The Effect of the Partial Replacement of Cement by Industrial Pozzolana on the Concrete Properties (Review Paper)

Abstract

Pozzolana (volcanic slag) is a substance used to make cement and is extracted from the mountains. It is of two types: natural, renewable pozzolana resulting from volcanic ash, industrial pozzolana resulting from recycling factory waste such as FLY ASH, coal ash resulting from the waste of burning coal for electricity production stations, and from iron slag resulting from Slag Blast Furnace Ground

Through previous studies, many results have been reached that can be summarized as follows:

Replacing cement with fly ash in large quantities (more than 30%) leads to an increase in compressive strength over time, with FA showing the highest strength at 90 days, and to an increase in the chloride resistance of concrete, especially when used with silica fume. Fly ash and silica particles improve the mechanical properties of concrete when used together to replace cement. Silica fume (SF) increases the early strength of concrete when used with fly ash (FA), which improves long-term strength. The triple mixture of cement (PC), silica fume (SF) and fly ash (FA) provides the highest compressive strength at all ages. Replacing silica fume with 5% of the cement content increases the compressive strength of concrete by 17-28% depending on the age of curing. Silica improves density and reduces the porosity of concrete due to smaller particle size, resulting in higher strength. However, silica fume Silica reduces the workability of concrete due to its high surface area. Rice husk ash (RHA) can be used together with biochar or superplasticizers to improve the mechanical properties and permeability as well as the strength of concrete exposed to high temperatures. Replacing 10-15% of cement with glass powder greatly improves the performance and strength of concrete. Glass powder releases alkaline ions that maintain a high pH in the pores and increase the reaction rates of other pozzolanics such as silica fume. Replacing 15% of cement with blast furnace slag can increase the compressive strength and sulfate resistance of concrete, especially at later ages due to its pozzolanic reaction. Higher replacement levels of blast furnace slag (>30%) are also beneficial for durability in a sulphate environment. Metaqualene (MK) promotes early and long-term strength development more than SF, replacing MK by 5% with other materials improves the properties compared to the normal reference. Materials like RHA, SF, FA, MK and ISSA (Incinerator Sewage Sludge Ash) show high pozzolanic activity in tests like slurry strip test and strength activity index test which indicates their reactivity.