CIE327hw2

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University at Buffalo *

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327

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Civil Engineering

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Apr 3, 2024

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pdf

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3

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CIE327hw2.doc S TATE U NIVERSITY OF N EW Y ORK AT B UFFALO Name: ____________________ Department of Civil, Structural & Env. Engr. Student # ___________________ Spring Semester 2023 Professor Kamran M. Nemati Grade: / 70 CIE 327 C IVIL E NGINEERING M ATERIALS Problem Set 2 Concrete Mix Design (Due: Tuesday, Febuary 28, 2023) This question is about the ACI Method of Proportioning Concrete Mixes. For this question assume the following data for the materials to be used. The Tables from the ACI standard are given in the class notes. Table I: The Materials Properties for this Problem. Cement Type I Coarse Aggregate Fine Aggregate Bulk Specific Gravity 3.15 2.70 2.60 Fineness Modulus 2.60 Dry-Rodded Unit Weight, pcf 102 Take the weight of water to be 62.4 lb/ft. a) Suppose the slump of an ACI mix concrete will be 6 inches , and the maximum size coarse aggregate will be 1 inch . i.) What will be the approximate amount of mixing water for a non-air-entrained mix? ii.) What will be the approximate amount of mixing water for an air-entrained mix? b) The ACI method of mix proportioning concrete takes a scientific approach to choosing the coarse aggregate. i.) How much coarse aggregate will be used for any concrete proportioned by the ACI method with these materials? [Answer this on the basis of the volume of dry-rodded coarse aggregate per unit volume of concrete.]
CIE 327 Civil Engineering Materials Problem Set 2Page 2 CIE327hw2.doc ii.) What is the rationale for the choice of coarse aggregate in the ACI method? [Hint: Describe why the dry rodded unit weight of the coarse aggregate given in Table 9-5 changes as a function of fineness modulus of the fine aggregate.] c) Assume that we will use the mix in a mild climate and we want 5000 psi strength . In addition, assume the slump will be 6 inches , and the maximum size coarse aggregate will be 1 inch . Fill in the information in Table II below for a non-air-entrained concrete mix. Table II. Concrete Mix Proportions - Initial Values Mix Information Units Calculations Mix Water/cu yd concrete lb Same as Part a.) (i) Air, estimated vol % Water-cement ratio wtl % Cement/cu yd concrete lb Vol;/ CA/cu yd concrete cu ft Same as Part b.) (i.) CA/cu yd concrete lb d) The next step in the ACI method requires finding the amount of fine aggregate (FA) by the absolute volume method. Fill in the information in Table III below. Table III. Concrete Mix Proportions - Finding the volume of FA (ft 3 ) Vol cement (per cu yd) cu ft Vol water (per cu yd) cu ft Vol CA (per cu yd) cu ft Vol air (per cu yd) cu ft Total (per cu yd) cu ft Vol FA (per cu yd) cu ft (Problem is continued on next page...)
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