Most existing test methods determine the sulfate resistance of concrete using accelerated methods in the laboratory, on mortar or concrete specimens. However, these accelerated tests often use high sulfate concentrations or require very complicated setups, which may alter the deterioration mechanisms, while still being laborious and time-consuming. Additionally, the need for more sustainable binders and distinctive properties of systems incorporating emerging supplementary cementitious materials (SCMs) may limit the applicability of conventional test methods. In this context, the Working Group 3 of RILEM TC 298-EBD aims to develop simple accelerated test methods on cement pastes for evaluating sulfate resistance, which directly investigate the reactive component of concrete. Working at this scale can provide reliable results in a much shorter time than traditional tests on mortars and concretes, while providing means to assess the impact of different SCMs and binders on the resistance to sulfate attack. This paper presents our first step, a critical literature review on sulfate deterioration testing from the concrete/mortar to the cement paste scale. We present a general introduction to sulfate attack, common test parameters, assessment methods, test setups for paste specimens, a discussion of potential approaches, and concluding remarks. Insights gained from this review will be instrumental in establishing an effective and reliable approach to sulfate deterioration testing on cement paste specimens.

In this review by TC- 282 CCL, a comprehensive examination of various facets of chloride ingress in calcined clay-based concrete in aggressive chloride-rich environments is presented due to its significance in making reinforced concrete structures susceptible to chloride-induced corrosion damages. The review presents a summary of available literature focusing on materials characteristics influencing the chloride resistance of calcined clay-based concrete, such as different clay purity, kaolinite content and other clay minerals, underscoring the significance of pore refinement, pore solution composition, and chloride binding mechanisms. Further, the studies dealing with the performance at the concrete scale, with a particular emphasis on transport properties, curing methods, and mix design, are highlighted. Benchmarking calcined clay mixes with fly ash or slag-based concrete mixes that are widely used in aggressive chloride conditions instead of OPC is recommended. Such comparison could extend the usage of calcined clay as a performance-enhancing mineral admixture in the form of calcined clay or LC2 (limestone-calcined clay). The chloride diffusion coefficient in calcined clay concrete is reported to be significantly lower (about 5–10 times in most literature available so far) compared to OPC, and even lower compared to fly ash and slag-based concrete at early curing ages reported across recent literature made with different types of cements and concrete mixes. Limited studies dealing with reinforcement corrosion point out that calcined clay delays corrosion initiation and reduces corrosion rates despite the reduction in critical chloride threshold. Most of these results on corrosion performance are mainly from laboratory studies and warrant field evaluation in future. Finally, two case studies demonstrating the application of calcined clay-based concrete in real-world marine exposure conditions are discussed to showcase the promising potential of employing low-purity calcined clay-based concrete for reducing carbon footprint and improving durability performance in chloride exposure.