15. Concrete Mix Design (Local Aggregate).pdf
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- Solicitation number
- FA252125B0009
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This document contains two Concrete Mix Design specifications for Structural Concrete (TYPE IL and TYPE II) for a project on Ascension Island. Both designs specify a target strength of 4,000 PSI at 28 days, using Portland Cement (Type IL or Type II), #57 Stone from a government-owned local rock crusher, and imported standard silica sand. Key differences include the cement bag quantity per cubic yard (8 bags for Type IL, 7.5 bags for Type II) and water-cement ratios (.44 Lb for Type IL, .47 Lb for Type II). The specifications provide detailed mix proportions, design notes, and general instructions for concrete preparation, including provisions for water absorption, aggregate moisture conditions, and batch plant limitations specific to the Ascension Island project site.
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Concrete Mix Design Structural Concrete (TYPE IL)
Materials Portland Cement: Type IL Corse Aggregate: #57 Stone Local. From Ascension Island Rock Crusher (Government Owned) Fine Aggregate: Not Applicable. (Availability of local crusher fines is limited on Ascension Island) Sand: Imported Standard Silica Sand Water: Local Potable Air Content: 2% Entrapped Air Assumed Admixtures: Not Applicable.
Specified Strength:
4,000 PSI at 28 Days
Mix Proportions
Item Material Weight
(LBS)
Estimated Volume
(CF)
1 Water. (40 Gallons Per Cubic Yard) 334 5.35
2 Portland Cement. Type IL (8 Bags Per Cubic Yard)
752 8.00
3 #57 Stone. Ascension Island Rock Crusher 1261 8.08
4 Sand 1550 9.44
5 Air (Entrapped) 0.54
TOTALS 3897 31.41
Design Notes Slump = 4” +/- 1.5” Air Content = 2% Entrapped Water-Cement Ratio = .44 Lb
General Notes Concrete design is based on aggregate being saturated surface dry (SSD). Allowance is made for additional water for absorption by the aggregates based on 2% for the coarse aggregate and 6% for the fines/sand. Additional allowance made for adding up to 15 Gallons per CY based on current weather conditions (rain).
Due to limitations of the Government batch plant, the cement must be placed on top of the aggregate as it travels up the conveyor into the mixer truck.
The additional water needed for absorption is added with the balance of the water per the concrete design.
Up to 1.5 Gallons of water per CY may be added at final pour site to achieve desire slump.
Concrete Mix Design Structural Concrete (TYPE II)
Materials Portland Cement: Type II Corse Aggregate: #57 Stone Local. From Ascension Island Rock Crusher (Government Owned) Fine Aggregate: Not Applicable. (Availability of local crusher fines is limited on Ascension Island) Sand: Imported Standard Silica Sand Water: Local Potable Water Air Content: 2% Entrapped Air Assumed Admixtures: Not Applicable.
Specified Strength:
4,000 PSI at 28 Days
Item Material Weight
(LBS)
Estimated Volume
(CF)
1 Water. (40 Gallons Per Cubic Yard) 334 5.35
2 Portland Cement. Type II (7.5 Bags Per Cubic Yard)
705 3.59
3 #57 Stone. Ascension Island Rock Crusher 1261 8.08
4 Imported Sand 1550 9.44
5 Air (Entrapped) 0 0.54
TOTALS 3850 27.00
Design Notes Slump = 4” +/- 1.5” Air Content = 2% Entrapped Water-Cement Ratio = .47 Lb (Maximum Allowable Ratio = .50)
General Notes Concrete design is based on aggregate being saturated surface dry (SSD).
In general no more than 1 Gallon per CY of mix batching water should be added to the mix or the maximum water cement ratio would be exceeded and adversely affect the both the concrete strength and its long term durability.
Because of wind and humidity conditions, the aggregate may be dry prior to start of mixing operations.
Any water added for absorption should be added and pre-mixed a minimum of 15 minutes before adding in any cement or mix water may be on the order of 1.5 Gallons per CY.
Due to limitations of the Government batch plant, the cement must be placed on top of the aggregate as it travels up the conveyor into the mixer truck.
File details come from the government source that posted it. Updated .