The use of cement and concrete to immobilise radioactive waste is complicated by the wideranging nature of inorganic cementing agents available as well as the range of service environments in which cement is used and the different functions expected of cement. For example, Portland cement based concretes are widely used as structural materials for construction of vaults and tunnels. These const...

The setting and development of strength of Portland cement concrete depends upon the reaction of water with various phases in the Portland cement. Nuclear resonance reaction analysis (NRRA) involving the (1)H((15)N,alpha,gamma)(12)C reaction has been applied to measure the hydrogen depth profile in the few 100 nm thick surface layer that controls the early stage of the reaction. Specific topics...

synopsis-in this research, possible usage of eaf dust on cement is investigated. therefore, effects of addition of different percentages of eaf dust on the most important properties of cement such as hydration heat, water coefficient, viscosity, initial and final setting times, strength development and leachability of heavy metals were studied. results showed that eaf dust alters the characteri...

A solidification/stabilisation (S/S) process of washed municipal incinerator fly ash with Portland cement was used to manufacture solidified products with high ash content (55 and 70 wt.% of solids) and good performance characteristics in terms of setting, dimensional stability, compressive strength, and environmental quality. The S/S product containing 70 wt.% fly ash aged for 180 days at 20°C...

At present, sustainability is of major importance in the cement industry, and the use of additions such as silica fume as clinker replacement contributes towards that goal. Special foundations, and particularly micropiles, are one of the most suitable areas for the use of sustainable cements. The aim of this research is to analyse the effects in the very long-term (for 600 days) produced by sul...

7 We propose a new method to estimate the initial cement content, water content and free water/cement ratio (w/c) 8 of hardened cement-based materials made with Portland cements that have unknown mixture proportions and 9 degree of hydration. This method first quantifies the composition of the hardened cement paste, i.e. the 10 volumetric fractions of capillary pores, hydration products and unr...

Using the agar diffusion method, we conducted an in vitro study to evaluate the antimicrobial activity of mineral trioxide aggregate (MTA), new endodontic cement (NEC) and Portland cement at different concentrations against five different microorganisms. A base layer was made using Muller-Hinton agar for Escherichia coli (ATCC 10538) and Candida (ATCC 10231). For Actinomyces viscosus (ATCC 1598...

Dental materials based on Portland cement, which is used in the construction industry have gained popularity for clinical use due to their hydraulic properties, the interaction with tooth tissue and their antimicrobial properties. The antimicrobial properties are optimal in vitro. However in clinical use contact with blood may affect the antimicrobial properties. This study aims to assess wheth...

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a referen...

During the hydration of cement, tricalcium aluminate (C3A) reacts with gypsum and forms ettringite (AFt). Once all gypsum is consumed, ettringite can further react with remaining C3A and form monosulfate (AFm) at 1–2 days. Normally, at early ages, ettringite all transfers to AFm phase. After several months or years, ettringite can form again if a new source of sulfate becomes available in the p...