Capillary porosity percolation in a hydrating cement paste has a large influence on transport properties and durability. Percolation can be examined using low-temperature calorimetry and using microstructure models. In this paper, the two approaches are compared for cement pastes with different water-to-cement ratios and exposed to various curing conditions. The influence of sealed curing is se...

Tensile bond strength and failure location were evaluated in vitro for three types of direct bonding cements (unfilled, low filled, and highly filled) with three types of brackets (polycarbonate, stainless steel, and ceramic) using natural teeth and plastic as substrates. An unfilled acrylic cement gave the highest values of bond strength for both the plastic and ceramic brackets, whereas a hig...

Abstract Calcined diatomaceous earth (CDE) with a maximum grain size of 143 ?m was used to partially replace 5 and 10% cement in ultra-high-performance concrete (UHPC) mixtures. The other materials producing the include Ordinary Portland Cement, iron ore powder, river sand sizes 112.5, 231, 766.2 ?m, respectively. Moreover, UHPC specimens designed water–cement ratio 0.2 superplasticizer 1.5% fr...

An oil and gas well cementing in Gachsaran formation, where sustained annular pressure has been reported in many wells, presents a big challenge in Maroon field. The main challenges are preventing gas migration and achieving zonal isolation using a competent cement sealant system which is able to withstand downhole stresses and high temperatures during production cycles. Unlike conventional cem...

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To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As) in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA) and X-ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO41...

This paper presents a fully differential dualended ultralow-voltage (ULV) FGUVMOS operational transconductance amplifier (FGUVMOS-OTA), and a Gm-C filter where the FGUVMOS-OTA is used. The OTA has no internal nodes, rail-to-rail operation and dynamic load. The cut-off frequency of the Gm-C filter is tunable over more than 5 decades. The circuits may be operated with supply voltages down to 200mV.

The attachment of an implant material to bone relates to surface roughness and surface chemistry. There is a relatively low chemical bonding strength of so-called bioactive surfaces. Hydroxyapatite interfaces typically have an interfacial tensile strength of 0.15-1.5 MPa. An attachment force similar to that of bioactive surfaces might also be reached through mechanical interlock with ordinary b...