Concrete, mortar and grout as far as I know in Vietnam

 In the past, it was common to see houses with walls built up with mud and chopped straw - a simple primitive mortar. When this material dry, it can stand medium rains but I don't think it's possible in heavy rains and storms. It's just a physical mixture.

Then people used to use ashes from wood, coal, or even mud, sometimes added with clay and sand but the most important material is lime. The alkaline environment created by lime allows hydration reactions to happen. As as result, the mixture become hard and has better strength though the setting times is quite slow - up to several days.

It's was not until the 19 century that modern cement was produced. The first cement factory was built in Vietnam in 1899. 

Limestone, clay, iron ore, bauxite, sand are baked at a temperature of about 1450 degree to form clinker, then clinker is ground to become cement powder. People also add gypsum, limestone, pozzolan etc. as additives.

Mortar is simply a combination of cement and sand. Grout is also mixed from cement and sand but added small-sized aggregate while aggregate of lager size is used in concrete.

Now with the development of steel-making, a great quantity of slag is discharged. Because the most common technology of iron-making is blast furnace. Let's talk about blast furnace slag, especially granulated blast furnace slag.

In the furnace, the molten iron is heavier than the slag so the slag floats above and flow in a different way. Cold water is sprayed to molten slag (prox. 1400 degree) and it is immediately cool down and broken into small particles (less than 5mm in size) with hardly any crystallization. Iron slag mainly consists of Ca, Si, Al, Mg. Clinker can be added with iron slag when being ground to produce cement or iron slag itself can be ground and then added to concrete, mortar and grout. In Vietnam, we can substitute up to 30% cement with ground granulated blast furnace slag. An estimated of 300kgs iron slag is discharged for every ton of iron.

Steel-making also discharge steel slag.  An estimated of 200kgs steel slag is discharged for every ton of steel. Steel slag is also used in cement manufacturing. Because of high content of Fe, it is used to substitute iron ore when producing clinker.

Using iron and steel slag in producing cement is a good way to deal with waste, protect the environment and save the natural resources.

Quangngai, November, 25th, 2022