two-lift paving - project background, tasks, and findings

79
Two-Lift Concrete Paving Workshop 5/23/2013 Texas State University & University of Texas at Austin

Upload: center-for-transportation-research-ut-austin

Post on 20-Jan-2015

164 views

Category:

Education


1 download

DESCRIPTION

A Two-Lift concrete Paving (2LCP) workshop was organized as a part of the Texas Department of Transportation (TxDOT) project 0-6749: Feasibility Study of Two-Lift Concrete Paving (2LCP). This workshop was conducted at the J. J. Pickle Research Campus (PRC), The University of Texas at Austin, Austin, TX on May 23rd, 2013. Dr. Jiong Hu, Texas State University, Research Supervisor, and Dr. David Fowler, The University of Texas at Austin, Co-Research Supervisor, co-chaired the workshop. The workshop offered the option of attending in person or remotely through webinar. Fifty-one attendees were present remotely or in person; 28 in person and 23 persons remotely.

TRANSCRIPT

Page 1: Two-Lift Paving - Project Background, Tasks, and Findings

Two-Lift Concrete Paving Workshop

5/23/2013Texas State University & University of Texas at Austin

Page 2: Two-Lift Paving - Project Background, Tasks, and Findings

Welcome and opening comments

Mr. Darrin JensenDr. Jiong Hu

2

Page 3: Two-Lift Paving - Project Background, Tasks, and Findings

Self introduction of attendees

3

Page 4: Two-Lift Paving - Project Background, Tasks, and Findings

Background of project:Why two-lift paving?

Dr. David Fowler

4

Page 5: Two-Lift Paving - Project Background, Tasks, and Findings

What is two-lift paving?Placing two layers of concrete, wet on wet, rather than

the usual single lift of concrete.Bottom layer is much thicker, e.g. 8 or 9 in, and the top

layer is much thinner, e.g. 2 or 3 in.Bottom layer can contain aggregates that are not suitable

for top layer.Top layer contains better quality aggregates

5

Page 6: Two-Lift Paving - Project Background, Tasks, and Findings

Major benefits1. Permits concrete with lower unit cost to be used

for lower layer significant amounts of local materials including aggregates

that are inappropriate for surface courses including recycled and high CTE coarse aggregates and carbonate fine aggregates which reduces transportation

Lower cement contentsHigher amounts of supplementary cementitious materials

6

Page 7: Two-Lift Paving - Project Background, Tasks, and Findings

2. More efficient and economical use of specialized mixtures to produce desirable surface characteristics for top layer

Improved skid resistanceReduced noise Improved durability

7

Page 8: Two-Lift Paving - Project Background, Tasks, and Findings

Importance to TxDOT Some areas including Dallas and Fort Worth are faced

with depleting sources of quality natural silica sands.The carbonate manufactured sands make good concrete

but are not suitable for concrete pavement surfaces due to polishing. Fine aggregates have the greatest influence on skid resistance in

concrete pavements. Softer carbonate fines tend to polish faster than harder silica

aggregates

8

Page 9: Two-Lift Paving - Project Background, Tasks, and Findings

Skid Resistance – Aggregate Test

The test adapted by most highway state agencies is the acid insoluble residue test (AI).

It was originally 28% in Texas and effectively omitted all carbonate fine aggregates.

When the specifications were rewritten in 1993, the limit was set at 60% because that was representative of the value used by the districts.

99

Page 10: Two-Lift Paving - Project Background, Tasks, and Findings

Skid Resistance – AI TestThe minimum acid insoluble residue limit in Texas was

originally 28%.This limit effectively omitted all carbonate fine

aggregates.Between 1982 and 1993, some districts had started

using higher requirements by plan note.When the specifications were rewritten in 1993, the

limit was set at 60% because that was representative of the value used by the districts.

1010

Page 11: Two-Lift Paving - Project Background, Tasks, and Findings

Skid Resistance – Fine Aggregates

11

Hard siliceous FA

Original Section

Abraded SectionSoft limestone FA

Texture created by finishing technique

11

Page 12: Two-Lift Paving - Project Background, Tasks, and Findings

High Microfine (aggregates passing #200) MFA Implementation Project

Sect 1 – 5%

Sect 2 – 10%

Sect 4 – Optimized

Sect 3 – 15%

1212

Page 13: Two-Lift Paving - Project Background, Tasks, and Findings

Section 1 – 5% Microfine Addition (Right lane)

On Wheel Paths Between Wheel Paths

1313

Page 14: Two-Lift Paving - Project Background, Tasks, and Findings

Skid Resistance - Concrete

14

Locked-Wheel Skid Trailer

Dynamic Friction Tester (DFT)14

Page 15: Two-Lift Paving - Project Background, Tasks, and Findings

DFT60 vs. SN(50)smooth Measured (concrete: carpet drag + tined)

1515

Page 16: Two-Lift Paving - Project Background, Tasks, and Findings

Field Sections – Blended vs. 100% MFA

1616

Page 17: Two-Lift Paving - Project Background, Tasks, and Findings

Friction Results at 160,000 Cycles for Blended Sands

1717

Page 18: Two-Lift Paving - Project Background, Tasks, and Findings

What is the implication for two-lift paving?100% carbonate fine aggregates can’t be used.Blending may permit up to 60% carbonate fines in top lift

and 100% in bottom lift.

18

Page 19: Two-Lift Paving - Project Background, Tasks, and Findings

Reduction in amount of natural sand

For single lift 100% natural sands = 100% N.S. For two lift, 10” bottom lift and 2” top lift using 100% natural sand = 2/12 x 100 = 16.7% N.S. For two lift with 40% N.S. and 60% MFA for 2” top lift = 0.4 x 16.7 = 6.7% N.S.

19

Page 20: Two-Lift Paving - Project Background, Tasks, and Findings

What we hope to learnUnder what conditions is two-lift paving appropriate for

Texas?This involves many factors: Economics Materials Equipment Construction Specifications

20

Page 21: Two-Lift Paving - Project Background, Tasks, and Findings

Project Tasks

Dr. Jiong Hu

21

Page 22: Two-Lift Paving - Project Background, Tasks, and Findings

Project Tasks

Project 0-6749: Feasibility Study of Two-lift Concrete PavingTask 1 Literature survey of past experience of 2LCPTask 2 Evaluation of the state-of-the-practice of 2LCPTask 3 Summary of construction perspectives of

implementation of 2LCPTask 4 Cost effectiveness analysis and best practice of

2LCP

22

Page 23: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1 Literature survey of past experience of 2LCP

23

Task 1.1 Summary of previous experiences and past performance of 2LCP

Task 1.2 Summary of potential benefits, challenges and cost effectiveness of 2LCP

Page 24: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1.1 Summary of previous experiences and past performance of 2LCP

24

YearCountry

/State Highway/Location EAC?Length (mi.)

Traffic (ADT) References

Euro

pean

Exp

erie

nce

1989 Austria Freeway A1 Y NA (Tompkins 2009) (SHRP2)1994 Austria A1 near Eugendorf Y NA 56,000 (Tompkins 2009) (SHRP2)1994 Austria A1 near Traun Y NA 55,000 (Tompkins 2009) (SHRP2)1999 Austria A1 near Vorchdorf Y NA 56,000 (Tompkins 2009) (SHRP2)2003 Belgium N511 at Estaimpuis* Y 0.8 2,000 (Debroux 2005)2005 Belgium E34 motorway in Zwijndrecht * 1.9 (Rens 2008)2008 Germany A6 Near Amberg Y 13 80,000 (Tompkins 2009) (SHRP2)NA France Highway A71 NA (Cable 2004)NA Germany Munich Airport NA (Cable 2004)

US

Expe

rien

ce

1976 Iowa US 75 NA (Bilec 2010)1976 North Dakota US 2 b/w Rugby and Leeds NA (Bilec 2010)1977 Florida US 41 2.5 (Bilec 2010) (Cable 2004)1994 Michigan I-75, NB Y 1 (Smiley 2010) (Bilec 2010)

1997 Kansas NA Y

0.7

(Cable 2004) (Wojakowski 1998)0.40.8

2008 Kansas I-70 in Saline County Y 5 (Fick 2009) (CP Road Map 2010)2008 Pennsylvania Mon-Fayette Expressway NA (Bilec 2010)

2010 MinnesotaI-94, Cell 71 Y NA 27,500

(Akkari 2011) (Tompkins 2011) I-94, Cell 72 Y NA 27,5002012 Illinois Tollway 4.2 (Gillen 2012)

Avg 3.03 43,429

*CRCP section

Page 25: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1.1 Summary of previous experiences and past performance of 2LCP

25

YearCountry

/State Highway/Location

Bottom LiftThicknes

s (in.) AggregateSlump (in.) Air (%)

Strength (psi)

Euro

pean

Exp

erie

nce

1989 Austria Freeway A1 8.5 RCA and RAP1994 Austria A1 near Eugendorf 8.3 RCA, MSA 1.26"1994 Austria A1 near Traun 7.9 RCA, MSA 1.26"1999 Austria A1 near Vorchdorf 8.3 RCA, MSA 1.26"2003 Belgium N511 at Estaimpuis* 6 Porphyry 0.59 52005 Belgium E34 motorway in Zwijndrecht * 7 Broken stone, max 60% RCA2008 Germany A6 Near Amberg 10 River gravelNA France Highway A71 NA Local limestoneNA Germany Munich Airport 9.5 Local gravel

US

Expe

rien

ce

1976 Iowa US 75 9 60% RCA, 40% RAP1976 North Dakota US 2 b/w Rugby and Leeds 6 NA1977 Florida US 41 9 Limestone1994 Michigan I-75, NB 7.5 Dolomitic limestone 5000

1997 Kansas NA

7 15% RAP7 High abs. limestone7 Limestone & pea gravel

2008 Kansas I-70 in Saline County 11.8 Limestone 1.3 72008 Pennsylvania Mon-Fayette Expressway 8 NA

2010 MinnesotaI-94, Cell 71 6 50% RCA, 1I-94, Cell 72 6 Relaxed agg. Grad. 1

2012 Illinois Tollway 8 RAP& CM-11 Limestone 3 6.5 3500Avg 7.9 1.4 6.2 4250

Page 26: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1.1 Summary of previous experiences and past performance of 2LCP

26

YearCountry

/State Highway/Location

Top LiftThickness (in.) Aggregate

Slump (in.)

Air (%)

Strength (psi)

Euro

pean

Exp

erie

nce

1989 Austria Freeway A1 1.6 Harder aggregate1994 Austria A1 near Eugendorf 1.6 Diabase aggregate, MSA 0.31"1994 Austria A1 near Traun 2 Diabase aggregate, MSA 0.43"1999 Austria A1 near Vorchdorf 2 Diabase aggregate, MSA 0.43"2003 Belgium N511 at Estaimpuis* 2 Porphyry 1.2 42005 Belgium E34 motorway in Zwijndrecht * 2 Broken stone, with polishing resistance requirement

2008 Germany A6 Near Amberg 2 Crushed granite, gap-graded, MSA 0.31"

NA France Highway A71 2 Harder aggregatesNA Germany Munich Airport 5.5 Crushed granite

US

Expe

rien

ce

1976 Iowa US 75 4 All virgin materials

1976 North Dakota US 2 b/w Rugby and Leeds 3 Crushed rock and sand1977 Florida US 41 3 Limestone1994 Michigan I-75, NB 2.5 Ontario trap rock (crushed basalt) 5500

1997 Kansas NA

3 Limestone3 Rhyolite3 Limestone & pea gravel

2008 Kansas I-70 in Saline County 1.6 Rhyolite 1.9 7.52008 Pennsylvania Mon-Fayette Expressway 4 NA

2010 MinnesotaI-94, Cell 71 3 ½” and 3/8” W. Chips Granite 1 5600I-94, Cell 72 3 ½” W. Chips and 3/8” W. Chips 1 5600

2012 Illinois Tollway 3.5 CM-11 Limestone 3 6.5 3500Avg 2.7 1.62 6 5050

Page 27: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1.2 Summary of potential benefits, challenges and cost effectiveness of 2LCP

27

Additional requirements for 2LCP Time lag between lifts (up to 30 mins/ 30-60 mins) Additional mixing plants (drums), paving machines, belt

placer and extra trucks. Additional crew members and better trained workforceWell organized jobsite and scheduling of operating additional

equipment Bottom lift concrete was placed with spreader, spreader box,

Rex Belt placer, or two belt spreader. Top lift was placed with slip-form paver in every project.

Page 28: Two-Lift Paving - Project Background, Tasks, and Findings

Task 1.2 Summary of potential benefits, challenges and cost effectiveness of 2LCP Benefits of using 2LCP - Use low quality materials in bottom

layer and high quality materials in top layer. Locally available low quality/high polish materials can be used

in bottom lift. Recycled material can be used. Top lift is relatively thinner and less high quality aggregate

needed; makes it an economical choice. Challenges of using 2LCP Required additional equipment and construction requirements,

including a second paver, second batch plant etc. Construction scheduling and planning is also considered as a major

challenge to adoption of the 2LCP concept in the United States. While experiences in Europe shows comparable cost (of 2LCP

comparing to traditional one lift paving), for these experimental projects the cost of 2LCP was twice than the conventional concrete pavement.

28

Page 29: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2: Evaluation of the State-of-the-Practice of 2LCP

Task 2.1 Surveys and interviews of contractors and agencies with experience in use of 2LCP.

Task 2.2 Surveys and interviews of contractors and TxDOT personnel regarding concerns with 2LCP

Task 2.3 2LCP workshop

29

Page 30: Two-Lift Paving - Project Background, Tasks, and Findings

Task 3 Summary of construction perspectives of implementation of 2LCP

30

Properties of each lift Material requirements, thickness of two lifts, slump, air

content, set time and permeability

Minimum requirements of material Aggregate gradation, recycled aggregate limits, admixture

requirements, compressive strength, modulus of rupture and durability

Surface characteristics Type of aggregate, skid resistance, friction, noise and splash

Page 31: Two-Lift Paving - Project Background, Tasks, and Findings

Task 3 Summary of construction perspectives of implementation of 2LCP

31

Additional equipment, construction, and scheduling requirements a second paving machine a second batch plant (or second mixer and additional

aggregate bins) a second belt placer/spreader (in place of a second paving

machine) extra hauling and extra labor for hauling and running the

second batch plant (mixer) and placer/spreader

Page 32: Two-Lift Paving - Project Background, Tasks, and Findings

Task 3 Summary of construction perspectives of implementation of 2LCP

32

Concerns of Implementation of 2LCP Extra permits and land space for two paving plantsWell organized jobsite and scheduling of operating additional

mixing plant, paving machines and trucks Clear definition of “stiff” of bottom lift Pavement vibration system to minimize potential for

segregationMinimum thickness of the top lift Maximum/optimum time lag to eliminate potential

debonding (In K-96 project minimum waiting time of 30 minutes was necessary to prevent mixing of the two lifts. In the same project, low w/c concrete was used in top lift without any debonding problem)

Durability (In Florida 23 sections out of 33 sections are still in service. The other ten sections were removed within 2 years of service. )

Page 33: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4 Cost effectiveness analysis and best practice of 2LCP

Task 4.1 Cost effectiveness of 2LCPTask 4.2 Feasibility study of the most promising

practice of 2LCP

33

Page 34: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.1 Cost effectiveness of 2LCP

34

Changes (increases) of labor and equipment costs between two-lift pavements and traditional single lift pavements need to be quantified to effectively determine if material and/or life-cycle costs can offset the additional costs on a project specific basis.

Research team will work with PM & PMC to develop case studies of potential cost benefit (both construction cost and life cycle cost) in selected districts facing aggregate shortages to justify cost effectiveness.

Also included, will be an analysis of potential economic benefits of surface improvements.

Page 35: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.1 Cost effectiveness of 2LCP

35

Type of Pavement Thickness Cost of Materials

(CY)

Pavement Cost-in-

Place (CY)

Cost of Pavement

(SY)

Standard Mix 12” $57 $99 $33

Durable Mix 12” $102 $144 $48

Two-Lift

Bottom-Lift 10” $57 $108 $30

Surface Lift 2” $102 $190 $11

Identifies $/SY of 2LCP to be $8 more than a standard mix and $7 lower than a durable mix. (Hoard 2009)

Case Study - Kansas I-70 2008

Page 36: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.1 Cost effectiveness of 2LCP

Rao S., Darter M.I., Composite Pavement Systems – A Sustainable Approach for Long-Lasting Concrete Pavements, 10th International Conference on Concrete Pavements, 2012.

Case Study - MnRoad SHRP2 2010

36

Page 37: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.1 Cost effectiveness of 2LCP

Krummen S., Constructing a Composite Pavement from Subgrade Up, 91st Annual TRB Meeting, January 22, 2012.

Case Study - MnRoad SHRP2 2010

Conventional Concrete Composite Concrete

Mix Production $5,501,000 $4,850,000

Pavement Placement $809,000 $1,325,000

Total Pavement Cost $6,310,000 $6,175,000

Unit Cost $20.38/sy $19.94/sy

$135,000 Net Cost Advantage$0.44/cy less

(2% Discount)

37

Page 38: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.1 Cost effectiveness of 2LCP

38

One-Lift Paving (Local Agg.)

One-Lift Paving (Imported Agg.)

Two-LiftPaving

Material Costs

Top Lift -

Bottom Lift NA NA

Construction Costs

Mixing Plants - -

Pavers - -

Extra Equipment

- -

Extra Labor - -

Current Costs ?() ? () ? ()

Maintenance Costs ?()

LCC ? ? ?

Page 39: Two-Lift Paving - Project Background, Tasks, and Findings

Task 4.2 Feasibility study of the most promising practice of 2LCP Research team will provide TxDOT with a recommended best practice

protocol for implementing and managing a cost effected 2LCP project.

39

Page 40: Two-Lift Paving - Project Background, Tasks, and Findings

Findings from Tasks 2

Mr. Michael Grams (Texas State University)Mr. Md Sarwar Siddiqui (CTR, University of Texas)

40

Page 41: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Surveys and interviews of contractors and agencies experience with 2LCP

Mr. Michael Grams (Texas State University)

41

Page 42: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2: Evaluation of the State-of-the-Practice of 2LCP

Task 2.1 Surveys and interviews of contractors and agencies with experience in use of 2LCP.

Task 2.2 Surveys and interviews of contractors and TxDOT personnel regarding concerns with 2LCP

Task 2.3 2LCP workshop

42

Page 43: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Surveys and interviews of contractors and agencies experience with 2LCPA detailed sixteen question survey was issued

through Survey Monkey to both domestic and European contractors, suppliers, researchers, and Department of Transportation personnel who were identified through a literature review as having experience with 2LCP.

The survey was divided into 5 categories that covered: general information of the respondent, mix design and material properties, construction, cost, and overall experience of 2LCP.

Over 100 invitations were sent out. A total of 26 individuals responded and took the survey, including 9 through phone interviews.

43

Page 44: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Personnel Participated Surveys

44

Name Affrications ProjectPeter Schöller Österreichische Betondecken Arge EuropeRonald Blab Vienna University of Technology Austria, Germany and Slowenia

Luc Rens FEBELCEM - EUPAVE BelgiumThomas Sorel MnDOT MnROAD

Thomas Kazmierowski Ontario Ministry of Transportation Highway 407, TorontoJosé Tadeu BALBO USP NA

Arjan Venmans provincie Noord-Brabant The Netherlands Veghel, The Netherlands, secondary road N279

Jussara TanesiFHWA-TFHRC-HRDI Aggregate/Petrographic Lab

(APL) Kansas I-70Ben Worel Minnesota Department of Transportation MnROAD (Interstate - 94)

James Crites Parsons Corp (on behalf of DFW Airport) NARichard Abell Highways Agency Kessignland, Suffolk

Mark B Snyder ACPA - PA Chapter Pennsylvania Turnpike - Mon-Fayette ExpwyMark Watson Minnesota Department of Transportation MnROAD I-94

Suneel N. Vanikar FHWA Several demonstration projects in USADenis Thebeau Ministere des transports du Quebec Hwy 15 Mirabel Northboun Quebec CanadaJohn Donegan Aggregate Industries UK A449 - South Wales, UK

Alfred Weninger-Vycudil PMS-Consult GmbH, Naglergasse 7, Vienna, Austria Austria and GermanySteven Gillen Illinois Tollway I-88 Illinois Tollway

Robert Rasmussen Transtec I-70, EuropeJim Grove FHWA Kansas I-70

Tom Cackler CP Tech Kansas I-70James Cable Cable Construction NAGary Fick Trinity Construction Kansas I-70

Tim Gerhardt Koss Construction Kansas I-70Ron Meskis Gunter & Zimmerman NA

Page 45: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Surveys and interviews of contractors and agencies experience with 2LCP

45

Page 46: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey – General Information

46

Question2: How many years do you have with paving experience?

Question3: Which of the following best describe your field of experience in paving?

Results from 25 valid responses Results from 25 valid responses

4%

0%

8%

88%

0 to 5

6 to 10

11 to 15

Over16

24%

32%

40%

4%

Design

Construction

Research

Equipment

Page 47: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey A – General Information/Cost

47

Question5: Major reason for using 2LCP vs. traditional paving??

Results from 22 valid responses

Question11: Which of the following attributed to the greatest impact to overall 2LCP project cost?

Results from 19 valid responses

6%

28%

13%

44%

9%

Agg. AvailabilitySurface Char.EconomicExperimentationOthers

0%

66%3%

8%

13%

10%

Extra SupervisionExtra EquipmentExtra ManpowerUnexpected ExpendituresPreplanningOthers

Page 48: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 – General Information/Mix Design & Materials Properties

48

Lane Mile ADT Top Lift Thickness Bottom Lift Thickness

Count 8 7 11 10

Max 7450 140000 6.0 8.3

Min 0.19 4000 1.6 6.0

Avg 954 47214 3.0 6.9

Stdev 2625 45170 1.2 1.0

Aggregate Type

Top – Coarse Aggregate Basalt rocks and diabase rocks, Porphyry, Dolomitic sandstone, Granite, Flint gravel, whinstone, limestone

Top – Fine Aggregate River sand, manufacture sand, natural sand

Bottom – Coarse Aggregate

Old pavement, RCA, Porphyry - Limestone - Recycled concrete , Flint Gravel

Bottom – Fine Aggregate River sand, natural sand

Page 49: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey A – Construction

49

Question 9: Please rate the following aspects of 2LCP vs. traditional paving methods

Question10: Please identify the way(s) that challenges of 2LCP were overcome most.

Results from 22 valid responsesResults from 24 valid responses

13%

0%

73%

14%

Extra SupervisionUnexpected ExpendituresPreplanningOthers

0%10%20%30%40%50%60%70%80%90%100%

Sche

dulin

g

Additio

nal equ

ipmen

t

Aggregate selection

Mixing

Placing

Consolidation

Curin

g

QA/

AC

5=substaintial

4

3=extra effort required

2

1=the same

Page 50: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey A – Overall Experience

50

Question12: On a scale of 1-5 (1=worse and 5=best), please rate your overall experience with 2LCP

Question13: Would you like to participate on another 2LCP project?

Results from 22 valid responsesResults from 22 valid responses

0% 0%

41%

45%

14%

1=worse

2

3

4

5=best

91%

9%

Yes

No

Page 51: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey A – Overall Experience

51

Question14: On a scale of 1-5 (1=immediate need and 5 = no need at all), please rate your opinion on need for a 2LCP at this time

Question15: If you chose there is not a need for 2LCP at this time, when do you think there will be a need?

Results from 11 valid responsesResults from 22 valid responses

9%

14%

36%

23%

18%

1=immediate need2345=no need at all

37%

27%

18%

9%

9%

In 1 to 2 yearsIn 3 to 5 yearsIn 6 to 10 yearsIn 11 to 20 yearsMore than 30 years

Page 52: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.1 Survey A - Comments regarding needs for 2LCP

52

Comments

Pros

With the 2LCP it is possible to create a higher-quality concrete surfaces and the opportunity to recycle old concrete pavements. With the two layer you can use different consistencies between the upper and lower concrete. In Austria, we are convinced of this 2LCP method since decades.

Higher priority needs at this time, but technology has technique has interest due to potential for sustainability benefits.

Better utilization of local aggregates or recycled aggregates; friction; reduced noise. Decrease in supply of high quality aggregate and higher transportation (trucking) costs

Desirable to ensure most economic use of aggregate Contractor unable to achieve required ride quality with single layer

Depends on location and aggregate availability - its something new that must also be accepted as an option Choice is ultimately left to the owner Main reason is reduced noise level of fine exposed aggregate concrete. However, comparable noise levels

have recently been met with a single layer concept of exposed aggregate concrete. So, the question is if it is worth facing the extra efforts and risks.C

ons

XXX is fortunate to have very good quality aggregate available across most of the state. We have not felt the need for 2LCP.

Original reason is traffic noise nowadays we would make a concrete road with a silent asphalt topping Experience was mainly for skid resistance issue but up to now, we are disappointed even if we used hard

aggregates. Need 2 sets of paving machine or special piece of kit. Since resistance asked of 35 MPa is pretty low, powerful brushing equipment for exposed aggregate cannot be used within 24 hrs so we have problems of uniformity of texture.

Method is new and therefore higher bids are received and should be accepted as an option

Page 53: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.2 Surveys and interviews of contractors and TxDOT personnel regarding

concerns on 2LCP

Mr. Md Sarwar Siddiqui (CTR, University of Texas)

53

Page 54: Two-Lift Paving - Project Background, Tasks, and Findings

Task 2.2 Surveys and interviews of contractors and TxDOT personnel regarding concerns on 2LCPContact contractors and TxDOT personnel from the

larger urban districts and the Construction Division’s Pavements and Materials and Tests for their initial inputs regarding concerns with 2LCP.

Prepare survey for this focused group and summarize those survey and obtain specific information.

54

Page 55: Two-Lift Paving - Project Background, Tasks, and Findings

Survey for Potential Two-Lift Paving (2LCP) UsersTarget audience is TxDOT personnel and pavement

contractors.Online survey was the primary method of response.Total of 12 responses were received.

55

Page 56: Two-Lift Paving - Project Background, Tasks, and Findings

Survey Responders Distribution

42%

50%

8%

ContractorsTxDOTOthers

56

Page 57: Two-Lift Paving - Project Background, Tasks, and Findings

Paving Experience (Years)

8%

38%

0%

54%

0-56-1011-15Over 16

57

Page 58: Two-Lift Paving - Project Background, Tasks, and Findings

Field of Experience in Paving

23%

54%

23%

0%

Design

Construction

Research

Equipment Manufacturer/Designer

58

Page 59: Two-Lift Paving - Project Background, Tasks, and Findings

Experience with Two Lift Concrete Paving

39%

31%

15%

15%have heard

not familiar

participate in a project

like the opportunity toparticipate

59

Page 60: Two-Lift Paving - Project Background, Tasks, and Findings

Major Issues to Implement 2LCP

90.9%81.8%

0.0%

18.2%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Constructability Increased cost Maintenance Materialcompatibility

60

Page 61: Two-Lift Paving - Project Background, Tasks, and Findings

Major Concern with 2LCP

53.8%

69.2%

0.0%

23.1%15.4%

0%10%20%30%40%50%60%70%80%

Constructability Increased cost Maintenance Materialcompatibility

I do not haveany major

concerns with2LCP

Responders also selected additional labor and equipment and coordination of two plant batching as other potential concerns. 61

Page 62: Two-Lift Paving - Project Background, Tasks, and Findings

Degree of Concern of Various Aspects

8%25% 17%

0%

33%17%

0% 0%

42%

42%

8%

8%

17%25%

17% 17%

42%33%

25%

25%

17% 25%

25%42%

8%

0%

17% 42%

25%8%

25%8%

0% 0%

33% 25%8%

17% 33% 33%

Very Strong Strong Moderate Low None

62

Page 63: Two-Lift Paving - Project Background, Tasks, and Findings

Likelihood of Implementing 2LCP

7%

46%31%

8%8%

NoLowModerateStrongVery Strong

63

Page 64: Two-Lift Paving - Project Background, Tasks, and Findings

Need of 2LCP

8%8%

8%

38%

38% NoLowModerateStrongVery Strong

64

Page 65: Two-Lift Paving - Project Background, Tasks, and Findings

SummaryMore than 50% of the respondents have over 16 years

of experience.Approximately half of the respondents are experienced

in construction followed by design and research. No equipment manufacturers participated in the survey.

About 30% of the participants had never heard of 2LCP. About 40% had heard and 15% had participated in 2LCP projects.

65

Page 66: Two-Lift Paving - Project Background, Tasks, and Findings

SummaryConstructability and increased cost are the two major

concerns in implementing 2LCP.Most of the survey takers have low to moderate

likelihood of implementing 2LCP.76% of the participants indicated strong to very strong

need for 2LCP.

66

Page 67: Two-Lift Paving - Project Background, Tasks, and Findings

Invited Presentations

67

Page 68: Two-Lift Paving - Project Background, Tasks, and Findings

TxDOT Prospective

Mr. Andy Naranjo, TxDOT

68

Page 69: Two-Lift Paving - Project Background, Tasks, and Findings

Introduction of two-lift paving

Dr. Peter Taylor, CP Tech Center

69

Page 70: Two-Lift Paving - Project Background, Tasks, and Findings

Designers’ viewpoints

Mr. Luc Rens, EuPave

70

Page 71: Two-Lift Paving - Project Background, Tasks, and Findings

Environmental performance

Mr. Joep Meijer, The Right Environment

71

Page 72: Two-Lift Paving - Project Background, Tasks, and Findings

Agency viewpoints

Mr. Shreenath Rao ARA, IL Tollway

72

Page 73: Two-Lift Paving - Project Background, Tasks, and Findings

Contractors’ viewpoints

Mr. Tim Gerhardt, Koss Construction

73

Page 74: Two-Lift Paving - Project Background, Tasks, and Findings

Pavement equipment suppliers

Mr. Kevin Klein, Gomaco

74

Page 75: Two-Lift Paving - Project Background, Tasks, and Findings

Two-lift paving research

Mr. Alex Brand, University of Illinois

75

Page 76: Two-Lift Paving - Project Background, Tasks, and Findings

Organized Discussions

76

Page 77: Two-Lift Paving - Project Background, Tasks, and Findings

Summary of Major Issues and Findings

Dr. David Fowler

77

Page 78: Two-Lift Paving - Project Background, Tasks, and Findings

Action Items

Dr. Jiong Hu

78

Page 79: Two-Lift Paving - Project Background, Tasks, and Findings

Adjourn

79