a r t i c l e i n f o A hydration kinetics model for Portland cement is formulated based on thermodynamics of multiphase porous media. The mechanism of cement hydration is discussed based on literature review. The model is then developed considering the effects of chemical composition and fineness of cement, water–cement ratio, curing temperature and applied pressure. The ultimate degree of hyd...

This study evaluated the sealing ability of apical plugs made of white and gray MTA-Angelus and white Portland cement placed via the root canal and having different thicknesses (2, 5 and 7 mm). Ninety extracted human single-rooted teeth were instrumented using a size 40 K-file to standardize the foraminal opening by the stepback technique. The teeth were assigned to 3 groups (n=30), according t...

Concrete is one of the most widely used construction materials in the world. However, the production of portland cement, an essential constituent of concrete, leads to the release of significant amount of CO2, a greenhouse gas; one ton of portland cement clinker production is said to creates approximately one ton of CO2 and other greenhouse gases (GHGs). Environmental issues are playing an impo...

The aim of this study was to determine the effect of the exposure of different endodontic materials to different dye solutions by evaluating the optical density of the dye solutions. Seventy-five plastic tubes were filled with one of the following materials: AH Plus, Sealapex, Portland cement, MTA (Angelus and Pro Root) and fifteen control plastic tubes were not. Each specimen of material and c...

Radioactive waste generated during the reprocessing of fuel rods by the U.S. Department of Energy (DOE) is stored in underground tanks at Hanford, Savannah River and INEEL. The liquid fraction commonly referred to as sodium bearing waste (SBW), is a highly alkaline solution containing large amounts of sodium hydroxide, sodium nitrate and sodium nitrite. It has been shown that SBW can be mixed w...

In this paper, the effects of carbonation on pore structure of blended pozzolan cement pastes were investigated. Ordinary Portland cement OPC was partially replaced with ground palm oil fuel ash POA , ground rice husk ash RHA and classified fine fly ash FA . The strength, total porosity, specific surface area, and pore size distribution were tested. In general, incorporation of pozzolans increa...

Sustainability is important to the well-being of our planet, continued growth of a society, and human development. Concrete is one of the most widely used construction materials in the world. However, the production of portland cement, an essential constituent of concrete, leads to the release of significant amount of CO2, a greenhouse gas (GHG); production of one ton of portland cement produce...

The raw materials constituting the Portland cement are mainly lime, silica, alumina and iron oxide. During the manufacturing process, a glassy quasicrystalline clinker is formed which is ground, normally with addition of 1-3 wt% of CaSCU in the cement powder. This powder has four major constituents: 3 CaO"SiO2 (in cement chemists' notation C3S), 2 CaOSiO2 (C2S), 3 CaOAl2O3 (C3A) and 4 GaOAl2O3F...

Data on respiratory symptoms and pulmonary function were obtained for 2736 Portland cement plant workers and 755 controls. Personal dust samples contained a geometric mean concentration of 0.57 mg/m3 for respirable dust and 2.90 mg/m3 for total dust. Cement workers and controls had similar prevalences of symptoms, except that 5.4% of the cement workers had dyspnoea compared with 2.7% of the con...

Recyclable concrete pavement was made from fly ash and crushed limestone sand and gravel as aggregates so that the concrete pavement could be recycled to raw materials for cement production. With the aim to use as much fly ash as possible for the sustainable development of society, while achieving adequate strength development, pavement concrete having a cement-replacement ratio of 40% by mass ...