718 - Drilled Shafts - Revision history

Clarkj25: /* Concrete, Grade S2, and Grade T */

2023-04-25T15:40:33Z

Concrete, Grade S2, and Grade T

SchaeferS: Removed 2012 Spec Book tagline link

2022-01-19T15:48:23Z

Removed 2012 Spec Book tagline link

SchaeferS: /* MEASUREMENT AND PAYMENT */

2021-05-12T20:36:58Z

MEASUREMENT AND PAYMENT

McGowanR: /* Tremie Tube Concrete Placement */ Duplicate Text

2019-01-22T16:19:20Z

Tremie Tube Concrete Placement: Duplicate Text

McGowanR: Provided clarification relating to Tremie Tube Concrete Placement along with inspection of shaft after Placing Steel Reinforcement cage

2019-01-22T16:15:29Z

Provided clarification relating to Tremie Tube Concrete Placement along with inspection of shaft after Placing Steel Reinforcement cage

McGowanR: Reverted edits by McGowanR (talk) to last revision by JohnsonN23

2019-01-22T15:57:47Z

Reverted edits by McGowanR (talk) to last revision by JohnsonN23

McGowanR: /* Placing Steel Reinforcement */ Clarification for inspection after placement of reinforcement cage

2019-01-22T15:55:14Z

Placing Steel Reinforcement: Clarification for inspection after placement of reinforcement cage

McGowanR: /* Tremie Tube Concrete Placement */ Clarification for Tremie Tube Concrete Placement

2019-01-22T15:33:47Z

Tremie Tube Concrete Placement: Clarification for Tremie Tube Concrete Placement

JohnsonN23: /* DRILLED SHAFT CONSTRUCTION */ relink

2017-02-14T13:27:28Z

DRILLED SHAFT CONSTRUCTION: relink

McGowanR: /* Concrete, Grade S2, and Grade T */

2015-11-11T01:28:26Z

Concrete, Grade S2, and Grade T

@@ Line 56: / Line 56: @@
 Concrete mix design and spacing of reinforcing bars are critically important construction parameters that help ensure the free passage of concrete through the cage and into the space between the cage and borehole wall.
-The modified slump requirements described in [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction supersede the slump requirements shown in [http://mdotcf.state.mi.us/public/specbook/files/2012/701%20PCC%20for%20Structures.pdf#page=3 Table 701-1A] in Section 701 of the Standard Specifications for Construction.  Construction staff must review and only approve contractor submitted concrete mix designs and concrete quality control (QC) plans, for drilled shaft construction, that meet the modified slump requirements of [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction.  The Special Provision for Quality Control and Acceptance of Portland Cement Concrete, [http://mdotcf.state.mi.us/public/dessssp/spss_source/12SP-604B-05.pdf 12SP-604B-05], does not supersede these requirements.
+The modified slump requirements described in [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction supersede the slump requirements shown in [http://mdotcf.state.mi.us/public/specbook/files/2012/701%20PCC%20for%20Structures.pdf#page=3 Table 701-1A] in Section 701 of the Standard Specifications for Construction.  Construction staff must review and only approve contractor submitted concrete mix designs and concrete quality control (QC) plans, for drilled shaft construction, that meet the modified slump requirements of [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction.
 If concrete for drilled shaft foundations does not meet the modified slump requirements of [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction it should not be allowed.

← Older revision		Revision as of 15:48, 19 January 2022
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	<center><span STYLE="font: 40pt arial;">'''Drilled Shafts'''</span></center>		<center><span STYLE="font: 40pt arial;">'''Drilled Shafts'''</span></center>

−	~~<center>[http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf 2012 STANDARD SPECIFICATIONS FOR CONSTRUCTION - SECTION 718]</center>~~

← Older revision		Revision as of 20:36, 12 May 2021
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	[[Category:Construction Manual]]		[[Category:Construction Manual]]
		+	[[Category: Division 7]]
		+	[[Category: Section 718]]

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 For cased shafts, it is important discharge keep a head of concrete above the bottom of casing to be removed, and then remove the casing slowly, to allow the concrete to fill the annular space created by the case thickness. If the concrete level goes down during case extraction, direct the Contractor to stop the extraction, and add more concrete.
-The concrete must be placed in a timely fashion, so the slump does not go below 4”, as the concrete will not properly envelope the rebar cage, or fill the shaft to the required diameter. The contractor may need to use a retarder in the mix on larger, longer tremie pours to maintain concrete slumps throughout the pour.  See Figure 9 for an example of concrete not filling the required shaft diameter. The contractor may need to use a retarder in the mix on larger, longer tremie pours to maintain concrete slumps throughout the pour.
+The concrete must be placed in a timely fashion, so the slump does not go below 4”, as the concrete will not properly envelope the rebar cage, or fill the shaft to the required diameter. The contractor may need to use a retarder in the mix on larger, longer tremie pours to maintain concrete slumps throughout the pour.  See Figure 9 for an example of concrete not filling the required shaft diameter.
 Allow the concrete to continue flowing at the top of the shaft, until quality concrete displaces all drilling fluid.  Drilling fluid at the top of the shaft may have to be pumped of.

@@ Line 238: / Line 238: @@
 Ensure the Contractor holds down the cage to control vertical displacement during concrete placement or casing extraction.
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 Ensure the Contractor is using a tremie tube of at least 10 inches in diameter.  Inspect the bottom of the Contractor’s tremie tube to ensure there is a bottom plate, valve, or plug so no water can get into the tube and contaminate the concrete prior to placement.
-The tremie tube must be placed at the bottom of the shaft, and once the plate or plug is removed, or valve is opened, ensure the Contractor keeps the discharge end 5 feet to 10 feet immersed in concrete before raising the tremie tube.
+The tremie tube must be placed at the bottom of the shaft, and once the plate or plug is removed, or valve is opened, ensure the Contractor keeps the discharge end 5 feet to 10 feet immersed in concrete before raising the tremie tube. When initially starting the flow of concrete in the tremie pour, the end of the tremie tube must be within one tremie tube diameter of the base
-It is ideal for the concrete to be placed continuously until complete, however, should the Contractor need to withdraw the tremie tube from the concrete, ensure the discharge end is re-sealed, charged with concrete, and inserted back into the concrete at least 10 feet before continuing with the concrete placement.
+It is ideal for the concrete to be placed continuously until complete, however, should the Contractor need to withdraw the tremie tube from the concrete, ensure the discharge end is re-sealed, charged with concrete, and inserted back into the concrete at least 10 feet before continuing with the concrete placement.  The contractor and their concrete supplier should plan ahead and stage and sequence trucks accordingly to ensure a continuous tremie pour.
-For cased shafts, it is important discharge keep a head of concrete above the bottom of casing to be removed, and then remove the casing slowly, to allow the concrete to fill the annular space created by the case thickness.  If the concrete level goes down during case extraction, direct the Contractor to stop the extraction, and add more concrete.
+For cased shafts, it is important discharge keep a head of concrete above the bottom of casing to be removed, and then remove the casing slowly, to allow the concrete to fill the annular space created by the case thickness. If the concrete level goes down during case extraction, direct the Contractor to stop the extraction, and add more concrete.
-The concrete must be placed in a timely fashion, so the slump does not go below 4”, as the concrete will not properly envelope the rebar cage, or fill the shaft to the required diameter.  See Figure 9 for an example of concrete not filling the required shaft diameter.
+The concrete must be placed in a timely fashion, so the slump does not go below 4”, as the concrete will not properly envelope the rebar cage, or fill the shaft to the required diameter. The contractor may need to use a retarder in the mix on larger, longer tremie pours to maintain concrete slumps throughout the pour.  See Figure 9 for an example of concrete not filling the required shaft diameter. The contractor may need to use a retarder in the mix on larger, longer tremie pours to maintain concrete slumps throughout the pour.
 Allow the concrete to continue flowing at the top of the shaft, until quality concrete displaces all drilling fluid.  Drilling fluid at the top of the shaft may have to be pumped of.

← Older revision		Revision as of 15:55, 22 January 2019
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	Ensure the Contractor holds down the cage to control vertical displacement during concrete placement or casing extraction.		Ensure the Contractor holds down the cage to control vertical displacement during concrete placement or casing extraction.

		+	After the reinforcement cage is set, check the depth of the shaft at the center and around the edge of the shaft. If material entered the shaft after the reinforcement cage was set, the reinforcement cage will need to be removed and the entire cross-section of the shaft will need to be re-cleaned in accordance to subsection [https://mdotjboss.state.mi.us/SpecProv/getDocumentById.htm?docGuid=90d58f15-5ac0-42b1-89fc-35076be2c080&fileName=%22718%20Drilled%20Shafts.pdf%22 718.03.F.1.]
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@@ Line 116: / Line 116: @@
 ===[[#DRILLED SHAFT CONSTRUCTION|DRILLED SHAFT CONSTRUCTION]]===
-To track drilled shaft operations, use MDOT [http://mdotcf.state.mi.us/public/webforms/public/1988.pdf form 1988] – DRILLED SHAFT INSPECTION RECORD FOR HIGHWAY SIGNS, LUMINAIRES, AND TRAFFIC SIGNALS.
+To track drilled shaft operations, use MDOT [http://mdotjboss.state.mi.us/webforms/GetDocument.htm?fileName=1988.pdf form 1988] – DRILLED SHAFT INSPECTION RECORD FOR HIGHWAY SIGNS, LUMINAIRES, AND TRAFFIC SIGNALS.
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← Older revision		Revision as of 01:28, 11 November 2015
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	Ensure concrete materials are in accordance with [http://mdotcf.state.mi.us/public/specbook/files/2012/701%20PCC%20for%20Structures.pdf section 701] of the Standard Specifications for Construction, except modifications for the slump requirements per [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction. Concrete Grade S2 is to be used for dry construction, and Concrete Grade T is to be used for wet construction.		Ensure concrete materials are in accordance with [http://mdotcf.state.mi.us/public/specbook/files/2012/701%20PCC%20for%20Structures.pdf section 701] of the Standard Specifications for Construction, except modifications for the slump requirements per [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction. Concrete Grade S2 is to be used for dry construction, and Concrete Grade T is to be used for wet construction.
		+
		+	Concrete mix design and spacing of reinforcing bars are critically important construction parameters that help ensure the free passage of concrete through the cage and into the space between the cage and borehole wall.
		+
		+	The modified slump requirements described in [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction supersede the slump requirements shown in [http://mdotcf.state.mi.us/public/specbook/files/2012/701%20PCC%20for%20Structures.pdf#page=3 Table 701-1A] in Section 701 of the Standard Specifications for Construction. Construction staff must review and only approve contractor submitted concrete mix designs and concrete quality control (QC) plans, for drilled shaft construction, that meet the modified slump requirements of [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction. The Special Provision for Quality Control and Acceptance of Portland Cement Concrete, [http://mdotcf.state.mi.us/public/dessssp/spss_source/12SP-604B-05.pdf 12SP-604B-05], does not supersede these requirements.
		+
		+	If concrete for drilled shaft foundations does not meet the modified slump requirements of [http://mdotcf.state.mi.us/public/specbook/files/2012/718%20Drilled%20Shafts.pdf subsection 718.02] of the Standard Specifications for Construction it should not be allowed.

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