Shrinkage Compensating Admixture or SRA

CONEX® is a powdered admixture used for the compensation and total overall reduction of net shrinkage for Portland cement concrete. Its functional mechanism is based on the formation of an expansive component. CONEX® is an expansive Type G component, which produces a calcium hydroxide platelet crystal system, as specified in ACI 223.

Features & Benefits

• The expansion characteristics of CONEX® allow for net shrinkage reduction for concrete
• Use of this admixture does not cause any slump loss and may be used in conjunction with other Euclid Chemical admixtures
• Will not affect the mechanical strengths
• It is compatible with the majority of Portland cements
• CONEX® does not affect the air content, set time, or other characteristics of fresh concrete
• The addition of CONEX® should not adversely affect freeze-thaw and salt scaling resistances given that an adequate air void system is provided
• Expansion process is not through ettringite formation

Applications

• Flatwork concrete
• Bridge decks
• Parking structures
• Interior/Exterior
• Arena/Artificial skating rinks
• Walls/Parapets
• Storage tanks
• Watertight construction
• Toppings
• Piers

Specifications / Compliances

• Meets ASTM C494 Type S admixture
• ANSI/NSF STD 61 registered

CONEX is a dry powdered material that has early expansive characteristics. When CONEX comes into contact with water one of the components reacts immediately, similar to cement, and has an initial expansive quality. CONEX can function as a shrinkage reducing material when used at the lower rate of its suggested dosage range (3-6 % by weight of cement). Shrinkage compensation is achieved when using CONEX at the higher rate of the recommended dosage range (6-10% by weight of cementitious.

When used correctly, this early expansion is enough to compensate for typical shrinkage which will be experienced within the concrete pore structure, resulting in greatly reduced overall shrinkage of the concrete. The reaction of CONEX is generally complete in the first 24 hours after exposure to water. 

For this reason, when performing length change testing in accordance with ASTM C-157, the specimens must be demolded and initial reading taken at 12 hours. If the initial shrinkage reading is delayed, the shrinkage results will appear as though the CONEX did not perform. CONEX should be used when shrinkage requirements demand shrinkage reduction of greater than 50% when compared to a reference concrete of the same design and materials.