Comparative analysis of biogenic and chemical sulfuric acid attack on hardened cement paste using laser ablation-ICP-MS

The aim of this study was to investigate the relative role of chemically and microbially derived sulfuric acid (H2SO4) corrosion on hardened cement paste representing a concrete binder. Cement stone disks were exposed to chemical H2SO4 (pH 1.0 and 2.0) and biological H2SO4 (pH 1.5–2.1). After 28 days, the degree of damage was evaluated by common visual-physical parameters and laser ablation-ICP-MS as a novel evaluation tool to assess changes in elemental distributions. The results revealed a pH-dependent degree of damage. The 4 mm thick disk at pH 1.0 was completely corroded. For the disks exposed to biogenic and chemical H2SO4 at pH 2.0 an intact core remained with a similar thickness of the corrosion layer (1.8–2.0 mm) and sulfuric acid penetration depth (1.1–1.3 mm). Since the elemental distribution was similar in the corroded layer independent of applying biological or chemical H2SO4, no obvious differences between the two acid attacks were revealed.