نتایج جستجو برای: cement
تعداد نتایج: 27770 فیلتر نتایج به سال:
The aim of this research was to study the effect of various water-to-cement ratio on the properties of pervious concrete. Tests were carried out to find the optimum water-to-cement ratio that gives a high compressive strength with acceptable permeability. The tests of fresh density, compressive strength at 7days, porosity and water permeability for four mixes of pervious concrete with various w...
The use of additives to improve the quality of cement grouts is crucial for civil engineering, especially in foundation construction. This article presents experimental data concerning the compressive strength, elastic modulus, bleeding and injectability of microfine cement grouts modified with epoxy and acrylic resin emulsions. Strength properties were obtained at different curing ages. For fu...
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...
The main problem with cement composites is that they have structural defects, including cracks, holes, and a disordered morphology, which significantly affects their strength and durability. Therefore, the construction of cement composites with defect-free structures and high strength and long durability is an important research topic. Here, by controlling the size and chemical groups of graphe...
The compatibility of wood from mountain pine beetle (Dendroctonus ponderosa) killed lodgepole pine (Pinus contorta var. latifolia) with Portland cement was investigated based on time-since-death as a quantitative estimator, and the presence of blue-stained sapwood, brown rot, or white rot as qualitative indicators. The exothermic behavior of cement hydration, maximum heat rate, time to reach th...
In this paper, two types of sustainable cementitious composites, geopolymer and magnesium phosphate cement, are introduced. The geopolymer is a type of amorphous alumino-silicate products and magnesium cement is MgO based cementitious material. Geopolymer can be synthesized by polycondensation reaction of geopolymeric precursor, and alkali polysilicates. The MgO cement can be obtained by proper...
Osteoporotic vertebral compression fractures (OVF) are an increasing public health problem. Cement augmentation (vertebroplasty of kyphoplasty) helps stabilize painful OVF refractory to medical treatment. This stabilization is thought to improve pain and functional outcome. Vertebroplasty consists of injecting cement into a fractured vertebra using a percutaneous transpedicular approach. Balloo...
Vertebral compression fracture is the most common complication of osteoporosis. It may result in persistent severe pain and limited mobility, and significantly impacts the quality of life. Vertebroplasty involves a percutaneous injection of bone cement into the collapsed vertebrae by fluorescent guide. The most commonly used bone cement in percutaneous vertebroplasty is based on the polymerizat...
Electromyography (EMG) of respiratory muscles is a reliable method of assessing the ventilatory muscle function, but still its use has not been fully utilized to determine the occupational and environmental hazards on respiratory muscles. Therefore, EMG of intercostal muscles was performed to determine the dose response effect of cement dust on respiratory muscles competence. Matched cross-sect...
OBJECTIVES The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. METHODS The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). ...
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