Engineered concrete

[...]... Maximum W/C Ratio by Weight for Normal Weight Concrete Exposure Condition Concrete protected from exposure to freezing and thawing or the application of deicer chemicals Select the w/c ratio on the basis of strength, workability, and finishing needs Concrete intended to be watertight: a Concrete exposed to fresh water b Concrete exposed to brackish water or sea water Concrete exposed to freezing and thawing... satisfactory for the production of a good concrete OBJECTIVES IN DESIGNING A CONCRETE MIXTURE Concrete may be considered as composed of four basic separate ingredients: cement, coarse aggregates, fine aggregates, and water Another way of looking at concrete is that of a graded mixture of fine and coarse aggregates held together by wetted cement Still another way of viewing concrete is that the coarse aggregates... conditions such as for tremie concrete (concrete placed under water) to ≥ 390 kg/m3, or for a very cold climate where the concrete is subject to freezing and thawing cycles; the cement content should be ≥ 335 kg/m3 Adapted from the ACI Committee 302 Report, “Guide for Concrete Floor and Slab Construction.” THE INTERNATIONAL SYSTEM OF MEASUREMENTS Illustrative Problem for Concrete Mix Design by the Absolute... durability, and workability of a concrete are cleanness, grading, hardness, and shape Usually the aggregates are stronger than the concrete from which they are made A coating of dirt or dust on the aggregate will reduce the strength of concrete because it prevents the particles from properly bonding to the mortar A well-graded aggregate mix is essential to obtaining an economical concrete of good quality If... deicing chemicals For corrosion protection for reinforced concrete exposed to deicing salts, brackish water, sea water, or spray from these sources a 0.50 0.45 0.45 0.50 0.45 0.40 Air-entrained concrete Adapted from the ACI 318 Committee Report, “Building Code Requirements for Reinforced Concrete. ” Table 5 Volume of Coarse Aggregate Per Unit Volume of Concrete as per ASTM Designation: C 29 Maximum Size of... Requirements for Reinforced Concrete. ” is computed This standard deviation is introduced into two equations that in turn yield a modification factor In effect, the design objective then becomes to prepare a concrete with a compressive strength of f ′cr, which is greater than the specified design concrete strength f ′c Since there are variations in the results obtained in any concrete, the objective is... in this book The unit weight of freshly mixed concrete is expressed in a weight per volume while the yield is calculated by dividing the total weight of all the materials batched by the unit weight of the freshly mixed concrete The term batch is not unique to concrete works It is simply the quantity of materials required for a single operation To produce concrete of uniform quality the materials must... Content Requirements for Various Slumps and Maximum Size Aggregates in the Concrete Mix Water Per kg/m3 of Concrete for Indicated Maximum Size of Aggregate in mma Slump (mm) 10 20 40 80 Nonair-Entrained Concrete 25–50 75–100 150–175 Approximate % entrained air 207 228 243 3 190 205 216 2 166 181 190 1 130 145 160 0.3 Air-Entrained Concrete 25–50 75–100 150–175 181 202 216 168 184 197 150 165 174 122 133... Press LLC Table 12 Approximate Relationship Between W/C and the Concrete Compressive Strength Water/Cement Ratio by Weight a Compressive Strength at 28 Days (psi ) Nonair-Entrained Concrete Air-Entrained Concrete 6000 5000 4000 3000 2000 0.41 0.48 0.57 0.68 0.82 0.35 0.40 0.48 0.59 0.74 a Values are the estimated average strengths for concrete containing not more than the percent of entrained air shown... Furthermore, in the case of a paving concrete, it is hardly ©2000 CRC Press LLC Table 13 Minimum Portland Cement Requirements for Normal-Density Concrete Maximum Size of Aggregate (in.) Portland Cementa (lb/yd3) 1 1/2 1 3/4 1/2 3/8 470 520 540 590 610 a Cement quantities need to be increased in cases of severe environmental conditions such as for tremie concrete (concrete placed under water) to ≥ 650 . Irving. Engineered concrete : mix design and test methods / Irving Kett. p. cm. (Concrete technology series) Includes bibliographical references. ISBN 0-8493-2277-4 (alk. paper) 1. Concrete. . Content of Concrete (C 138) ©2000 CRC Press LLC Slump of Hydraulic Cement Concrete (C 143) Air Content of Freshly Mixed Concrete by the Volumetric Method (C 173) Making and Curing Concrete. (E 11) SECTION III: TESTS FOR PORTLAND CEMENT CONCRETE Compressive Strength of Cylindrical Concrete Specimens (C 39) Flexural Strength of Concrete Using Simple Beam with Third-Point Loading