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Due to increasing volumes of fly ash production each year, new utilization areas must be found. A new application had been developed at Bogazici University. Fly ash with various weight percentages of rubber tire chips were mixed and compacted at a water content wet side of optimum. Sealed single ring infiltrometer and falling head permeability tests were conducted on these specimens with water and gasoline as the permeants. Unconfined compression and split tensile strength tests were conducted to evaluate the mechanical behavior of the proposed liner material. When gasoline was permeated through rubber-fly ash specimens, a decrease was observed in the permeability as compared to that measured during water permeation. This decrease is due to the physical characteristic of rubber, expansion upon contact with gasoline. The expanded rubber holds some portion of the gasoline in itself, while sealing the voids and blocking the passageways for further leakage. For the above-mentioned technique, patent protection has been applied. This technique has a good application in the field because the liability for the underground petroleum storage tanks will decrease considerably when this technique is used.

The increasing construction of high-rise buildings in recent years had led to a demand for lightweight, high-strength concrete. In this study, the compositions of the matrix and the air void structure of aerated mortar containing silica fume were investigated as the basis for manufacturing lightweight, high-strength concrete. Mortars made with cement containing silica fume and fine or ultra-fine silica stone powder, having a particle size between that of cement and silica fume, were tested; the properties of cement paste in fresh and hardened conditions were improved. The compressive strength and the air void structure of prefoamed aerated mortars were determined and their relationship studied. Based on the results, it was confirmed that lightweight, high-strength concrete could be made with an effective combination of aerated mortar containing silica fume and lightweight coarse aggregate.

The workability, strength, and durability of concrete are affected by particle distribution and chemical composition of cement. So, a cement which has ideal particle distribution and chemical composition is needed is needed for making high performance concrete. This kind of cement can be realized by blending portland cement, silica fume, and blast furnace slag, because they have different particle distributions and chemical compositions. In this paper, the triple blended cement was composed of 10 percent silica fume, 30 percent blast furnace slag, and 60 percent portland cement as it had suitable chemical composition and the densest particle distribution in portland cement or portland cement admixed by silica fume or blast furnace slag in this research. The hydration process of the triple blended cement was similar to the portland cement, but the heat of hydration and Ca(OH) 2 content in the hydrates were much lower than that for portland cement. It was found that the porosity of the hardened paste was so low that it was half of that in portland cement paste. The R 2O in its pore solution was only 88 percent of that in pore solution of portland cement paste. This fact means the triple blended cement may reduce the alkali-silica reaction of concrete. The flows of the fresh mortars made by the triple blended cement were higher or lower than the flow of the control mortar depending on the specific surface area of silica fume used. The compressive strengths of the mortar were higher than that of the control mortar as its denser paste. Because of the low Ca(OH) 2 content in the hydrates and R 2O in the pore solution, the resistance of the mortars to sulfate attack and alkali-silica reaction was high. However, the drying shrinkage of the mortars made with the triple blended cement was higher than that of the control mortar.

Canada Centre for Mineral and Energy Technology (CANMET) has an ongoing project dealing with the role of supplementary cementing materials in concrete technology. As a part of this program, a new type of concrete known as high-volume fly ash concrete has been developed. In this type of concrete, the water and cement (ASTM Type I) contents are kept very low, about 115 and 155 g/m 3, respectively, and the proportion of low-calcium fly ash in the total cementitious materials content is about 56 percent. This type of concrete has excellent mechanical properties and durability characteristics. In spite of very good properties shown by the high-volume fly ash concrete, one concern about the use of this type of concrete is its performance at early ages due to its low cement content and the slow reaction process of fly ash. This can be an obstacle for the use of this type of concrete when compressive strengths over 10 MPa at one day are needed or when proper curing cannot be provided for a long period of time. One way to improve the early-age properties of this type of concrete is to use ASTM Type III portland cement. Therefore, a study was undertaken to develop engineering data base on the high- volume fly ash concrete using ASTM Type III cement. Concrete mixtures were made using ASTM Type III portland cement from a source in the U. S. A. and three low-calcium fly ashes also from source in the U. S. A. A reference mixture (without fly ash) was also made for comparison purposes. The use of ASTM Type III cement instead of Type I cement noticeably improved the early-age strength properties of the high-volume fly ash concrete incorporating the fly ashes investigated in this study; this was done without having any detrimental effect on long-term properties of the concrete. The one- day compressive strengths were about 5 to 8 MPa higher than those of the high- volume fly ash concrete made with the same fly ash and Type I cement. The use of Type III cement also shortened slightly the setting time of the high-volume fly ash concrete. Durability characteristics and drying shrinkage of high- volume fly ash concrete made with ASTM Type III cement were no different than those for the concrete made with Type I cement.

The purpose of this study was to examine the mechanical and durability properties of high-volume fly ash concretes for structural applications. Four concrete mixtures were prepared with the amount of fly ash, from Italian source, varying from 0 to 50 percent by weight of total cementitious materials. A large number of concrete specimens were cast and tested to determine the compressive, flexural, and splitting tensile strengths, modulus of elasticity, fracture parameters, concrete-steel bond properties, drying shrinkage, and durability properties. The results of this study showed that high-volume fly ash concrete has considerable potential in a wide variety of structural applications.