الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Aerated (cellular) concrete is basically composed of fine ground sand as the filler and cement (and/or lime) as the binder slurry that foamed by introducing air through it when a foaming affecting agent like Al powder used. In practice, the fine sand filler can be partially replaced by other siliceous materials as some industrial waste by-products.
The present study deals with the investigation of some factors which are believed to influence the quality of the low density (aerated) building units. Also, the effect of incorporation of some industrial waste by-products as to partially substitute equal amounts of the ground sand filler in the starting materials is also studied. The samples were prepared through either of two techniques: low temperature preparation or high pressure steam (autoclave) preparation.
To fulfill this aim, the main starting materials (ground sand, ordinary Portland cement, lime and aluminum powder) as well as the utilized industrial waste by-products (Homra, water-cooled slag, air-cooled slag and silica fume) were chemically analyzed using the XRF technique in addition to the wet chemical analysis. They were also characterized for some important physical and/or mechanical properties using the standard techniques.
For the low temperature preparations, the main starting materials were ordinary Portland cement and aluminum powder. The influence of Al powder content and of water / solid ratio on the physico-mechanical properties of the products were studied. Also, the substitution of various percents of fine ground sand, Homra, water-cooled slag and silica fume to replace equal amounts of ordinary Portland cement in the starting materials on the properties of the prepared samples was investigated.
For the samples prepared under high pressure steam curing, the relative proportions of the main starting materials on the physico-mechanical properties were firstly undertaken for the sake of optimization. This was followed by studying the influence of water/solid ratio and of Al powder content during the preparation of the slurry mix.
The effect of autoclaving conditions either pressure or period of hydrothermal treatment was carefully studied. Steam pressures of 10, 12 and 14 atmospheres (bars) for periods ranged between 2 hrs and up to 12 hrs were applied.
The influence of the storage conditions of the lime used for preparation of slurry mixes was also considered.
One of the main targets of this study is to investigate the influence of substitution of various percents of each of the following: waste clay-bricks (Homra), water-cooled slag, air-cooled slag, silica fume and ultra fine sand to replace equal amounts of the ground sand filler in the starting materials. For all the studied preparations, the products were investigated for their compressive strength and bulk density determinations. Their mineralogical compositions were studied by X-ray diffraction aided with differential thermal analysis techniques. The microstructural features of some selected samples were also investigated by scanning electron microscopic technique.