Category:501 Concrete - Revision history

Hoskir: /* 501.1.10.1 General */ updated per RR3828

2024-01-29T15:35:03Z

501.1.10.1 General: updated per RR3828

← Older revision		Revision as of 10:35, 29 January 2024
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	===501.1.10 2AA Sheet For Concrete Pavement===		===501.1.10 2AA Sheet For Concrete Pavement===
	====501.1.10.1 General====		====501.1.10.1 General====
	The 2AA Sheet is a summary and graphic record of the design, typical section, materials, and methods used in the construction of the base, surfacing, and shoulders of a portland cement concrete paving project. ~~It will include data on~~ the ~~throughway at all interchanges and underpasses. It~~ is ~~not~~ necessary ~~to prepare a 2AA Sheet for pavement in traffic interchanges~~ or ~~underpasses constructed in isolated sections 750 feet or less~~ in length ~~or isolated areas within the primary travelway of 1000 S.Y or less~~. The blank 2AA Sheet can be located ~~on Micro Station Directory. t:\standard\wsmod\design\seed_i\i_2aa-2d~~.~~dgn~~		The 2AA Sheet is a summary and graphic record of the design, typical section, materials, and methods used in the construction of the base, surfacing, and shoulders of a portland cement concrete paving project. This record is to be produced by the paving inspector, but is only necessary on projects that have one or more mainline concrete paving segments that exceed one-half mile in length. The blank 2AA Sheet can be located in the OpenRoads Designer CADD Standards.

	Information provided on this sheet is valuable for future investigations and often is not available from any other source. Information on the paving work is to be recorded by daily entries made by the plant inspector on a 2AA Sheet, kept as a work sheet in the laboratory during the paving. This requires close liaison between the plant inspector and the field inspection force. If the slab inspector notes any changes in construction details or other data of the type required on the 2AA Sheet, the slab inspector should immediately notify the plant inspector of the change and the station where it occurred. The plant inspector should promptly plot it on the 2AA work sheet. Inspectors on base and shoulder construction should provide data in a like manner so that a complete, accurate record can be kept up-to-date.		Information provided on this sheet is valuable for future investigations and often is not available from any other source. Information on the paving work is to be recorded by daily entries made by the plant inspector on a 2AA Sheet, kept as a work sheet in the laboratory during the paving. This requires close liaison between the plant inspector and the field inspection force. If the slab inspector notes any changes in construction details or other data of the type required on the 2AA Sheet, the slab inspector should immediately notify the plant inspector of the change and the station where it occurred. The plant inspector should promptly plot it on the 2AA work sheet. Inspectors on base and shoulder construction should provide data in a like manner so that a complete, accurate record can be kept up-to-date.

Kleins1: Updated per COCM Revision Req. #3478

2022-07-25T15:45:19Z

Updated per COCM Revision Req. #3478

Show changes

Smithk: Per CM, revision reflects AASHTO's renaming of test method T23 to R100

2021-11-09T21:10:12Z

Per CM, revision reflects AASHTO's renaming of test method T23 to R100

← Older revision		Revision as of 16:10, 9 November 2021
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	Each set of compressive test specimens for standard cure consists of two 6x12 cylinders or three 4x8 cylinders.		Each set of compressive test specimens for standard cure consists of two 6x12 cylinders or three 4x8 cylinders.

	Standard Cure specimens shall be cured in accordance with AASHTO ~~T23~~ (ASTM C31) for initial and final curing.		Standard Cure specimens shall be cured in accordance with AASHTO R100 (ASTM C31) for initial and final curing.

	'''Standard Cure – Initial'''		'''Standard Cure – Initial'''
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	:4) Form removal.		:4) Form removal.

	Field curing shall be in accordance with AASHTO ~~T23~~ (ASTM C 31). Store cylinders in or on the structure as near as practical to the represented concrete. Protect all surfaces of the cylinders from the elements and ensure a temperature and moisture environment similar to the formed work. To meet these conditions specimens made for the purpose of determining when a structure is capable of being put in service shall be removed from the molds at the time of removal of form work.		Field curing shall be in accordance with AASHTO R100 (ASTM C 31). Store cylinders in or on the structure as near as practical to the represented concrete. Protect all surfaces of the cylinders from the elements and ensure a temperature and moisture environment similar to the formed work. To meet these conditions specimens made for the purpose of determining when a structure is capable of being put in service shall be removed from the molds at the time of removal of form work.

	Compressive test specimens for field cures may consist of one or more sets for either 6x12 cylinders or 4x8 cylinders.		Compressive test specimens for field cures may consist of one or more sets for either 6x12 cylinders or 4x8 cylinders.

Smithk: Updated CM website link (for increased security)

2021-10-22T15:09:53Z

Updated CM website link (for increased security)

← Older revision		Revision as of 10:09, 22 October 2021
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	:(k) Batch weight of water.		:(k) Batch weight of water.

	To aid the contractor in submitting concrete mix designs to the district for approval, there is a [~~http~~://epg.modot.~~mo.gov~~/forms/CM/Concrete%20Mix%20Design%20Submittal%20Form.xls concrete mix design submittal form] which may be used by the contractor. This form contains all of the required information needed for the mix design to be evaluated. This form can be accessed by MoDOT personnel in SharePoint at [http://sp/sites/CM/FormServerTemplates/Concrete%20Mix%20Design%20Submittal%20Form.xls Concrete Mix Design Submittal Form].		To aid the contractor in submitting concrete mix designs to the district for approval, there is a [https://epg.modot.org/forms/CM/Concrete%20Mix%20Design%20Submittal%20Form.xls concrete mix design submittal form] which may be used by the contractor. This form contains all of the required information needed for the mix design to be evaluated. This form can be accessed by MoDOT personnel in SharePoint at [http://sp/sites/CM/FormServerTemplates/Concrete%20Mix%20Design%20Submittal%20Form.xls Concrete Mix Design Submittal Form].

	===501.2.4 District Procedures===		===501.2.4 District Procedures===

Smithk at 17:11, 24 September 2021

2021-09-24T17:11:58Z

Smithk: /* 501.2.3 Mix Design Information */ Per CM, replaced archaic V:drive info with eProject info

2021-09-24T17:08:28Z

501.2.3 Mix Design Information: Per CM, replaced archaic V:drive info with eProject info

← Older revision		Revision as of 12:08, 24 September 2021
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	:(k) Batch weight of water.		:(k) Batch weight of water.

	To aid the contractor in submitting concrete mix designs to the district for approval, there is a [http://modot.mo.gov/~~business~~/~~materials~~/Concrete%20Mix%20Design%20Submittal%20Form.xls concrete mix design submittal form] which may be used by the contractor. This form contains all of the required information needed for the mix design to be evaluated. This form can be accessed by MoDOT personnel at V:~~\Reports Master SpreadSheets\~~Concrete Mix Design Submittal Form.		To aid the contractor in submitting concrete mix designs to the district for approval, there is a [http://epg.modot.mo.gov/forms/CM/Concrete%20Mix%20Design%20Submittal%20Form.xls concrete mix design submittal form] which may be used by the contractor. This form contains all of the required information needed for the mix design to be evaluated. This form can be accessed by MoDOT personnel in SharePoint at [http://sp/sites/CM/FormServerTemplates/Concrete%20Mix%20Design%20Submittal%20Form.xls Concrete Mix Design Submittal Form].

	===501.2.4 District Procedures===		===501.2.4 District Procedures===

Smithk: /* 501.1.3.5.2 QC/QA Testing Requirements */ Per CM, removed archaic SiteManager info and replaced with AASHTOWARE info

2021-09-14T13:10:13Z

501.1.3.5.2 QC/QA Testing Requirements: Per CM, removed archaic SiteManager info and replaced with AASHTOWARE info

← Older revision		Revision as of 08:10, 14 September 2021
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	'''Test Procedures'''		'''Test Procedures'''

	A calibrated testing machine must be used by a certified technician. The [[~~media~~:~~Concrete Cylinder~~ Sample ~~Sent to Central Lab.doc~~\|~~AASHTOWare sample record]] [[image:bulldozer.jpg\|20px~~]] must be completed documenting the testing. Testing is to be done in the hydraulically operated compressive testing machine. If there is doubt as to the 28-day strength of the cylinder, relative to the working capability of the available testing machine, send the cylinders to the Central Laboratory. All specimens are to be loaded to failure.		A calibrated testing machine must be used by a certified technician. The [[:Category:101 Standard Forms#Sample Record, General\|AWP MA Sample Record, General]] must be completed documenting the testing. Testing is to be done in the hydraulically operated compressive testing machine. If there is doubt as to the 28-day strength of the cylinder, relative to the working capability of the available testing machine, send the cylinders to the Central Laboratory. All specimens are to be loaded to failure.

	All cylinders are to be tested using a neoprene cap in a steel extrusion controller placed on each end of the cylinder. The neoprene caps have 6 1/8 in. diameters and are 1/2 in. thick. The caps are made from neoprene and no substitution of material or cap is to be made. A 50 durometer neoprene cap is used for concrete with a cement factor of less than 7.5 sacks per yard. Otherwise, a 60 durometer neoprene cap is used. The caps should be replaced if worn or after a maximum of 100 cylinder breaks.		All cylinders are to be tested using a neoprene cap in a steel extrusion controller placed on each end of the cylinder. The neoprene caps have 6 1/8 in. diameters and are 1/2 in. thick. The caps are made from neoprene and no substitution of material or cap is to be made. A 50 durometer neoprene cap is used for concrete with a cement factor of less than 7.5 sacks per yard. Otherwise, a 60 durometer neoprene cap is used. The caps should be replaced if worn or after a maximum of 100 cylinder breaks.

Smithk at 17:10, 17 August 2021

2021-08-17T17:10:21Z

Smithk: /* 501.1 Construction Inspection for Sec 501 */ Per CM, clarification of curing and testing procedures for cores and cylinders in projects with paving and structures.

2021-03-26T18:33:23Z

501.1 Construction Inspection for Sec 501: Per CM, clarification of curing and testing procedures for cores and cylinders in projects with paving and structures.

← Older revision		Revision as of 13:33, 26 March 2021
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	Curing of compressive specimens will depend on whether they are for standard cure or field cure.		Curing of compressive specimens will depend on whether they are for standard cure or field cure.

	'''Standard Cure''' is ~~defined as~~ 1) ~~specified~~ strength for 28-day testing; 2) Check of mixture proportions or design strength; 3) Quality control (i.e. monitoring mix variability) or 4) Maturity meter curve.		'''Standard Cure''' is used for the following purposes:
			:1) Specified strength for 28-day testing
			:2) Check of mixture proportions or design strength
			:3) Quality control (i.e. monitoring mix variability)
			:4) Maturity meter curve.

	Standard curing involves two phases of curing: initial and final.		Standard curing involves two phases of curing: initial and final.

	Each set of compressive test specimens for standard cure consists of two 6x12 cylinders or three 4x8 cylinders.		Each set of compressive test specimens for standard cure consists of two 6x12 cylinders or three 4x8 cylinders.

	Standard Cure specimens shall be cured in accordance with AASHTO T23 (ASTM C31) for initial and final curing.		Standard Cure specimens shall be cured in accordance with AASHTO T23 (ASTM C31) for initial and final curing.

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	:Specimens may be transported to the Central Laboratory for final curing. To transport, after the initial cure period, the specimen shall be removed from the mold and placed in a plastic bag to maintain free moisture during shipping. Specimens should not be transported to begin final cure until at least 8 hours after final set. During transporting, use suitable material to prevent damage from jarring and use suitable insulation material during cold weather.		:Specimens may be transported to the Central Laboratory for final curing. To transport, after the initial cure period, the specimen shall be removed from the mold and placed in a plastic bag to maintain free moisture during shipping. Specimens should not be transported to begin final cure until at least 8 hours after final set. During transporting, use suitable material to prevent damage from jarring and use suitable insulation material during cold weather.

	:Show shipper's name and address on the outside of the box. The box comes with the address of Central Laboratory printed on the side and a preprinted form that provides basic information about the cylinders. If the box does not have the form preprinted, contact the Central Laboratory for copies of the self stick form. ~~SiteManager~~ Sample ID number should be written on the side of cylinders or cylinder molds.		:Show shipper's name and address on the outside of the box. The box comes with the address of Central Laboratory printed on the side and a preprinted form that provides basic information about the cylinders. If the box does not have the form preprinted, contact the Central Laboratory for copies of the self stick form. AASHTOWare Project Sample ID number should be written on the side of cylinders or cylinder molds.

	:Necessary boxes, cardboard liners, polyethylene bags, wire ties and rolls of strapping tape are stock items available by requisition.		:Necessary boxes, cardboard liners, polyethylene bags, wire ties and rolls of strapping tape are stock items available by requisition.
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	'''Field Curing'''		'''Field Curing'''

	'''Field cure''' is ~~defined as~~ 1) Opening to traffic strength or staged construction; 2) Comparison with test results of standard cure to in place methods, such as maturity method verification; 3) Adequacy of curing and protection of concrete in the structure, such as cold weather placement or 4) Form removal.		'''Field cure''' is used for the following purposes:
			:1) Opening to traffic strength or staged construction
			:2) Comparison with test results of standard cure to in place methods, such as maturity method verification
			:3) Adequacy of curing and protection of concrete in the structure, such as cold weather placement
			:4) Form removal.

	Field curing shall be in accordance with AASHTO T23 (ASTM C 31). Store cylinders in or on the structure as near as practical to the represented concrete. Protect all surfaces of the cylinders from the elements, and ensure a temperature and moisture environment similar to the formed work. To meet these conditions specimens made for the purpose of determining when a structure is capable of being put in service shall be removed from the molds at the time of removal of form work.		Field curing shall be in accordance with AASHTO T23 (ASTM C 31). Store cylinders in or on the structure as near as practical to the represented concrete. Protect all surfaces of the cylinders from the elements and ensure a temperature and moisture environment similar to the formed work. To meet these conditions specimens made for the purpose of determining when a structure is capable of being put in service shall be removed from the molds at the time of removal of form work.

	Compressive test specimens for field cures may consist of one or more sets for either 6x12 cylinders or 4x8 cylinders.		Compressive test specimens for field cures may consist of one or more sets for either 6x12 cylinders or 4x8 cylinders.
	Specimens prepared to determine when forms may be removed will be cured as described in above except for bridge decks or heated concrete. Specimens representing bridge decks are to be cured on the deck under wet mats until the cylinders are to be broken or wet curing is discontinued. If cylinders remain after wet curing has ended, they shall be cured in plastic molds under field conditions until they are to be broken.

	Specimens representing heated concrete are to be left in the enclosure subject to the same protection as concrete they represent until they are to be broken. Cylinders should be ~~left~~ in molds and covered with wet burlap for 48 hours. ~~If cylinders remain~~ after the heating period has ended ~~they~~ shall ~~be cured~~ in plastic molds under field conditions until they are to be broken.		Specimens prepared to determine when forms may be removed will be cured as described above except for bridge decks or heated concrete.
			:- Specimens representing bridge decks are to be cured in plastic molds on the deck under wet mats until the cylinders are to be broken or wet curing is discontinued. If cylinders remain after wet curing has ended, they shall remain in plastic molds under field conditions until they are to be broken.
			:- Specimens representing heated concrete are to be left in the enclosure subject to the same protection as concrete they represent until they are to be broken. Cylinders should be in plastic molds and covered with wet burlap for 48 hours. Cylinders left after the heating period has ended shall remain in plastic molds under field conditions until they are to be broken.

	Curing of bridge decks shall be in accordance with Standard Specification 704, wet curing shall be maintained for 7 days '''and''' until the concrete has reached a minimum of 3000 psi.		Curing of bridge decks shall be in accordance with Standard Specification 704, wet curing shall be maintained for 7 days '''and''' until the concrete has reached a minimum of 3000 psi.

	=====501.1.3.5.2 Testing Requirements=====		=====501.1.3.5.2 QC/QA Testing Requirements=====

	'''Structures'''		'''Structures'''

	A set of standard cure specimens ~~should~~ be prepared and tested to verify the compressive strength of each mix design during initial production and for every 500 cubic yards thereafter. Any change in mix design shall also require ~~Standard Cure~~ verification. Verification of mix design by ~~Standard Cured~~ specimens may represent multiple projects.		A set of QA standard cure specimens shall be prepared and tested to verify the 28-day compressive strength of each mix design during initial production and for every 500 cubic yards thereafter or once for every project with less than 500 cubic yards. Any change in mix design shall also require standard cure verification. Verification of mix design by standard cure specimens may represent multiple concurrent projects using the same mix design. The MoDOT inspector should also prepare QA field cure specimens, for every 500 cubic yards or once for every project with less than 500 cubic yards, to verify the contractor field cure strength results.

	~~Field~~ cure specimens ~~should~~ be prepared for each structural pour and for every 100 cubic yards where it is necessary to control construction processes such as form removal, discontinuance of heating or wet curing, and acceptance		QC field cure specimens shall be prepared for each structural pour and for every 100 cubic yards where it is necessary to control construction processes such as falsework or form removal, discontinuance of heating or wet curing, opening to traffic, and acceptance. The contractor may stop testing QC field cure specimens, representing a construction process, once the minimum strength requirement has been met. The contractor may cast as many specimens as desired to verify minimum strength. The contractor is not required to arbitrarily test at the completion of 28 days, if minimum strength has been met at an earlier time for a particular construction process.

	'''Paving'''		'''Paving'''

	QC/QA field core specimens ~~are~~ used for acceptance for ~~paving projects~~. ~~Under normal circumstances~~ QLA and PWL calculations ~~are used~~ to determine payment. Cylinder specimens may be made at any time for informational purposes.		A set of QA standard cure specimens shall be prepared and tested to verify the 28-day compressive strength of each mix design during initial production for any size paving project.

			Both QC and QA field core specimens shall be used for acceptance of any paving project greater than 7500 sq. yd., except as noted for phased construction, below. Since these cores are used in QLA and PWL calculations to determine payment, they must be tested at 28 days. Cylinder specimens may be made at any time for informational purposes.

			For paving projects with small quantities (< 7500 sq. yd.), or with larger quantities of phased construction exempted from QLA and PWL calculations, either a set of QC standard cure cylinder specimens or QC field core specimens shall be tested for compressive strength for every 2000 sq. yd. Testing of QC cores/cylinders may discontinue once opening strength and/or design strength has been achieved.

			'''Section 608 Items'''

			A set of QA standard cure specimens shall be prepared and tested to verify the 28-day compressive strength of each mix design during initial production for any size project with sidewalk, median, paved approaches, etc. Either a set of QA standard cure cylinder specimens or QA field core specimens shall be tested for compressive strength for every 500 cubic yards, or once for every project with less than 500 cubic yards to verify the contractor field cure strength results.

	~~For small quantities (< 7500 sq. yd.) or larger quantities of phased construction exempted from QLA and PWL,~~ a set of standard cure specimens ~~should~~ be tested for compressive strength ~~from the first pour~~ of ~~each type of mix used~~.		Either a set of QC standard cure cylinder specimens or QC field core specimens shall be tested for compressive strength for every 100 cu yd. Testing of QC cores/cylinders may discontinue once opening strength and/or design strength has been achieved.

	'''Test Procedures'''		'''Test Procedures'''

	A calibrated testing machine must be used by a certified technician. The [[media:Concrete Cylinder Sample Sent to Central Lab.doc\|~~SiteManager~~ sample record]] [[image:bulldozer.jpg\|20px]] must be completed documenting the testing. Testing is to be done in the hydraulically operated compressive testing machine. If there is doubt as to the 28-day strength of the cylinder, relative to the working capability of the available testing machine, send the cylinders to the Central Laboratory. All specimens are to be loaded to failure.		A calibrated testing machine must be used by a certified technician. The [[media:Concrete Cylinder Sample Sent to Central Lab.doc\|AASHTOWare sample record]] [[image:bulldozer.jpg\|20px]] must be completed documenting the testing. Testing is to be done in the hydraulically operated compressive testing machine. If there is doubt as to the 28-day strength of the cylinder, relative to the working capability of the available testing machine, send the cylinders to the Central Laboratory. All specimens are to be loaded to failure.

	All cylinders are to be tested using a neoprene cap in a steel extrusion controller placed on each end of the cylinder. The neoprene caps have 6 1/8 in. diameters and are 1/2 in. thick. The caps are made from neoprene and no substitution of material or cap is to be made. A 50 durometer neoprene cap is used for concrete with a cement factor of less than 7.5 sacks per yard. Otherwise, a 60 durometer neoprene cap is used. The caps should be replaced if worn or after a maximum of 100 cylinder breaks.		All cylinders are to be tested using a neoprene cap in a steel extrusion controller placed on each end of the cylinder. The neoprene caps have 6 1/8 in. diameters and are 1/2 in. thick. The caps are made from neoprene and no substitution of material or cap is to be made. A 50 durometer neoprene cap is used for concrete with a cement factor of less than 7.5 sacks per yard. Otherwise, a 60 durometer neoprene cap is used. The caps should be replaced if worn or after a maximum of 100 cylinder breaks.
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	On digital readout machines, total load is captured automatically. On dial readout machines, although the red needle is supposed to indicate total load, it should be watched carefully to be sure it does not spring back at failure of the specimen. As soon as the specimen fails, the pressure should be released allowing the upper block to return to the unloaded position.		On digital readout machines, total load is captured automatically. On dial readout machines, although the red needle is supposed to indicate total load, it should be watched carefully to be sure it does not spring back at failure of the specimen. As soon as the specimen fails, the pressure should be released allowing the upper block to return to the unloaded position.

	All test data shall be recorded in ~~SiteManager~~. Results of the tests are to be reported to the nearest 10 psi.		All test data shall be recorded in AASHTOWare Project. Results of the tests are to be reported to the nearest 10 psi.

	===501.1.4 Consistency (Sec 501.5)===		===501.1.4 Consistency (Sec 501.5)===

Smithk: /* 501.1.1 Material (Sec 501.2) */ Per CM, updated "Site Manger" to "AWP"

2020-11-12T20:55:12Z

501.1.1 Material (Sec 501.2): Per CM, updated "Site Manger" to "AWP"

← Older revision		Revision as of 15:55, 12 November 2020
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	The proportioning plant inspector must be certain that all materials have been properly		The proportioning plant inspector must be certain that all materials have been properly
	inspected and approved before permitting their use. Cement is normally accompanied by appropriate certification as described in [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=14 Section 1019] of the Standard Specifications. Aggregate suppliers will be designated in ~~Site Manager~~.		inspected and approved before permitting their use. Cement is normally accompanied by appropriate certification as described in [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=14 Section 1019] of the Standard Specifications. Aggregate suppliers will be designated in AWP.

	===501.1.2 Mix Design (Sec 501.3)===		===501.1.2 Mix Design (Sec 501.3)===

← Older revision		Revision as of 12:11, 24 September 2021
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	===501.1.2 Mix Design (Sec 501.3)===		===501.1.2 Mix Design (Sec 501.3)===
	The contractor shall design and submit all concrete mixes to ~~District~~ Materials for review		The contractor shall design and submit all concrete mixes to district Materials for review
	and approval. The mix shall be designed by absolute volume methods or an optimized mix		and approval. The mix shall be designed by absolute volume methods or an optimized mix
	design. Optimized refers to a well graded combined aggregate gradation resulting in lower water		design. Optimized refers to a well graded combined aggregate gradation resulting in lower water
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	===501.2.2 Mix Design Procedures===		===501.2.2 Mix Design Procedures===
	Portland cement concrete mix designs will be reviewed by ~~District~~ Materials for specification compliance. The ~~District~~ will approve concrete mix designs complying with the specifications and meeting the guidelines outlined in this guidance. After reviewing the concrete mix, the ~~District~~ will prepare a letter advising the contractor whether the concrete mix has been approved or rejected. A copy of the approved concrete mix shall be sent to the Materials Field Office (See [[media:501 Format for Concrete Mixes.pdf\|example format]]).		Portland cement concrete mix designs will be reviewed by district Materials for specification compliance. The district will approve concrete mix designs complying with the specifications and meeting the guidelines outlined in this guidance. After reviewing the concrete mix, the district will prepare a letter advising the contractor whether the concrete mix has been approved or rejected. A copy of the approved concrete mix shall be sent to the Materials Field Office (See [[media:501 Format for Concrete Mixes.pdf\|example format]]).

	===501.2.3 Mix Design Information===		===501.2.3 Mix Design Information===
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	===501.2.4 District Procedures===		===501.2.4 District Procedures===
	When a Portland cement concrete mix has been received by the ~~District~~, the ~~District~~ will check the calculations thoroughly and ensure that the materials listed and sieve analysis shown are correct and that the proposed proportions comply with Specifications. It may be necessary for the ~~District~~ to advise the contractor to make adjustments to their mix design in order to comply with the Specifications.		When a Portland cement concrete mix has been received by the district, the district will check the calculations thoroughly and ensure that the materials listed and sieve analysis shown are correct and that the proposed proportions comply with Specifications. It may be necessary for the district to advise the contractor to make adjustments to their mix design in order to comply with the Specifications.

	====501.2.4.1 Portland Cement====		====501.2.4.1 Portland Cement====
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	===501.2.5 Laboratory Mix Verification===		===501.2.5 Laboratory Mix Verification===
	If during the review process the ~~District~~ identifies a concrete mix that needs further evaluation, the concrete mix may be sent to the Materials Field Office for further evaluation and possibly mix verification, if deemed necessary. A copy of the mix design and the contractor’s request letter shall be submitted to the Materials Field Office accompanied by a letter of transmittal outlining the reasons the mix needs further evaluation. When possible, the concrete mix and correspondence should be transmitted electronically. The Materials Field Office e-mail address is MFO.		If during the review process the district identifies a concrete mix that needs further evaluation, the concrete mix may be sent to the Materials Field Office for further evaluation and possibly mix verification, if deemed necessary. A copy of the mix design and the contractor’s request letter shall be submitted to the Materials Field Office accompanied by a letter of transmittal outlining the reasons the mix needs further evaluation. When possible, the concrete mix and correspondence should be transmitted electronically. The Materials Field Office e-mail address is MFO.

	====501.2.5.1 Trial Batch====		====501.2.5.1 Trial Batch====
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	\|'''See also:''' [https://www.modot.org/research-publications Research Publications]		\|'''See also:''' [https://www.modot.org/research-publications Research Publications]
	\|}		\|}
	The use of approved high range water reducers and non-chloride accelerators will be permitted for use in precast concrete having a minimum cement content of 564 pounds and no other specific air or slump mix requirements, if approved by the ~~district~~ Operations Engineer except for concrete pipe. Requests for additives to concrete pipe should be directly to the State Construction and Materials Engineer.		The use of approved high range water reducers and non-chloride accelerators will be permitted for use in precast concrete having a minimum cement content of 564 pounds and no other specific air or slump mix requirements, if approved by the District Operations Engineer except for concrete pipe. Requests for additives to concrete pipe should be directly to the State Construction and Materials Engineer.

	'''501.2.6.1''' The producer shall furnish a mix design to the District Operations Engineer, for approval, which shall indicate the batch weights, including the amount of admixture(s) to be used.		'''501.2.6.1''' The producer shall furnish a mix design to the District Operations Engineer, for approval, which shall indicate the batch weights, including the amount of admixture(s) to be used.
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	'''501.2.6.3''' The accelerators shall be of the non-chloride type.		'''501.2.6.3''' The accelerators shall be of the non-chloride type.

	'''501.2.6.4''' The supplier of the high range water reducer shall furnish for the ~~district~~ Operation Engineer’s file, a certification stating the admixture being furnished is considered to be compatible with the other admixtures (i.e. air entrainment, retarded, accelerator, etc. by brand name) being used in the mixture. Any changes in sources of admixture will require a re-submittal of the certification.		'''501.2.6.4''' The supplier of the high range water reducer shall furnish for the District Operation Engineer’s file, a certification stating the admixture being furnished is considered to be compatible with the other admixtures (i.e. air entrainment, retarded, accelerator, etc. by brand name) being used in the mixture. Any changes in sources of admixture will require a re-submittal of the certification.

	'''501.2.6.5''' A copy of the approval of the mix design using the above admixtures shall be submitted to the State Construction and Materials Engineer.		'''501.2.6.5''' A copy of the approval of the mix design using the above admixtures shall be submitted to the State Construction and Materials Engineer.
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	Class A-1 Concrete was created for prestress work. It provides a smaller aggregate, which is necessary to accommodate the often-minimal clearance between forms and reinforcement, or within the reinforcement cage. It also provides additional cement to accommodate the water demand associated with the smaller rock, and to obtain faster strength gain. Class A-1 Concrete for work other than prestress may be modified as follows:		Class A-1 Concrete was created for prestress work. It provides a smaller aggregate, which is necessary to accommodate the often-minimal clearance between forms and reinforcement, or within the reinforcement cage. It also provides additional cement to accommodate the water demand associated with the smaller rock, and to obtain faster strength gain. Class A-1 Concrete for work other than prestress may be modified as follows:

	'''501.2.7.1''' Gradation D stone may be substituted for Gradation E stone, when the piece being cast does not have clearance problems that might cause Gradation D stone to bridge and cause voids or low density areas within the piece. When the ~~District~~ and the precaster are in agreement on the desirability of the Gradation D substitution, Construction and Materials shall be contacted with the proposal.		'''501.2.7.1''' Gradation D stone may be substituted for Gradation E stone, when the piece being cast does not have clearance problems that might cause Gradation D stone to bridge and cause voids or low density areas within the piece. When the district and the precaster are in agreement on the desirability of the Gradation D substitution, Construction and Materials shall be contacted with the proposal.

	'''501.2.7.2''' Construction and Materials will review the proposal and will approve or disapprove the substitution of Gradation D stone for Gradation E stone in the designated application.		'''501.2.7.2''' Construction and Materials will review the proposal and will approve or disapprove the substitution of Gradation D stone for Gradation E stone in the designated application.
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	===501.2.8 Testing Equipment===		===501.2.8 Testing Equipment===
	All Quality Control (QC) testing shall be performed on QC test equipment. Quality Assurance (QA) testing shall be performed on QA test equipment. QC tests shall not be performed using QA testing equipment and QA tests shall not be performed using QC testing equipment. QA samples may be submitted to the Central Laboratory for testing if the ~~District~~ does not have the necessary testing equipment.		All Quality Control (QC) testing shall be performed on QC test equipment. Quality Assurance (QA) testing shall be performed on QA test equipment. QC tests shall not be performed using QA testing equipment and QA tests shall not be performed using QC testing equipment. QA samples may be submitted to the Central Laboratory for testing if the district does not have the necessary testing equipment.

	===501.2.9 Aluminum Powder===		===501.2.9 Aluminum Powder===

← Older revision		Revision as of 12:10, 17 August 2021
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	Verification of weighing equipment will consist of balancing the scales and then loading the scale to approximately 250 pounds below the scale setting, then adding approximately 500 pounds of standard test weight in not more than 150 pound increments to bring the scale to approximately 250 pounds over the scale setting.		Verification of weighing equipment will consist of balancing the scales and then loading the scale to approximately 250 pounds below the scale setting, then adding approximately 500 pounds of standard test weight in not more than 150 pound increments to bring the scale to approximately 250 pounds over the scale setting.

	These weight intervals for calibration, verification, balance and sensitivity are considered to be the maximum. If difficulty is encountered with the batching operation or if any of the aforementioned checks indicate excessive deviations, the plant should be recalibrated to ~~insure~~ compliance.		These weight intervals for calibration, verification, balance and sensitivity are considered to be the maximum. If difficulty is encountered with the batching operation or if any of the aforementioned checks indicate excessive deviations, the plant should be recalibrated to ensure compliance.

	[http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=8 Sec 502.4.5] of the Standard Specifications sets out certain conditions under which automatic batching equipment must be furnished. In addition to calibration procedures, automatic equipment must be checked for compliance with requirements of Sec 502.4.5 of the Standard Specifications. It is particularly important to ascertain that the discharge		[http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=8 Sec 502.4.5] of the Standard Specifications sets out certain conditions under which automatic batching equipment must be furnished. In addition to calibration procedures, automatic equipment must be checked for compliance with requirements of Sec 502.4.5 of the Standard Specifications. It is particularly important to ascertain that the discharge
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	Calibration of all proportioning devices shall be on a weight basis with the exception of the admixture flow meters which may be calibrated on either a weight or a volume basis.		Calibration of all proportioning devices shall be on a weight basis with the exception of the admixture flow meters which may be calibrated on either a weight or a volume basis.

	The first step in calibrating a volumetric proportioning unit is to determine the exact cement meter count and the corresponding time in seconds, to 0.1 second, for the discharge of one sack or 94 lbs. of cement. Both aggregate bins should be empty and the main conveyor belt should be clean. Check to ~~insure~~ that all bin vibrators and the cement bin aeration system are functioning properly. Set throttle to hold the specified RPM reading on mechanical drive units or advance throttle to the preset stop on hydraulic drive units. Discharge enough cement to ~~insure~~ that the main conveyor belt is fully primed and then reset the cement meter so it reads zero. Discharge approximately 100 pounds of cement into a clean, tared container. Carefully time the run by starting and stopping the stop watch at exactly the same time that the main clutch is engaged and disengaged. Record the actual weight of cement discharged, the cement meter count and the time to the nearest 0.1 second. A minimum of six test runs shall be made. Divide the total meter counts for the six test runs by the total weight of cement discharged and multiply this factor by 94 (the weight of one sack of cement) to determine the meter count to discharge one sack of cement. Likewise, divide the total number of seconds for the six test runs by the total weight of cement discharged and multiply this factor by 94 to determine the time, to the nearest 0.1 second, to discharge one sack of cement.		The first step in calibrating a volumetric proportioning unit is to determine the exact cement meter count and the corresponding time in seconds, to 0.1 second, for the discharge of one sack or 94 lbs. of cement. Both aggregate bins should be empty and the main conveyor belt should be clean. Check to ensure that all bin vibrators and the cement bin aeration system are functioning properly. Set throttle to hold the specified RPM reading on mechanical drive units or advance throttle to the preset stop on hydraulic drive units. Discharge enough cement to ensure that the main conveyor belt is fully primed and then reset the cement meter so it reads zero. Discharge approximately 100 pounds of cement into a clean, tared container. Carefully time the run by starting and stopping the stop watch at exactly the same time that the main clutch is engaged and disengaged. Record the actual weight of cement discharged, the cement meter count and the time to the nearest 0.1 second. A minimum of six test runs shall be made. Divide the total meter counts for the six test runs by the total weight of cement discharged and multiply this factor by 94 (the weight of one sack of cement) to determine the meter count to discharge one sack of cement. Likewise, divide the total number of seconds for the six test runs by the total weight of cement discharged and multiply this factor by 94 to determine the time, to the nearest 0.1 second, to discharge one sack of cement.

	Calibration procedures and calculations for both fine and coarse aggregate are the same. Because the gates on the fine and coarse aggregate bins of a volumetric proportioning unit do not completely close, only one of these materials can be charged into the mixer at any one time during calibration. Assuming that fine aggregate bin is to be calibrated first, fill it at least two-thirds full with sand and make sure the coarse aggregate bin is empty. Check to ~~insure~~ that all bin vibrators are functioning properly and that the Cement Meter-Feeder clutch is disengaged to prevent cement discharge while calibrating the aggregate bins. The operator should set the sand gate control at the approximate setting for the weight desired based on previous experience. Set the throttle as noted above. Discharge and waste enough fine aggregate to ~~insure~~ that the main conveyor belt is fully primed. Discharge approximately 150 to 200 pounds of fine aggregate into a clean, tared container. Carefully time the run by starting and stopping the stop watch exactly when the main clutch is engaged and disengaged. Record the weight of fine aggregate and the actual time to the nearest 0.1 second. Using these two figures and the time determined above, set up a direct proportion to calculate the amount of fine aggregate delivered in the exact length of time it takes to deliver 94 pounds of cement. If the actual quantity delivered is not within the allowable tolerance of the quantity required, adjust the gate control as needed and repeat the above procedure. Several trial runs may be necessary to obtain the correct gate setting. Once this gate setting has been established, at least three runs should be made to verify that it is correct. Empty the fine aggregate bin, charge the coarse aggregate bin and follow the same procedure as above to determine the coarse aggregate gate setting. If several mixes will be used from the same proportioning unit, coarse and fine aggregate bin curves may be plotted using three or more gate settings. The curves should cover the full range of aggregate flow rates anticipated and should be verified within the appropriate tolerances.		Calibration procedures and calculations for both fine and coarse aggregate are the same. Because the gates on the fine and coarse aggregate bins of a volumetric proportioning unit do not completely close, only one of these materials can be charged into the mixer at any one time during calibration. Assuming that fine aggregate bin is to be calibrated first, fill it at least two-thirds full with sand and make sure the coarse aggregate bin is empty. Check to ensure that all bin vibrators are functioning properly and that the Cement Meter-Feeder clutch is disengaged to prevent cement discharge while calibrating the aggregate bins. The operator should set the sand gate control at the approximate setting for the weight desired based on previous experience. Set the throttle as noted above. Discharge and waste enough fine aggregate to ensure that the main conveyor belt is fully primed. Discharge approximately 150 to 200 pounds of fine aggregate into a clean, tared container. Carefully time the run by starting and stopping the stop watch exactly when the main clutch is engaged and disengaged. Record the weight of fine aggregate and the actual time to the nearest 0.1 second. Using these two figures and the time determined above, set up a direct proportion to calculate the amount of fine aggregate delivered in the exact length of time it takes to deliver 94 pounds of cement. If the actual quantity delivered is not within the allowable tolerance of the quantity required, adjust the gate control as needed and repeat the above procedure. Several trial runs may be necessary to obtain the correct gate setting. Once this gate setting has been established, at least three runs should be made to verify that it is correct. Empty the fine aggregate bin, charge the coarse aggregate bin and follow the same procedure as above to determine the coarse aggregate gate setting. If several mixes will be used from the same proportioning unit, coarse and fine aggregate bin curves may be plotted using three or more gate settings. The curves should cover the full range of aggregate flow rates anticipated and should be verified within the appropriate tolerances.

	When admixtures are used the dispensers on the volumetric proportioning unit shall be calibrated. Calibration may be on either a weight or a volume basis. Dilution of admixtures is		When admixtures are used the dispensers on the volumetric proportioning unit shall be calibrated. Calibration may be on either a weight or a volume basis. Dilution of admixtures is
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	====501.1.7.2 Verification (Sec 501.9.4)====		====501.1.7.2 Verification (Sec 501.9.4)====
	Proportioning devices shall be verified by running the one-quarter cubic yard test in accordance		Proportioning devices shall be verified by running the one-quarter cubic yard test in accordance
	with the Job Special provisions. Adjust the mix conveyor so that it is at an angle of about 20 degrees. Set the throttle as noted in [[#501.1.7.1 Calibration (Sec 501.9.3)\|Calibration]]. With all controls set for the designated mix, discharge enough mixed material to ~~insure~~ that the entire length of the mix conveyor contains properly proportioned concrete and then stop the mixing action. Immediately reset the cement meter to zero and swing end of the mix conveyor over the one-quarter cubic yard container (36 in. x 36 in. x 9 in.). Activate the mixer and discharge mixed material into the container until the cement meter count shown that the quantity of cement for one-quarter cubic yard of concrete has been dispensed. Screed the concrete level. Mixes with very low slumps may require vibration. A tolerance of +1/8 inch from the top of the container will be permitted.		with the Job Special provisions. Adjust the mix conveyor so that it is at an angle of about 20 degrees. Set the throttle as noted in [[#501.1.7.1 Calibration (Sec 501.9.3)\|Calibration]]. With all controls set for the designated mix, discharge enough mixed material to ensure that the entire length of the mix conveyor contains properly proportioned concrete and then stop the mixing action. Immediately reset the cement meter to zero and swing end of the mix conveyor over the one-quarter cubic yard container (36 in. x 36 in. x 9 in.). Activate the mixer and discharge mixed material into the container until the cement meter count shown that the quantity of cement for one-quarter cubic yard of concrete has been dispensed. Screed the concrete level. Mixes with very low slumps may require vibration. A tolerance of +1/8 inch from the top of the container will be permitted.

	===501.1.8 Air-Entrained Concrete (Sec 501.10)===		===501.1.8 Air-Entrained Concrete (Sec 501.10)===
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	'''Protex Meter.''' Calibration of pressure-type apparatus is affected by changes in barometric		'''Protex Meter.''' Calibration of pressure-type apparatus is affected by changes in barometric
	pressure such as those caused by changes of temperature and humidity, and by rough handling.		pressure such as those caused by changes of temperature and humidity, and by rough handling.
	Steps (a) through (e) normally need be made only at time of initial calibration, and occasionally there after to check the stability of volume for the calibration cylinder and measuring bowl. Step (f) must be made as frequently as necessary to ~~insure~~ that proper gauge pressure is being used in tests for air content of concrete.		Steps (a) through (e) normally need be made only at time of initial calibration, and occasionally there after to check the stability of volume for the calibration cylinder and measuring bowl. Step (f) must be made as frequently as necessary to ensure that proper gauge pressure is being used in tests for air content of concrete.

	:(a) Calibration of the calibration cylinder. Accurately determine weight of water, w, in grams required to fill the calibration cylinder, using a scale sensitive to 0.5 gram.		:(a) Calibration of the calibration cylinder. Accurately determine weight of water, w, in grams required to fill the calibration cylinder, using a scale sensitive to 0.5 gram.

	:(b) Calibration of measuring bowl. Determine weight of water, W, (in pounds) required to fill the measuring bowl. Use a scale sensitive to 0.1 percent of the weight of the bowl filled with water. Slide a glass plate carefully over the flange of the bowl in a way to ~~insure~~ that the bowl is completely filled with water. A thin film of cup grease smeared on the flange of the bowl will make a water tight joint between the glass plate and top of the bowl.		:(b) Calibration of measuring bowl. Determine weight of water, W, (in pounds) required to fill the measuring bowl. Use a scale sensitive to 0.1 percent of the weight of the bowl filled with water. Slide a glass plate carefully over the flange of the bowl in a way to ensure that the bowl is completely filled with water. A thin film of cup grease smeared on the flange of the bowl will make a water tight joint between the glass plate and top of the bowl.

	:(c) Determination of Constant, R. The constant, R, represents the volume of the calibration cylinder expressed as a percentage of the volume of the measuring bowl. Calculate R by the following equation:		:(c) Determination of Constant, R. The constant, R, represents the volume of the calibration cylinder expressed as a percentage of the volume of the measuring bowl. Calculate R by the following equation:
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	====501.1.9.2 Preparation====		====501.1.9.2 Preparation====
	While working on the 2AA Sheet in the field, care should be taken to ~~insure~~ accuracy and sufficient legibility to permit preparation of the finished sheet by the Division of Construction and Materials for a permanent record. The resident engineer is relieved of the work of drafting the finished 2AA Sheet but is responsible for seeing that the work sheet is properly prepared. Use of an H pencil will often eliminate the need for further work before printing.		While working on the 2AA Sheet in the field, care should be taken to ensure accuracy and sufficient legibility to permit preparation of the finished sheet by the Division of Construction and Materials for a permanent record. The resident engineer is relieved of the work of drafting the finished 2AA Sheet but is responsible for seeing that the work sheet is properly prepared. Use of an H pencil will often eliminate the need for further work before printing.

	The sheet is to be prepared by entering to scale the stationing of the project, including all exceptions and equations, on the proper line near the top of the chart. A scale of 1 in. equals 1000 ft. is recommended for projects over 13,500 ft. in length. For shorter projects or more detailed work a larger scale may be used to advantage.		The sheet is to be prepared by entering to scale the stationing of the project, including all exceptions and equations, on the proper line near the top of the chart. A scale of 1 in. equals 1000 ft. is recommended for projects over 13,500 ft. in length. For shorter projects or more detailed work a larger scale may be used to advantage.