Calculation of the maximum aggregate size, maximum diameters and minimum reinforcements separations, and minimum dimensions of the members
according to EHE-08 regulation (28.3.1, 37.2.4, 69 and 70).

• The maximum size of coarse aggregate used in concrete production is related with the reinforcement cover, and with the spacing between reinforcing bars, because small gaps or large aggregates can generate voids and defects in the concrete.
  
  
• Calculation programs use this parameter to calculate the minimum separation between reinforcements. Low values ​​of maximum aggregate size allow placing the reinforcement closest each other.
  
  
• The aggregates that make up the concrete must meet the general requirements specified in the EHE 08 28.3.
  
  
• As this program calculates various parameters that depend on the maximum aggregate size, you should introduce a chosen size and the program checks it at each element.
  
  

• At article 28.3.1 of the EHE-08 the maximum aggregate size is related with the cover, without specifying the type of renforcement. However in article 37.2.4 referres to this article indicating that only has to be met for the main reinforcement. Although in author's opinion the aggregate can generate concreting defects with columns styrrups also (not being main reinforcements), the result of this program is the strictly specified by the regulation.
  
  
• As the maximum aggregate size is different depending on whether the main reinforcement is horizontal or vertical, you could get different results if placing the wall horizontal reinforcement as outer or inner positioned. This program assumes that the horizontal reinforcement is outer because it is the most common situation to avoid vertical reinforcement buckling, generating smaller aggregate sizes and larger minimum thickness.
  
  
• The regulation makes a rough compilation for active and passive reinforcements since at section 69.4.1.1 where the separation between passive reinforcement is defined, reference is made to prestressed steel at joists and hollow-core slabs, while separations are defined specifically for prestressed reinforcement. Although the horizontal pitch is the same in both cases, it can be confusing with the vertical separation to be obtainable closer spacing for active pre-tensioned reinforcements that for passive reinforcement.
  
  
• The article 28.3.1 says that "When the concrete must pass between multiple reinforcement layers, it is desirable to use an aggregate size smaller than the rightful with limits a) or b) if determining" (In the comment on article 69.4.1.1 is indicated something similar). The author doesn't know how to interpret this paragraph as multiple layers can refer to more than one, which it is applicable to beams, slabs reinforced with two layers and walls, and do not specify how much smaller. It can be assumed that various layers on one side of the element is referred. Moreover, the author does not know whether there is mandatory to fulfill a convenience, ie if it is mandatory something should not be done but it is "desirable" to be done.
  
  

Version 25/08/2012