Physical and chemical characteristics of ashes formed at burning oil shale at temperatures 500, 600, 700, 800, 900 and 1030 °C were studied. Standard procedures were used to determine both pozzolanic activity and binding parameters. The most suitable characteristics were provided with oil shale ash formed at 700 °C. Ashes (15 and 30%) were added to ordinary Portland cement. The optimum pozzolan...

It is difficult to obtain high quality samples of natural material covering a range of densities and degree of cementation, so study on the sample preparation techniques with similar mechanical properties of natural samples are very important. Experiments were carried out to study the effects of cementation of different materials on the mechanical properties of calcareous sand, e.g., the effect...

OBJECTIVE The purpose of this study was to investigate the pulpal response of dogs' teeth after pulpotomy and direct pulp protection with MTA Angelus, ProRoot, Portland cement and white Portland cement. STUDY DESIGN Seventy-six teeth were treated with these materials. One hundred twenty days after treatment, the animals were sacrificed and the specimens removed and prepared for histological a...

Portland cement has been analyzed and compared to mineral trioxide aggregate (MTA) because of their chemical similarity. The possibility of using this material as a less expensive alternative to MTA in dental practice should be considered. In view of this, the present study compared the components of a Portland cement (Votoran) to two commercial brands of MTA (Pro-Root and MTA-Angelus). Twelve ...

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...

The present study was done to assess cement dust exposure and its relationship to respiratory health effects, both acute and chronic respiratory symptoms and ventilatory function impairment among Portland cement factory workers in Khash located in the south part of Iran. A cross-sectional study was conducted at Khash Portland cement producing factory in Iran in 2001. A total of 170 exposed and ...

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...