| Summary: | 碩士 === 逢甲大學 === 土木工程學系 === 104 === To achieve the desired permeability, water permeable concrete tend to have reduced strengths. Also, if water permeable concrete adopts mixing designs with inadequate volumes of mortar and lack fine aggregates, the resulting material would have compromised workability. Coating the mortar on aggregate surfaces would also increase the surface area of contact with air, which further affects workability. This research thus used aggregate grades of 9.5 mm to 4.75 mm for coarse aggregates, added fine aggregate, and employed the mortar coefficient method to design water permeable concrete mixtures for the purposes of improving workability, strength, and water permeability of the resulting water permeable concrete so that it becomes more applicable to different types of construction projects.
Results showed: A. Dry unit weight when water permeable concrete created using the experimental method range from 1,576 kg/m3 to 2,082kg/m3; saturated surface dry unit weight range from 1,720kg/m3 to 2,286 kg/m3; water absorption range from 0.05% to 11.77%; porosity range from 0.1% to 21.56%. All these figures are largely compliant to the standard assessment requirements for high performance water permeable green construction materials. B. Flow tests: Flow value is: inversely related to target porosity, proportionate to water-cement ratio, proportionate to mortar coefficient, and proportionate to sand content. Flow values range from 6.30% to 58.43%. C. Water permeability tests: Water permeability is: proportionate to target porosity, inversely related to water-cement ratio, inversely related to mortar coefficient, and proportionate to sand content. Water permeabilities range from 5.4 × 10-2 cm/sec to 12.7 × 10-2 cm/sec. D. Pressure resistance strength tests: Pressure resistance strength is: inversely related to target porosity, proportionate to water-cement ratio, proportionate to mortar coefficient, and proportionate to sand content. Pressure resistance strengths range from 57 kgf/cm2 to 268 kgf/cm2.
Figures 4-6-2 to 4-6-5 provide a number of mixture designs that can be used by the construction sector as a reference for the specified pressure resistance strengths and permeability coefficients. When considering pressure resistance strength and permeability coefficient at the same time, the optimal conditions would be 35% porosity, water-cement ratio of 0.3, mortar coefficient of 1.35, and sand content of 0.2 in order to achieve a flow value of 24.23%, permeability coefficient of 0.082 cm/sec, and pressure resistance strength of 193 kgf/cm2.
Keywords: ACI 211.3 Volume Method, mortar coefficient method, water permeable concrete, permeability coefficient, pressure resistance strength
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