Characterization of scoria rock from Arabian lava fields as natural pozzolan for use in concrete

Abstract

The feasibility studies of using alternative cementitious materials (ACMs) in concrete construction are conducted using various characterization tests. Different samples of scoria rocks (SR) were procured from different regions of the Arabian Shield and investigated for use as ACMs. Various methods and characterization techniques were conducted. Characterization results revealed that the pozzolanic activity of SR in mortar does not correlate well with the sum of the main elemental oxides (SiO₂+Al₂O₃+Fe₂O₃), as per the requirement of ASTM C618. Concrete mixtures containing 30% SR per cement weight were prepared and tested at 28 and 90 days to evaluate the performance of SR for construction applications. Furthermore, the mortar and concrete mixtures containing SR have shown a slow rate of pozzolanic activity at early ages. However, the development in compressive strength was enhanced at later ages dependent on the mineralogical compositions of SR. It is concluded that the improvement in strength could be corroborated based on the formation of tobermorite-like structures, as confirmed using XRD and thermal analyses. These structures result from the reaction of minerals of amorphous sodium aluminosilicate phase (albite minerals) in SR with portlandite liberated during cement hydration. Conclusively, SR reacts as a pozzolan not as a filler.

Keywords:

• Scoria rocks
• natural pozzolan
• pozzolanic activity index
• microstructure
• tobermorite-like structure

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This Project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number 08-ENV 314-02.