Building Code of the Philippines(1)

Satisfactory weldability bar and rod mats for

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Unformatted text preview: engths greater than shown in Table 5.04-A may be used provided that the relationship between strength and water-cement ratio for the materials to be used has been previously established by reliable test data and the resulting concrete satisfies the requirements of Section 5.04(e). Where previous data are not available, concrete trial mixtures having proportions and consistency suitable for the work shall be made using at least three different water-cement ratios (or cement content in the case of lightweight aggregates) which will produce a range of strength encompassing those required for the work. For each water-cement ratio (or cement content), least three specimens for each age to be tested shall be made, cured and tested for strength in accordance with ASTM Specifications C39 and C192. The strength tests shall be made at 28 days or the earlier age at which the concrete is to receive load, as indicated on the plans. A curve shall be established showing the relationship between water-cement ratio (or cement content) and compressive strength. The maximum permissible water-cement ratio for the concrete to be used in the structure shall be that shown by the curbe to produce an average strength to satisfy the requirements of Section 5.04 (e) provided that the watercement ratio shall be no greater than that required by Section 5.04 (b). Where different materials are to be used for different portions of the work, each combination shall be evaluated separately. TABLE 5.04 - A MAXIMUM PERMISSIBLE WATER-CEMENT RATIOS FOR CONCRETE (METHOD 1)¹ MAXIMUM PREMISSIBLE WATER-CEMENT RATIO2 __________________________________________________________________________________________ SPECIFIED NON-AIR ENTRAINED AIR-ENTRAINED COMPRESSIVE CONCRETE CONCRETE STRENGTH AT 28 DAYS, PS I U.S. Gal. Per Absolute U.S. Gal. Per Ratio 94-lb. Bag of Ratio 94-lb. Bag of Absolute fC Cement 2000 2500 3000 3500 4000 7-½ 7-½ 6-¾ 5-¾ 5 by Weight 0.663 0.642 0.576 0.510 0.443 Cement 4 by Weight 7 0.620 6-¼ 0.554 5-¼ 0.465 4-½ 0.399 0.354 ¹The minimum cement content shall be no less than five bags per cubic yard (a bag weighing not less than 94 pounds) unless the mix is designed in accordance with the provisions of Method 2 of Section 5.04(c). 2 Including free surface moisture on aggregate. (d) Concrete Proportions and Consistency. The proportions of aggregate to cement for any concrete shall be such as to produce a mixture which will work readily into the corners and angles of the forms and around reinforcement with the method of placing employed on the work, but without permitting the materials to segregate or excess free water to collect on the surface. The methods of measuring concrete materials shall be such that the proportions can be accurately controlled and easily checked at any time during the work. (e) Strength Tests of Concrete. Tests of concrete shall be required for all concrete having an ultimate compressive strength in excess of 140 kilograms per square centimeter (2000 pou...
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