ACI 304.3R-96 Heavyweight Concrete: Measuring, Mixing, Transporting, and Placing

ACI 304.3R-96 Heavyweight Concrete: Measuring, Mixing, Transporting, and Placing. 2.5—Heavyweight mortar and grouts Select heavyweight mortars and grouts have been manu- factured to meet specifc needs. Iron mortar concretes produced commercially by manufacturers for shielding concrete can exhibit adequate performance. However, these materials should be tested prior to use for density, compres- sive strength, and the necessary properties for shielding. Heavyweight aggregates by themselves or in part replaced by well-graded fne steel aggregates can be formulated with cementitious materials to get densities of 150 to 300 lb/ft 3 (2403 to 4806 kg/m 3 ) (Table 2.5). User will need to ensure that the mixture qualifes to the specifed job requirements. 3.2—Mixture proportioning Procedures outlined in ACI 211.1 should be used for mixture proportioning. Typical proportions for heavyweight concretes used on projects in Canada and the United States are shown in Table 3.2. A recent example of an ultra-heavyweight concrete was proportioned by combining heavyweight mineral aggregate and steel particles. Approximately 400 yd 3 (306 m 3 ) of this ultra-heavyweight concrete with fresh density between 330 and 332 lb/ft 3 (5290 and 5320 kg/m 3 ) and 6000 psi (41 MPa) (minimum) compressive strength was placed near Boston< MA, in the summer of 2015 (Noller et al. 2016). 3.2.1 Conventionally placed heavyweight concrete—The concrete mixture should be proportioned to provide the desired compressive strength, density, and adequate work- ability. Also, the chemical constituents and fxed water content of the resulting mixture must provide satisfactory shielding properties (Davis 1972b). As noted in this report’s Section 1.1, Introduction, the water bound in the cementi- tious component of concrete is necessary to supply hydrogen for shielding and neutron attenuation. 7.1—Samples and tests Heavyweight concrete materials and heavyweight concrete should be sampled and tested prior to and during construc- tion to ensure conformance with applicable standards, specifcations, and key properties. Guidance presented in these standards as well as the contractor’s previous expe- rience with the same materials will determine the required frequency of testing. The complexity of structures in which heavyweight concrete is placed usually precludes the possibility of taking test cores. Furthermore, extraction of test cores from concrete containing coarse metallic aggregate particles is costly. Unless great care is exercised, the metallic particles will be torn loose from the matrix, destroying both the bit and the core sample. It is therefore of the utmost importance that a thorough quality control program be established...