Effects of sulfuric acid attack on hydrated calcined clay–limestone cement mortars

Abstract

The paper presents experimental findings on the performance of Limestone Calcined Clay Cement (LC3) in acidic media. LC3 was made by inter-grinding a blend of 50 % clinker with ground 30 % Fired Rejected Clay Bricks (FRCB), 15 % limestone and 5 % gypsum. Compressive strength and water absorptivity of LC3 mortars were investigated vis-à-vis commercial Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC). Microstructural analysis of hydrated LC3 samples was conducted using Scanning Electron Microscope (SEM) before and after immersion in 3% H2SO4. LC3 reported the least water absorptivity than PPC and OPC. Additionally, LC3 exhibited equivalent water absorptivity and resistance to acid attack compared to PPC. Micro-cracks were observed in SEM images from LC3 samples after immersion in acid. In conclusion, strength loss, at w/c = 0.50 and 0.60, LC3 exhibited 12.71 % and 14.06 % respectively, higher resistance to acid attack than OPC.

Keywords:

• acid resistivity
• blended cement
• fired rejected clay bricks
• compressive strength
• porosity

Acknowledgment

The author wishes to sincerely thank the Department of Materials Testing under the Ministry of Roads in Kenya and East Africa Portland Cement Company for providing the laboratory facilities used in this research.

Disclosure statement

The author declares that there are no conflicts of interest.

Additional information

Funding

This research was financially supported by the Meru University of Science & Technology 5th Internal Research Call fund.