Effects of pozzolan incorporation and curing conditions on strength and water resistance of natural gypsum pastes

Cengiz, Okan
There are large reserves of gypsum rock (CaSO4·2H2O) in Turkey and in various regions of the world. Heating gypsum rock to 140 - 190 0C causes it to lose three-fourths of its water molecules and turn into gypsum, called plaster of Paris; heat application over 190 0C results in loss of all the water molecules and this form of the material is called gypsum anhydrite. When gypsum is mixed with water, it gains cementitious property and hardens in a short time. Therefore, natural gypsum anhydrite and especially plaster of Paris are widely used in the construction industry. On the other hand, its not being water resistant and having low strength restrict the use of gypsum products for outdoor applications. In this study, the effects of pozzolan incorporation to natural gypsum pastes and application of various curing regimes for improving their water resistance and strength were investigated. Compressive strength and absorption tests on one thousand one hundred twenty two 5-cm cube specimens produced from v 13 different mixture types were conducted. Also the microstructures of these products were investigated using the analytical technique X-Ray Diffraction. The test results showed that water resistance and strength properties of pozzolan-incorporated gypsum products were improved. Curing of the product at elevated temperature regimes was an additional factor that contributed to this improvement. It was concluded that the natural gypsum mixtures prepared and cured at the above-mentioned conditions could also be used for outdoor applications.


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Erdoğan, Sinan Turhan (American Society of Civil Engineers (ASCE), 2015-07-01)
Perlite is a volcanic aluminosilicate abundant in several countries that are major producers of portland cement. The amorphous nature and silica-to-alumina ratio of ground perlite indicate that it can be activated with alkaline solutions. This study presents the strength development of mixtures containing only ground perlite as their powder binder, activated with sodium hydroxide and/or sodium silicate solutions, at room temperature or using oven curing. The structure of the formed geopolymers is investigat...
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Rainfall triggered landslides are one of the most common natural hazards in many countries throughout the world, as well as in Turkey. This study investigates the effect of unsaturated soil properties on landslide-triggering rainfall intensity-duration threshold. In addition to the time to failure, the suction (negative pore water pressure) distribution in the slope, the shape and depth of the failure surface are also evaluated. Properties of soil-water characteristic curve which affect the distribution of ...
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Çobanoğlu, Adil Baran; Binici, Barış; Department of Civil Engineering (2014)
Unreinforced masonry construction is still widespread among many urban and rural areas, in developing countries such as Turkey. In order to prevent any loss of lives during an earthquake, ensuring the safety of these buildings is crucial. The buildings which are located in earthquake prone regions should be investigated and assessed so that necessary precautions can be taken. Therefore, several questions and concerns regarding the application of the assessment procedure, the assumptions and risk decision fo...
Effect of ground perlite incorporation on the performance of blended cements
Erdem, T. K.; Akgül, Çağla; Tokyay, Mustafa; Erdoğan, Turhan Y. (2007-06-13)
Perlite is a volcanic rock that contains relatively high amounts of SiO2 and Al2O3. Due to its proper chemical composition and glassy structure, it can be used as a pozzolanic addition in blended cements. In this study, ground perlite was used as a cement replacement material in blended cements. Several mortar mixes were prepared to investigate the performance of those cements. The results showed that perlite incorporation caused early age strength losses when compared to the control mortars containing only...
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Orhan, M.; Isik, N. S.; Topal, Tamer; Ozer, M. (Springer Science and Business Media LLC, 2006-05-01)
Andesite exposed in different parts of Ankara has different weathering categories varying from fresh to residual soil. The geomechanical properties of the andesite are significantly affected by weathering. Buildings constructed especially in completely weathered and residual soil levels of the andesite have some geotechnical problems. In this study, the variation of the geomechanical properties of the andesite due to weathering is investigated in three selected sites of Ankara, through optical microscope, X...
Citation Formats
O. Cengiz, “Effects of pozzolan incorporation and curing conditions on strength and water resistance of natural gypsum pastes,” Ph.D. - Doctoral Program, Middle East Technical University, 2009.