The importance of specifying proper aggregate grading for achieving satisfactory performance in pavement applications has long been recognized. To improve the specifications for superior performance, there is a need to understand how differences in aggregate gradations within the acceptable limits may affect unbound aggregate base behavior. The effects of gradation on strength, modulus, and deformation characteristics of high-quality crushed rock base materials are described here. Two crushed rock types commonly used in constructing heavy-duty granular base layers in the State of Victoria, Australia, with three different gradations each were used in this study. The gradations used represent the lower, medium, and upper gradation limits for heavy-duty base materials specified by the State of Victoria’s road agency (VicRoads). Modified compaction tests were conducted first to determine the moisture-density relationship of all mixes. Further, California bearing ratio (CBR), unconfined compressive strength (UCS), and repeated load triaxial (RLT) tests were then performed to study the effects of different gradations on strength, resilient modulus (MR), and deformation resistance. Further, permanent deformation and MR results were modeled using two popular models for each to explain the effect of gradation on the mixtures’ characteristics. The results indicate that the gradation that provides the best characteristics varies depending on the type of material used. For the materials tested here, coarse and medium gradations provide the best mixture characteristics in relation to CBR, MR, and permanent deformation. Fine gradation mixtures of these materials have lower values of these measures but are still considered acceptable considering relevant specification for the intended application.
Background: spontaneous abortion constitutes one of the most important adverse pregnancy outcomes affecting human reproduction, and its risk factors are not only affected by biological, demographic factors such as age, gravidity, and previous history of miscarriage,but also by individual women’s personal social characteristics, and by the larger social environment. Objective:To identifyEnvironmental effects on Women's with Spontaneous Abortion. Methodology:Non-probability(purposive sample)of(200) women, who were suffering from spontaneous abortion in maternity unitfrom four hospitals at Baghdad City which include Al-ElwiaMaternity Teaching Hospital, and Baghdad Teaching Hospital at Al-Russafa sector. Al–karckhMaternityHospita
... Show MoreThe tunnel’s stability during construction is a very important matter. Some methods have been proposed for stability evaluation, but the hazard warning levels (HWLs) are more applicable among these methods. Despite monitoring and applying HWLs, several collapses in Shibli twin tunnels in Iran have cast doubts on the accuracy of this criterion in the presence of water. In this study, the critical strains under different water contents were measured through uniaxial compressive strength tests on 11 different shale and marl samples. A comparison of laboratory tests and numerical results shows that the influence of the moisture content on the critical strain is negligible. In addition, the results show that there is no dir
... Show MoreThe Mishrif reservoir (Cenomanian - Turonian) in the Z, H, B and N oilfields in southern Iraq was investigated to clarify how nickel, vanadium, asphaltene, NSO and sulfur content affect the crude oil quality. The GC-Mass and ICP-MS analyses were used to provide fruitful hydrocarbon results. Classification of crude oil based on API gravity broadly indicates the oil's density and general properties. Typically, lighter crude oils are easier to refine, yield higher percentages of valuable products such as gasoline and diesel, and have a higher market value. Heavier crude oils require more processing and may yield more residual products, such as heavy fuel oil and asphalt. The Mishrif crude oil was classified as a medium sour crude oil c
... Show MoreThis paper is devoted to investigate experimentally and theoretically the structural behavior of reinforced concrete hollow beams which have internal transverse ribs under effect of shear. The number of the internal ribs is the major variable adopted in this research, while, the other variables are kept constant for all tested specimens. The experimental part includes poured and test of four (200x300x1200mm) beam specimens, three of these specimens were hollow with different locations of internal ribs and one of them was solid. The experimental results indicated that the shear strength are increased (33%) to (60%) for beams containing internal ribs in comparison with reference beam. Also, the change of beam state from ho
... Show MoreBackground: The aim of the study was to investigate the effect of surface treatments of zirconia (grinding and sandblast with 50μm, 100 μm) on shear bond strength between zirconia core and veneering ceramic. Material and methods: Twenty-eight presintered Y-TZP ceramic specimens (IPS e.max ZirCAD, Ivoclar vivadent) were fabricated and sintered according to manufacturer’s instructions. The core specimens were divided randomly in to 4 groups, group 1: no surface treatment, group2: zirconia specimens were ground with silicon carbide paper up to1200 grit under water cooling, group3: zirconia specimens were ground and sandblast with 100 μm alumina, group 4: zirconia specimens were ground and sandblast with 50 μm alumina. Surfa
... Show MoreCeramic to metal joining technique, which was used in this investigation includes the use of active filler alloy as a sandwich between the alumina and kovar alloy for brazing. High purity powdered metals of silver, copper, and additives of titanium were used to prepare the active filler alloy, through compacting the mixed powders and alloying in a furnace with argon atmosphere at the temperature of 800oC for 10 minutes. To use it as an active filler metal, it has been modified to a proper thickness. Two groups of alumina were prepared with different sintering temperatures (1450oC and 1650oC) and each group was tested under atmospheric pressure, vacuum furnace pressure of 2*10-4 torr and vacuum furnace pressure of 2*10-6 torr. All the pro
... Show MoreRoller-Compacted Concrete (RCC) is a zero-slump concrete, with no forms, no reinforcing steel, no finishing and is wet enough to support compaction by vibratory rollers. Because the effectiveness of curing on properties and durability, the primary scope of this research is to study the effect of various curing methods (air curing, emulsified asphalt(flan coat) curing, 7 days water curing and permanent water curing) and different porcelanite (local material used as an Internal Curing agent) replacement percentages (volumetric replacement) of fine aggregate on some properties of RCC and to explore the possibility of introducing more practical RCC for road pavement with minimum requirement of curing. Cubes specimens were sawed from the slab
... Show MoreCeramic body as a refractory was prepared by using shamoot, which is prepared by firing kaolin Duekhla at 1450 ºC at 2hr ,Flint clay ,Asbestos fiber(Anthophylite type)and Sodium silicts,Phosphoric acid solution as a binder . After miling, siving ,and mixing ,samples were formed, followed that drying, firing at different temperature. Phyical ,thermal and mechanical properties were measured .The conclusion behind the results that the refractory prepared from; 37.5% shamoote,25% Asbestos ,37.5% Flint clay and Phosforic acid solution fired at 1300 ºC gave a refractory material having melting temperature ;1490 ºC, thermal shock resistance 7 cycle, thermal conductivity 2.1w/m2.K, apperan
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