Published by department of transportation
-1.04 PAYMENT Not Used 90-2 MINOR CONCRETE 90-2.01 GENERAL
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- 90-2.01D Quality Assurance
- 90-2.02A General Reserved 90-2.02B Cementitious Material
90-1.04 PAYMENTNot Used 90-2 MINOR CONCRETE 90-2.01 GENERAL90-2.01A SummarySection 90-2 includes specifications for furnishing and protecting minor concrete. 90-2.01B DefinitionsReserved 90-2.01C SubmittalsIf required by the following table, submit compressive strength test results with the mix design that verify the minimum required compressive strength:
Submit the concrete mix design before using the concrete in the work and before changing the mix proportions. Submit a proposed combined aggregate gradation. After authorization of the gradation, the aggregate furnished for minor concrete must comply with that gradation. If requested, submit periodic test reports of the aggregate gradation furnished. The Engineer may waive the specifications for gradation if the Engineer determines that furnishing a gradation is not necessary for the type or quantity of concrete work to be constructed. Before placing minor concrete from a source not previously used on the Contract, submit a certificate of compliance stating that the minor concrete to be furnished complies with the Contract requirements, including the specified minimum cementitious material content. Submit a weighmaster certificate as an informational submittal with each load of ready-mixed concrete at the concrete discharge location. The weighmaster certificate must show the date and time the load left the batching plant and, if hauled in a truck mixer or agitator, the time the mixing cycle started. 90-2.01D Quality AssuranceSection 90-1.01D(5) and the specifications for uniformity in section 90-1.02A do not apply to minor concrete. The Engineer may perform tests and inspect the facilities, materials, and methods for producing the minor concrete to ensure that it is of suitable quality for use in the work. The Engineer verifies compliance with the specified cementitious material content by testing under California Test 518 for cement content. For testing purposes, SCM is considered to be cement. Adjust the batch proportions as necessary to produce concrete having the specified cementitious material content.
90-2.02 MATERIALS90-2.02A GeneralReserved 90-2.02B Cementitious MaterialMinor concrete must contain at least 505 pounds of cementitious material per cubic yard. You may use rice hull ash as an SCM. Rice hull ash must comply with AASHTO M 321 and the requirements for the quality characteristics shown in the following tables:
For the purpose of calculating the equations for the cementitious material specifications, consider rice hull ash to be represented by the variable UF. 90-2.02C AggregateSections 90-1.01C(2) and 90-1.02C do not apply to minor concrete. The aggregate must be clean and free from deleterious coatings, clay balls, roots, and other extraneous material. The maximum aggregate size must not be larger than 1-1/2 inches or smaller than 3/4 inch. You may use crushed concrete and reclaimed aggregate if they comply with the specifications for aggregate. 90-2.02D WaterSection 90-1.02D does not apply to minor concrete. Water used for washing, mixing, and curing must be free from oil, salts, and other impurities that would discolor or etch the surface or have an adverse affect on the concrete quality. 90-2.02E ProductionSections 90-1.02F, 90-1.02G(1), 90-1.02G(2), 90-1.02G(3), and 90-1.02G(4) do not apply to minor concrete. Store, proportion, mix, transport, and discharge the cementitious material, water, aggregate, and admixtures in compliance with recognized standards of good practice that result in thoroughly and uniformly mixed concrete suitable for the intended use. Recognized standards of good practice are outlined in various industry publications, such as those issued by ACI, AASHTO, or the Department. Use a quantity of water that produces concrete with a consistency that complies with section 90-1.02G(6). Do not add water during hauling or after arrival at the delivery point unless allowed by the Engineer. Discharge ready-mixed concrete from the transport vehicle while the concrete is still plastic and before stiffening occurs. Take whatever action is necessary to eliminate quick stiffening, except do not add water. Conditions contributing to quick stiffening are: 1. Elapsed time of 1.5 hours in agitating hauling equipment or 1 hour in nonagitating hauling equipment 2. More than 250 revolutions of the drum or blades after introduction of the cementitious material to the aggregates 3. Concrete temperature over 90 degrees F The mixing time in a stationary mixer must be at least 50 seconds and no more than 5 minutes. The minimum required revolutions at mixing speed for transit-mixed concrete must be at least that recommended by the mixer manufacturer and must be increased as needed to produce thoroughly and uniformly mixed concrete. If you add a high-range water-reducing admixture to the concrete at the job site, the total revolutions must not exceed 300.
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