Concrete (C-8) · Lesson 6 of 7

Caltrans Concrete: Slump Limits, Free Water and Delivery Time

"Caltrans Concrete: Slump Limits, Free Water and Delivery Time" is lesson 6 of 7 in the Concrete (C-8) Learning Hub. It opens with "Where This Applies" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Where This Applies
  2. Slump Limits by Type of Work
  3. Free Water Cap
  4. Delivery Time and Revolution Limits
  5. Adding Water at the Delivery Point

The worked example in the course applies this lesson to a realistic job in 5 steps, from "Free-water cap" through "If withheld water is added".

What you'll be able to do

  • Explain the main idea of "Caltrans Concrete: Slump Limits, Free Water and Delivery Time" in plain language you can use on the exam.
  • Apply this step with confidence: "Free Water Cap".
  • Apply this step with confidence: "Delivery Time and Revolution Limits".
  • Apply this step with confidence: "Adding Water at the Delivery Point".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
CALTRANS CONCRETE: SLUMP, WATER, DELIVERYSection 90-1.02G, 2025 Caltrans Standard SpecificationsSLUMP LIMITS, REINFORCED CONCRETESection over 12 in thick: nominal 1-3, max 5Section 12 in or less: nominal 1-4, max 601234567nominal 1-3max 5Example: 14 in thick reinforced wallmeasured 4.5 inOver nominal: adjust later batches. Over max: do not use.Slump in inches, ASTM C143 as named in 90-1.02G(6)LOAD TICKET CHECKTime since batching: 40 of 90 minDrum revolutions: 180 of 250Concrete at 86 F is above 85 F:allowed time may be less than 1.5 hFree water cap, 650 lb cementitious:310 + 20 = 330 lb per cu ydWater at the truck: one addition, before1/4 cu yd is discharged, then 30 more revs180 + 30 = 210 revolutions, 40 left of 250Slump 4.5 in is usable (max 5); adjust next batches toward 1-3 inTime and revolutions are fine now; at 86 F the time limit may be shorter2025 Caltrans Standard Specifications 90-1.02G(3) and 90-1.02G(6)Source: 2025 Caltrans Standard Specifications 90-1.02G(3) Transporting, 90-1.02G(6) Slump and free waterCC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Where This Applies

The 2025 Caltrans Standard Specifications, Section 90 Concrete, govern concrete on work whose contract includes them, such as Caltrans projects. The building codes tell you what the structure needs; Section 90 tells you how the delivered concrete is controlled, and on a job that includes it the printed numbers are the contract.

Step 2: Slump Limits by Type of Work

90-1.02G(6) regulates mix water so that slump (tested under ASTM C143 as the spec names it) or penetration (California Test 533) falls in a nominal range. Reinforced concrete structures with sections over 12 inches thick: nominal slump 1 to 3 inches, maximum 5. Sections 12 inches thick or less: nominal 1 to 4, maximum 6. Concrete placed under water: nominal 6 to 8, maximum 9. CIP concrete piles: nominal 5 to 7, maximum 8. Concrete pavement and nonreinforced members are controlled by penetration only. If the result exceeds the nominal range, adjust later batches; do not use a batch that exceeds the maximum.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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