# Clinker-Free Cement: A New Reality
## 1 Introduction  
Committed to mitigating environmental impacts, there is a growing search for alternative cement mixtures to Portland cement (PC), which offer compatible or superior performance to the binder. This is justified because the cement industry is responsible for both the large consumption of natural raw materials and the emission of gases, mainly CO\({}_{2}\), that contribute to the greenhouse effect and the emission of particulate matter [1, 2].  
Important studies seek supplementary cementitious materials (SCM) based on solid waste to partially replace Portland cement and to produce geopolymer or alkali-activated cement that uses solid waste as a substitute for natural raw materials [2, 3, 4].  
Granulated blast furnace slag (GBFS), a byproduct of pig iron production, is not only an important SCM widely used in the production of Portland cement due to its latent hydraulicity but is also studied in the search for alternative cement as an alkali-activated material. GBFS consists of a material rich in amorphous silica content and aluminum oxide, making them a potential cement alternative material [2].  
In terms of cement, supersulfated cement (SSC) stands out for its high-content use of blast furnace slag, which can vary between 70 and 90%, in addition to 10-20% calcium sulfate and up to 5% alkaline activator, for which alkaline hydroxides, clinker or PC can be used [5, 6].  
SSC is considered a low-carbon cement and environmentally friendly material with superior mechanical and durability performance compared to PC. The formation of ettrin-gite and C-S-H crystals during the hydration process confers SSC a higher late mechanical strength with a lower heat of hydration release, as well as superior chemical resistance, especially against sulfate attacks [2, 5, 6].  
However, it has qualities negatively associated with the use of Portland clinker as an alkaline activator for GBFS. The decomposition of blast furnace slag is achieved in a highalkalinity environment, which commonly occurs through the use of clinker or Portland cement, creating an economic and environmental disadvantage for the binder [5,6].  
Basic Oxygen Furnace (BOF) slag, a steelmaking waste generated during steel production, is rich in calcium oxide and hydroxide. It also has similar phases in its composition to that of Portland clinker, such as dicalcium and tricalcium silicates (Ca\({}_{2}\)SiO\({}_{4}\) and Ca\({}_{3}\)SiO\({}_{5}\)), in addition to tetracalcium ferroaluminate (Ca\({}_{4}\)Al\({}_{2}\)Fe\({}_{2}\)O\({}_{10}\)), providing hydraulicity to the slag, although less significantly compared to blast furnace slag and Portland clinker. These characteristics of BOF slag allow the residue to be a possible replacement for the alkaline activator for blast furnace slag in formulations such as SSC [7, 8, 9, 10].  
In this sense, this research proposed not only not using clinker in the production of cement, but also producing cement mixtures exclusively from industrial waste, composed of blast furnace slag and hydrated gypsum residue, as well as BOF slag as an alkaline activator of the mixtures, to evaluate the mechanical performance and durability of cement mixtures without clinker in comparison to those of PC and SSC.