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The concept of highly-flowable concrete was developed from the transformation of underwater concreting ideas to the concreting of structures on land. Therefore, the general properties of highly-flowable concrete are similar to those for concreting under water. The viscosity of highly-flowable concrete is high so that segregation of the coarse aggregate from the concrete can be eliminated. The slump flow of highly-flowable concrete is greater than 600 mm so as to increase its flowability. The slump flow is defined as the diameter of slumped concrete. The distinctive feature of the mixture is that a larger proportion of fine material is used in it. The high viscosity and large amount of fines increase its resistance to segregation. In the method of mixture proportioning of highly-flowable concrete proposed by the authors, a high-range, water-reducing admixture (HRWRA) is used to increase the slump flow. Furthermore, a segregation-reducing agent is used to minimize the segregation, although a large proportion of fines somewhat increases the viscosity of concrete. Limestone powder, which is a relatively low reactive material, is used to reduce the heat of hydration and shrinkage. In the proposed method of mixture proportioning, it is possible to choose the required average strength, water content, and fine aggregate-total aggregate ratio to suit special and particular conditions of concrete structures under various environmental conditions.

Because of increasing annual production volumes of fly ash, large volume applications, such as aggregate production, are beneficial in solving the disposal problem of fly ash while making economical use of a mineral resource. Aggregates have been produced from high calcium fly ash of Soma Thermal Power Plant and their engineering properties measured. For high volume utilization of fly ash, aggregate production involving pelletization and pressing into specially designed molds has been carried out successfully. Mechanical property and durability tests were conducted on the cured lightweight fly ash aggregates; five percent by weight lime addition to fly ash showed the best performance. It was also shown that different shapes of aggregates can be produced using the pressing technique.

In a program covering a wide range of mixtures, three portland cements and two ground granulated blast furnace slags (GGBS) were used to investigate the relationship between alkali content and ASR expansion. Length changes were monitored, for several years, on concrete prisms made with a reactive natural aggregate. The prisms were moist cured at 20 C and 38 C. Storage at 38 C was found to be an accelerated test which correlated will with storage at 20 C. At 20 C, the rate of expansion was some four times slower than at 38 C. Nonetheless, there was very good consistency between the two temperatures in classifying mixtures either expanding or nonexpanding. Current indications are that the magnitudes of ultimate expansions are independent of temperature. The mixtures containing GGBS tolerated much greater alkali contents in the concrete without expansion. This effect was more pronounced for higher proportions of GGBS. The results of the program are discussed in this paper in relation to various rules which have been proposed to take advantage of the effectiveness of GGBS in preventing ASR.

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.