Potential use of activated Algerian natural pozzolan powder as a cement replacement material

Abstract

The purpose of this experimental work is to develop a suitable approach for an alkali-activated binder material to replace cement CEM-II/42.5 by 80% of natural pozzolan. The chemical activity of silica and alumina found in Algeria's natural pozzolan is improved using heat treatment and chemical curing, together with several alkali activators, including a 6-mole NaOH and a 6-mole KOH along with CaCl₂, Na₂SO₄ and Na₂SiO₃. The chemical and morphological processes are monitored using X-ray diffraction, TGA and DTA, as well as particle size distribution analyses. Laboratory tests show that thermal pretreatment positively affects the compressive strength; moreover, the use of 6% Na₂SiO₃ and 6% Na₂SO₄ results in increased short-term and long-term compressive strength, respectively. Optimal compressive strength values are reached under chemical activation and thermal pretreatment processes. These combined processes also affect Young's modulus values and the relative deformations caused by ultimate stresses. This experimental work highlights the potential of natural pozzolan in producing an economical and environmentally-friendly sustainable material that can be substituted for Portland cements and used in multiple engineering applications.

Keywords:

• New approach
• chemical activation
• thermal curing
• compressive strength
• Young's modulus
• behavioural curves

Disclosure statement

No potential conflict of interest was reported by the authors.