Aggregate packing and -void saturation in mortar and concrete proportioning |
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Authors: | Stefan Jacobsen Bård Arntsen |
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Affiliation: | (1) Department of Structural Engineering, Norwegian University of Science and Technology – NTNU, Trondheim, 7491, Norway;(2) Norut Teknologi AS, Lodve Langes gt.5, Narvik, 8505, Norway |
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Abstract: | Proportioning was studied by measuring aggregate packing (C) and filling of aggregate void space (1?C) with varying volumes of cement paste ((V_{rm p})) or matrix ((V_{rm matrix})), i.e., all material <0.125 mm. Eleven widely different normal density aggregates with C = 0.57 to 0.71, i.e., aggregate void content (1?C) = 0.29 to 0.43, were used at constant w/c = 0.38 and flowing consistency and varying dosage of water reducer and paste- and matrix volume. Analysing plots of four excess phase volumes (paste with/without air, matrix with/without air) versus aggregate void space showed constant aggregate void saturation ratios. Both paste- and matrix-aggregate void saturation ratio can be used with the best estimate ((V_{rm p}-V_{rm air})/{(1-C)}=1.15) per (hbox{m}^{3}). Including air voids in paste- or matrix volume improved correlation so air void content must be included in the normalized paste aggregate void saturation ratio ((k=V_{rm p})/[(1?C) (V_{rm tot})]). Simple measurements of aggregate packing are thus very useful. Cost per unit material, per unit fresh (slump, flow diameter) or hardened (compressive strength) property were used to show the cost efficiency of the mixes. The ranking of cost/MPa strength and cost/mm consistency is similar to ranking of total concrete cost for the 11 aggregates with a certain scatter though. |
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Keywords: | Mortar Concrete Proportioning Aggregate Packing Paste volume Admixture Fresh properties |
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