete, it becomes necessary to make low w/b ratio in concrete mix along with microfine SCMs to replace maximum quantity of OPC. Also, it has been observed that along with fineness, particle size distribution (PSD) has a profound influence on the ‘rheology’ of concrete. Well graded PSD, when combined with other cementitious materials, gives better strength and durability to concrete.
Plus, better the packing of the particle system, higher would be the strength of cement and concrete. The most important properties of a particle system is the packing density and improving the Interfacial Transition Zone (ITZ) by addition of microfine fine particles.
ALCCOFINE 1203, for instance, is a specially processed product based on slag of high glass content with high reactivity obtained through the process of controlled granulation. The raw materials are composed primary of low calcium silicates. The processing with other select ingredients results in controlled particle size distribution (PSD). Due to its unique chemistry and ultra fine particle size, it needs less water for a given workability. It can also be used as a high range water reducer to improve compressive strength or as a super workability aid to improve flow.The additives for concrete, which is Alccofine’s core portfolio, works by the “packing effect” or fills the pores between concrete surfaces, which reduces water’s ability to permeate such structures.
