10-1 Division 10 – Concrete Mixtures
Section 1001. Concrete Production Equipment and Facilities ......................... 10-3 Section 1002. Contractor Quality Control for Concrete ................................. 10-15 Section 1003. Quality Assurance (Acceptance) for Concrete ........................ 10-23 Section 1004. Portland Cement Concrete Mixtures ....................................... 10-31 Section 1005. Mortar and Grout Mixtures ...................................................... 10-36 Section 1006. Patching, Repair, and Overlay Mixtures ................................. 10-40
10-2 Notes
10-3 Section 1001. Concrete Production Equipment and Facilities
1001.01. Description This section consists of the equipment and facility requirements for making portland cement conc rete (PCC) . 1001.02. Materials Provide materials in accordance with the following sections : Portland Cement ................................................................................... 901 Slag Cement ......................................................................................... 901 Fly Ash .................................................................................................. 901 Coarse Aggregate 6A, 6AA, 6AAA, 26A, 29A, 17A .............................. 902 Intermediate Aggregate ......................................................................... 902 Fine Aggregate 2NS, 2SS .................................................................... 902 Concrete Admixtures ............................................................................. 903 Water .................................................................................................... 911 1001.03. General Requirements
A.Certified Batching Plants . Provide PCC from certified portable and stationary concrete batch plant facilities that meet the current requirements of the National Ready Mixed Concrete Association (NRMCA) or other Department -approved certification programs for automatic control and automatic syst ems including the following:
1.Plant Certification
a.Stationary Concrete Batch Plants. Maintain plant equipment, facilities, and associated weighing and batching devices during production. Schedule inspections and maintain valid plant certification . Provide fo r scale inspections at intervals no longer than 6 months . Enlist the services of a Michigan Registered Service Agency to certify the calibration and working order of the weighing system . Check the batching accuracy of volumetric admixture dispensers and volumetric water batching devices (including water meters) at intervals no longer than 6 months. Provide all documentation of inspections and certifications to the Engineer.
b.Portable Concr ete Batch Plants. At the start of production and annually thereafter and after every move, ensure that portable concrete batch plants meet the requirements of subsection MDOT Standard Specifications for Construction Section 1001
10-4 1001.03.A.1.a. Provide documentation of inspections and
certifications to the Engineer . Clearly display current inspection reports, certifying that scales and volumetric batching devices meet the required tolerances at each plant facility . Display a photocopy of the inspection checklist, completed by the inspecting a gency, at each plant fac ility before providing material to the project . Display the Certificate of Conformance at each plant facility. The Department may inspect batching equipment, facilities, and associated weighing and batching devices and review the qualifications of private plant and scale inspectors or inspecting agencies.
2.Batch Tolerances. Provide batching equipment meeting the tolerances specified in the NRMCA checklist as follows:
a.Cementitious Materials. Provide cementitious materials within ±1% of the required weight or for loads less than 30% of the scale capacity, within ±0.3% of the scale capacity.
b.Aggregates. Provide aggregates within one of the following tolerances: ±2.0% of the required weights; ±1.0% of the required intermediate and final cumulative weights in aggr egate batchers; or ±0.2% of the scale capacity for intermediate weights below 15% of the scale capacity and for final cumulative weights, 30% below scale capacity.
c.Water . Provide water within ±1.5% of the required quantity, or ±1.0 gallon, whichever is greater .
d.Admixtures . Provide admixtures within ±3% of the required quantity or plus or minus the minimum dosage rate per 100 pounds of cementitious material, whichever is greater.
3.Capacity . Provide weighing and batching equipment capable of weighing, in a single weighing, the quantity of each material required to complete the final batch unless the plant is equipped to weigh the materials using one of the following methods:
a.A device that automatically cycles to provide the required number of increments; or MDOT Standard Specifications for Construction Section 1001
10-5 b. An automatic recording device that provides a permanent record of
the quantity of cement, aggregate, and water measured in each batch.
4.Ticketing System and Weekly Summary . Provide a computer -generated ticket with the following information for each batch:
a.Name of concrete producer;
b.Plant designation where batched;
c.Ticket serial number;
d.Truck number or designation;
e.Name of Contractor;
f.Michigan Department of Transporation ( MDOT ) job number;
g.MDOT grade of concrete;
h.Cubic yards of concrete;
i.Delivery date;
j.Batch loading time;
k.Maximum allowable on-site addition of water;
l.Extra water added on site; and
m.Contractor ’s signature or initials. Provide a space on each ticket for the Engineer to sign. If producing concrete for more than one contract, the concrete producer must include a signed certification statement on each delivery ticket stating that all concrete materials have been tested and approved or certified as meeting Department specifications. If producing concrete at a dedicated batch plant for only one paving contract, the Department does not require the Engineer ’s signature or the concrete batch plant ’s certification statement on each delivery ticket . The Department requires one signature for the daily production accompanied by the concrete batch plant ’s daily summary of concrete production. Provide an automated printout of target and actual batch weights with each delivery ticket . If target and actual batch weight information is computer g enerated on a separate document, include the serial number of the corresponding delivery ticket or other means of cross reference. Attach the automated printout of target and actual batch MDOT Standard Specifications for Construction Section 1001
10-6 weights to the corresponding delivery ticket . Collect tickets
accomp anying loads of concrete and provide them to the Engineer. Provide a sequentially numbered weekly certification report summarizing daily batching operations with shipments identified by contract to the MDOT region materials staff for contracts in their respective region.
B.Non-Certified Batching Plants. Provide automatic cement and aggregate batchers.
1.Weighing and Batching Equipment . Provide weighing and batching equipment capable of weighing, in a single measurement, the quantity of each material required to produce proportioned concrete unless the plant is equipped to weigh materials using one of the following methods:
a.A device that automatically cycles to provide the required number of increments for a batch; or
b.A Department -approved automatic recording device that shows the number of increments placed in each batch. With either method, make batch increments of equal size unless the weighing equipment automatically meets the requirements specified in subsection 1001.03.A.3 for varying batch sizes. Weigh cement and aggregates on separate scales in separate weigh hoppers except in plants equipped to weigh cement cumulatively with aggregates . In plants equipped to weigh cement cumulatively with aggregates, first weigh cement in an enclosed compartme nt of a single weigh hopper . If weighing cement cumulatively with aggregates, conform to the batching tolerances specified in subsection 1001.03.A.2. Provide cement and aggregate in accordance with subsection 1001.03.A.2, except provide cement within 1 % of the cement batch weight . Provide aggregates within 1% of the final cumulative weights, or 94 pounds, whichever is less.
2.Bins and Hoppers . Provide the following:
a.Equipment to load aggregate bins capable of transporting and discharging the aggregate into the bins without spilling into other stockpiles, bins, or compartments;
b.Weathertight bins for each cementitious material;
c.Weighing hoppers of a size and shape capable of holding the material without leaking, supported entirely on the scales; MDOT Standard Specifications for Construction Section 1001
10-7 d. Hoppers and appurtenances designed and constructed to prevent
loss of material during weighing and discharge; and
e.Protection for the material against loss or damage while transferring from the weigh hoppers to the mixer.
3.Scales. Enlist the services of a Michigan Registere d Service Agency to certify the calibration and working order of the weighing system . Display current inspection reports certifying that scales and volumetric batching devices meet the required tolerance at each plant facility . Send current copies of the inspection reports to the Engineer prior to production and thereafter at intervals no longer than 6 months .
4.Automatic Controls . Provide automatic controls for batching equipment with individual starting mechanisms for each material or a single starting mechanism that when actuated, controls all functions of the weighing and metering operations for the materials . For each material weighed, ensure placement of the required weight in the weigh hopper and that the scale indicator balances within the required tolerances for at least 1 second before continuing succeeding operations. Equip the automatic control for each batching scale system with a device for stopping the automatic cycle in the underweight and overweight check positions for each material. Electrically operate and interlock automatic batchers to provide the following controls for each material weighed:
a.Interlock the hopp er inlet mec hanism to prevent opening if the disch arge gate is ope n; and
b.Interlock the hopp er discharge mechani sm to prevent t he following: Opening while filling the hopper; Opening before the full batch is in the hopper and the scale is balanced; Opening if the batch in the hopper is overweight or underweight by more than the required tolerances; and Closing, locking, and starting the next batch before emptying the hopper to less than 1% of the batch weight for the scale. Do not allow the sensing mechanism of the automatic control system to exert a force on the scale-weighing mechanism or indicating mechanism that is within the weighing range of the indicator. MDOT Standard Specifications for Construction Section 1001
10-8 Equip each dial -scale system with a removable dial puller that
inspectors can attach to the dial lever system to check the automatic control system settings by moving the dial smoothly and slowly through its range. Provide weighing systems equipped with load cells and a device capable of simulating load conditions to enable verification of proportioning setpoints and interlocking tolerances for each material . Equip the device with ranges or adjustments to enable a display of each consecutive value of digital indication, held for the time necessary for inspection. Ensure that the plant operator completes the automatic control system checkout procedure periodically, as requested by the Engineer.
5.Dispensers an d Controls for Liquid Admixtures . Provide dispensers capable of measuring the admixture volumetrically . Ensure that batching controls are clearly visible to allow the operator to monitor the accuracy of the admixture delivery . Start the admixture dispenser system using the single starting mechanism for the entire batching system or for one of the primary materials . Introduce the admixture into the sand, the water line, or directly into the mixing drum. Use a separate dispenser for each admixture. If using m ore than one admixture, avoid intermixing admixtures before introduction into the batch by dispensing admixtures as follows:
a.Dispense into different portions of the sand in the weigh hopper;
b.Dispense into different locations in the water line;
c.Use separate outlets into the sand, the water line, and the mixer drum; or
d.Cycle through a common outlet to dispense only one admixture at a time. Provide a dispenser piping system free of leaks with valves to prevent backflow and siphoning. Provide a dispenser system for admixtures capable of measuring and dispensing the quantity required for each batch. Include a device on the dispensing system showing the flow of admixture or showing whether the admixture is in the dispenser. Provide a dispensing device with an accuracy within 3 % of the required material volume batched or within 1.0 fluid ounce, whichever MDOT Standard Specifications for Construction Section 1001
10-9 is greater . Equip the plant with the calibrated devices to check the
dispensed volume to the required accuracy . Provide batching controls that start the batching operation and stop the flow automatically when the required volume is measured. Ensure that controls show when the batching operation is complete. Interlock the admixture dispenser system with the batching operations to ensure that the dispenser resets to start before charging. Interlock the dispenser to ensure that it does not start the admixture discharge unless the controls are cleared of the prev ious batch with the volumetric devices resetting to start or signaling empty.
6.Water Measuring Equipment . Measure water by volume or weight . If directed by the Engineer, demonstrate the accuracy of water -measuring equipment . Ensure that the water system dis charges the required water into the mixer drum during the first one-third of the required mixing time and stops the flow automatically after discharging the required quantity of water . Provide an indicator to show the quantity of water used in each batch.
7.Mixers. Provide mixers meeting the requirements of this subsection. Ensure that mixers combine the aggregates, cementitious materials, water, and admixtures and discharge the mixture without segregation. Provide central batch type mixers with a timing devi ce that automatically locks the discharge mechanism during mixing and releases at the end of the mixing period. Provide a mixer capable of mixing the entire volume of batched material in one operation. Provide revolving drum truck mixers in good condition. Ensure that mix materials, including water, do not leak or spill from the time of charging until discharged. Equip the mixer with a functioning revolution counter to indicate the number of revolutions of the drum . Use truck mixers capable of removing wash water collected in the mixer drum. Ensure that mixers have an attached metal plate showing the following information:
a.Serial number;
b.Maximum mixing capacity in volume of mixed concrete;
c.Mixing speed of the drum; and
d.The maximum agitating capacit y in volume of mixed concrete or on the truck mixers and agitators, the agitating speed of the drum or blades. MDOT Standard Specifications for Construction Section 1001
10-10 8. Concrete Hauling Units . Provide hauling units capable of delivering
concrete in a non-segregated condition. Maintain equipment in good condition. Ensure that mix materials, including water, do not leak or spill from the time of loading until discharged.
9.Continuous Batching and Mixing . Provide continuous batching and mixing equipment meeting the requirements of ASTM C685/C685M. Use only co ntinuous batching and mixing equipment for proportioning latex modified concrete (LMC) or prepackaged hydraulic fast set patching mixtures.
10.Inspector Facilities. Provide space for the inspector to observe batching operations, and when requested by the Engi neer, provide desk space in commercial plants for the inspector ’s use. If the contract requires determinin g the water -to-cementitious -material ratio, provide sample-drying equipment, work, and storage areas for performing moisture tests and storing equipment.
C.Waiver of NRMCA Certification and/or Automation Requirements . If no fully automated certified facility is located within 25 miles of the project, the Engineer may waive certification, automation requirements, or both.
1.Waiver of Certification . The Engineer may allow the use of non-certified automated plants if no fully automated certified facility is located within 25 miles of the project . Provide an automated plant that meets the requirements of subsection 1001.03.B.
2.Waiver of Automation and Certificati on. The Engineer may allow the use of non- certified, manual plants if no automated plant with a batching system meeting the requirements of subsection 1001.03.B is located within 25 miles of the project. If no automatic plant is located within 25 miles of the project, the Engineer will not require the following devices specified in subsection 1001.03.B:
a.Automatic incremental batch cycling devices;
b.Interlocking devices for cement and aggregate;
c.Electrical tolerance indicator devices; and
d.Automatic dispensers for admixtures.
D.Providing and Handling Materials
1.Aggregates. Provide, stockpile, and handle aggregates to minimize segregation. Place each aggregate source and type in a separate bin or stockpile . Do not intermix aggregate sources . Provide firm, level MDOT Standard Specifications for Construction Section 1001
10-11 ground for stockpiles and clean the area of deleterious material before
importing aggregates . Do not use the bottom 12 inches of the stockpile if the stockpile areas are not paved. Do not use lumps of frozen aggregate. Use appropriate equipment and stockpile management procedures to ensure that the aggregates are maintained within specifications. Maintain a uniform aggregate moisture content, with no evidence of surplus water, during each day of concrete production. Keep stockpiles of highly absorpti ve aggregates at a uniform and well-saturated condition using the methods specified in the Department -approved Contractor QC plan for concrete. Store aggregates for Department work in piles or bins separate from aggregates for other work . If the aggregate consists of a blend of at least two gradations, stockpile each gradation separately.
2.Cementitious Material . Store cementitious material provided in bulk form in separate weatherproof bins . Do not use wet or contaminated material. Before refilling bins with new material of a different type or source, empty bins to a quantity less than the quantity necessary for two concrete batches. Changes in cementitious material sources require a new mix design and accompanying j ob mix formula (JMF). If requested by the E ngineer, provide a copy of the shipment notice showing the quantity of each cementitious material for each shipment and certification that the material meets Department specifications.
3.Chemical Admixtures. Handle, store, and protect chemical admixtures in accordance with the manufacturer ’s recommendations.
E.Mixing Concrete
1.General . Produce and deliver ready -mixed concrete as central -mixed or truck-mixed concrete. The Department considers central -mixed concrete completely mixed in a central mixer and transported to the project in a truck agitator, truck mixer, or Department -approved non-agitating equipment . The Department considers truck -mixed concrete completely mixed at the plant site in a truck mixer with a functioning revolution counter. Provide communication service from the project to the batching plant and make the service available to the Engineer during concreting operations. MDOT Standard Specifications for Construction Section 1001
10-12 Empty the mixer drum completely after each batch and before
recharging. Do not exceed the capacity of the mixer shown on the metal plate attached to the mixer . For agitating units and truck mixers used to transport central -mixed concrete, do not exceed the manufacturer ’s recommended batch size for the maximum agitating capacity of the equipment.
2.Batch Mixing . Rotate t he drum or blades at the speeds recommended by the manufacturer and shown on the metal plate attached to the mixer . Measure mixing time from the time all cementitious materials and aggregates are in the mixer until the start of concrete discharge. For mult i-compartment mixers, the mixing time includes the transfer time between drums . Charge the ingredients into the mixer so some water enters before the cementitious materials and aggregate and all the water enters the drum before one-third of the required mi xing time elapses.
a.Central Mixed Concrete. Mix each batch of central mixed concrete for 45 seconds for turbine mixers and 60 seconds for revolving drum and pugmill mixers . For revolving drum and pugmill mixers with a capacity of 1 cubic yard or less, mix f or at least 90 seconds.
b.Truck Mixed Concrete. Mix each batch of truck mixed concrete for more than 70 revolutions at mixing speed.
3.Elapsed Time. Do not exceed the time limits specified in Table 1001-1 from the time of charging the mixer to complete concrete discharge. Table 1001- 1: Time Between Charging Mixer and Placing Concrete Type of Unit Concrete Temperature (ASTM C1064/C1064M) <65°F 65–85°F >85°F Time Between Charging Mixer and Placing Concrete (minutes) Open -top trucks(a) 60 45 30 Open -top agitating units(a) 60 60 30 Closed -top agitating units and truck mixers 90 60 45 Truck mixers and closed -top agitating units with concrete -containing r etarding admixture(b) 120 90 70
a.Not allowed for structural concrete.
b.Superstructure concrete must meet the time limits for closed -top agitating units and truck mixers. MDOT Standard Specifications for Construction Section 1001
10-13 Charging begins when the cementitious materials contact the mixing
water or damp aggregates. For agitating units and truck mixers, if the time from charging the mixer to complete discharge may exceed 30 minutes, agitate the concrete continuously.
4.Additional Water at Placement Site . The QC Administrator may add water to concrete transported in truck mixers or agitators once prior to discharge or placement . The one-time addition of water is permitted to consist of one or more increments only if needed for the concrete to achieve the slump specified in the approved mix design and the batch in the truck mixer or agitator does not exceed the rated mix ing capacity . Add t he final increment of water to achieve the slump specified no later than 15 minutes after the first water addition. Do not add more water than specified in the Department -approved concrete mix design, based on the maximum water content, as defined on the approved JMF, and maximum water -to-cementitious -material ratio. After adding water, provide at least 30 revolutions of the truck mixer drum at mixing speed before discharging concrete. Complete additional mixing at the project within the maximum time specified in subsection 1001.03.E.3. Document water added after batching and the resulting water -to-cementitious -material ratio. Provide the information to the Engineer daily . Do not add water to the concrete during or after discharge or placement . Do not add water for the purpose of retempering the concrete. Do not add water in truck chutes or pump or slipform hoppers beyond the minimum necessary to wet the surfaces for lubrication.
5.Concrete Temperature Requirements. Produce concrete that will ensure that at the time of concrete placement, the concrete temperature will be from 45°F to 90°F. If heating concrete constituents, heat the water, the aggregates, or both to meet the minimum required placement temperature. Do not heat aggregates to more than 150°F . Do not exceed a plastic concrete temperature of 80°F except if placing concrete in insulated forms . Do not exceed a plastic concrete temperature of 70°F if placing concrete in insulated forms . Mix the water with the aggregates before adding the cementitious materials. Use aggregates free of ice and frozen lumps at time of batching. Heat aggregates in stockpiles or bins using steam or hot water coils or live steam or by indirect hot air . Do not use direct flame to heat coarse aggregate. During batching operations, compensate for accumulated MDOT Standard Specifications for Construction Section 1001
10-14 condensation from heating to maintain the slump within the required
limits 1001.04. Measurement and Payment The cost of providing PCC pavement and structural mixtures is included in unit prices for related pay items.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 1039–1052 of 1,146.