| Summary: | 博士 === 國立臺灣科技大學 === 營建工程系 === 100 === This study discusses the effects of the densified mixture design algorithm (DMDA) on the high-flowing fly ash concrete prepared using aggregates of varying density. Using the DMDA forward packing model (FPM), backing packing model (BPM), and the traditional mix design method, this study investigates the quality and quantity of slurry, and the quantity of mixing water in the slurry. The results indicate that varying slurry concentrations combined with a new mix design (altered from w/c to w/s) strengthens the uniformity of the concrete and reduces wear and tear on machines. Additionally, this study designed lightweight, normal, and heavyweight concretes of varying slurry quality and quantity using lightweight aggregates (with a specific gravity of 1.9, silt from the Shimen reservoir, and 1 cm in diameter), natural sand (with a specific gravity of 2.64), and steel balls (with a specific gravity of 7.8, and 0.5 and 1 cm in diameter), respectively.. We examined the engineering properties of concrete in both its newly mixed state and its hardened state. In its newly mixed state, we examined the workability and crack sensitivity. In its hardened state, we examined the compressive strength, ultrasonic pulse velocity, surface resistance, and chloride ion permeability. This study also explored crack sensitivity, changes in length, and volume stability of slurry. The results show that regardless of the density of coarse-aggregate concrete, the slurry volume in DMDA does not differ when the components are altered. The high-quality slurry ratio (low w/cm and w/c) provides a superior newly mix property, hardened behavior, and volume stability. This design is similar to the traditional mix design of using low w/c and high-strength concrete to improve the overall quality. The less slurry induces better engineering results, such as its workability, durability, and volume stability. To achieve volume stability of the slurry, early moisture curing (within the first 7 days) and reduced water quantity are required. Comprehensive analysis of the results indicates that limiting the water contained and water to solid ratio improves engineering properties, such as durability, and volume stability when less amount of good slurry is used.
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