When cement content and slump remain constant, less mixing water is required. The resulting decrease in the water-cement ratio helps to offset possible strength decreases and improves other paste properties, such as permeability. When you want air entrainment for a reason other than durability, such as to improve workability or cohesion or to improve strength in low cement factor concrete, you can use air contents lower than those required for durability. Copyright permission not granted for electronic media. Examples are exterior beams, columns, walls, girders, or slabs that do not contact wet soil or receive direct application of deicing salts.
Examples are pavements, bridge decks, curbs, gutters, sidewalks, or exterior water tanks or sumps.
Do not use it to compare mixes having wholly different proportions or containing different sizes of aggregates. When different batches are tested, changes in slump indicate changes in materials, mix proportions, or water content. Table 17-4 gives recommended slump ranges for various types of construction. The following are some basic guidelines and an example to help you in performing the steps related to mix design by the trial batch method. In the trial batch method of mix design, use actual job materials to obtain mix proportions.