Durability of concrete — Degradation phenomena involving detrimental chemical reactions

Pulverized Fuel Ash Introduction Classification Physical Characteristics Chemical and Mineralogical Composition Characteristics of PFA Produced in Fluidized Bed Combustion Process Characteristics of PFA Produced after Co-Combustion of Bituminous Coal and Petcoke Leaching Characteristics Radioactivity, Toxicity, and Occupational Health Processing for Quality Improvement and Assurance Processing of Unusable PFA Quality Control Addition of PFA to Cement and Concrete Summary Blast Furnace Slag Introduction Granulation of BFS Ground Granulated Blast Furnace Slag Chemical and Mineralogical Composition of Cementitious BFS Quality Control Addition of BFS and GGBS to Cement and Concrete Quantitative Determination of Blast Furnace Slag in Cement Summary Silica Fume Introduction Types of Silica Fume Physical Characteristics Chemical and Mineralogical Composition Toxicity and Occupational Health Quality Control Addition of SF to Cement and Concrete Summary Rice Husk Ash Introduction Relevance of RHA for the Sustainability of Construction Industry Rice Husk Production Physical and Chemical Characteristics Addition of RHA to Cement and Concrete Summary Metakaolin Introduction Production Physical and Chemical Characteristics Quality Control Addition of Metakaolin to Cement and Concrete Summary Hydration Introduction Progress of Hydration with Time (Hydration Periods) Reactants in Hydration Process Voids in Hydrated Cement Paste Interrelation of the Hydration Properties of Cement and Concrete Properties of Concrete during Early Stages of Hydration Hydration Reactions and Changes in Early-Age Concrete Properties Summary Strength and Durability Introduction Designing Structures for Strength and Durability Concrete Strength Mechanisms, Models, Standards, and Mitigation of Concrete Deterioration Durability Indices for Performance Based Design of Structures Sustainable Cement and Concrete Summary New Mineral Admixtures Introduction Biomass Combustion Ash Calcined Wastepaper Sludge Electric-Arc Furnace Dust Sewage Sludge Ash Municipal Solid Waste Ash Summary References Index

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Mineral Admixtures in Cement and Concrete

Durability of shotcrete for underground support– Review and update

A theoretical analysis of the detrimental influence of weak sodium sulfate solutions (Na2SO4) on the durability of concrete is presented. It was conducted using a numerical model that takes into account the coupled transport of ions and liquid and the chemical equilibrium of solid phases within the (partially) saturated system. Numerous simulations were performed to investigate the influence of various parameters such as water/cement (w/c) ratio (0.45, 0.65 and 0.75), type of cement (CSA Type 10 and Type 50), sulfate concentration (0–30 mmol/l of SO4) and the gradient in relative humidity across the material. All input data related to the properties of concrete were obtained by testing well-cured laboratory mixtures. Numerical results indicate that exposure to weak sulfate solutions can result in a significant reorganization of the microstructure of concrete. The penetration of sulfate ions into the material is not only at the origin of the precipitation of sulfate-bearing phases (such as ettringite and eventually gypsum) but also results in calcium hydroxide dissolution and C–S–H decalcification. Data also clearly emphasize the fact that w/c ratio remains the key parameter that controls the durability of concrete to sulfate attack.

Theoretical analysis of the effect of weak sodium sulfate solutions on the durability of concrete

The leaching of cement-based materials in aggressive water is studied according to several protocols of accelerated or non-accelerated tests. The paper analyses international experimental published data on leaching concerned with several parameters, like material parameters as water-to-binder ratio and silica fume content, and environmental parameters, like pH and temperature. Then, a simplified model based on this analysis is developed to predict the kinetics of leaching. This model assumes that the rate of leaching follows a square root of time. Each parameter is introduced as a weight function. Particularly, the paper introduces the coupling between the built database and the model.

Akira Deguchi

Papers

Leaching tests on different mortars using accelerated electrochemical method