tools to improve pcc smoothness during construction (r06e) · 2015. 3. 1. · real-time smoothness...

Tools to Improve PCC Smoothness During

Construction (R06E)

Date: March 10, 2016

Gary Fick

2

Real-Time Smoothness

What is it?

An integrated system

of profile data

collection sensors and

processing software

that provides real-time

profile feedback to the

contractor.

3

Real-Time SmoothnessSHRP2 Implementation Support

RTS Implementation Support Activities

Objective: Routine use of RTS technology by agencies and

contractors who routinely construct PCC pavement.

4



Task 1: Equipment Loan Program (2015 and 2016)

Full use of an RTS system for two weeks

On-site technical support and training

Budget allows for eleven equipment loans

Projects with a minimum of 10 consecutive mainline paving days

(more is preferable)

Contractor or agency should commit to providing daily QA

profiles during the equipment loan

Contact [email protected] if interested

mailto:[email protected]

5



Task 2: Regional Showcase (Open House)

One day classroom presentations with an on-site RTS

demonstration

In conjunction with an equipment loan project

Travel expenses are covered for up to 10 agency participants

6



Task 3: Workshops

Four hour workshops – contact [email protected]

Tentative agenda

1. Importance of Pavement Smoothness

2. Fundamentals of Pavement Smoothness Measurement

3. RTS Measurement Technology and Practices

4. Fundamentals of Ride Quality and Pavement Profile

Analysis

5. Current Practices for Concrete Pavement IRI Specifications

6. Best Practices for Concrete Paving Operations

7. Using RTS Technology to Improve Concrete Pavement

Smoothness

mailto:[email protected]

7



Task 4: Documentation of Results/Case Studies

Synthesis of contractors’ experience

Case study – Comparing real-time measurements to QA results

Case study – Long-term performance of RTS

Documentation of equipment loans and lessons learned

8



Task 5: Specification Refinement

QC approach

Process improvement

Task 6: Outreach Materials

Quick field reference guide (pocket reference)

Brochures

Project updates (30 minute briefings)

9

Reasons for Using RTS Equipment

• Reduce disincentives

• Increase incentives

• Anticipated change in smoothness acceptance

requirements• PI to IRI

• Change in localized roughness specification limits

10


Benefits of identifying construction artifacts in real-time

Opportunity to correct objectionable profile features caused by:

Stringline disturbance

Padline variability

Non-uniformity of concrete

…

11


Benefits of identifying the impact of process changes in real-

time

Validation of adjustments in 1 hour vs. 12 to 24 hours:

Hydraulic sensitivity relative to machine control input (stringline

and stringless)

Vibrator frequencies

Paving speed

Concrete head

Concrete mixture proportions

…

12

RTS Systems – Which One is Best?

• They both do the same thing - the correct question is,

“which one is best for me?”

• Factors to consider:

Ease of mounting and switching between multiple pavers

Field ruggedness

Familiarity with Ames lightweight

profiler systems

Laser vs. ultrasonic sensors

13

RTS Mounting Locations

• Typically center of each driving lane

• Adjust this for special situations, when tuning the paver:

Tie bar insertion issues

One side of the paver is consistently rougher

Cross-slope changes

14

RTS Mounting Locations

15

RTS Systems:

Daily Setup and Shutdown

• Start-up - approximately 5 minutes

Install sensors and DMI

Connect cables

Input starting station and direction

Start the system

• Shut-down – approximately 5 minutes

Stop the system

Download data to a USB drive

Disconnect cables

Remove sensors and DMI

16

RTS Systems:

Daily Setup and Shutdown

17

Ten Commandments of Concrete

Pavement Smoothness (circa 1988)

Source: ACPA Best Practices for Constructing Smooth Concrete Pavements

Credit: Chapin Cipherd, CMI Corp.

18

21st Century Approach

The “Sweet Spot”

Mixture Factors

Paving Factors

Human Factors

19

Mixture Factors

• Combined gradation

• Between batch uniformity

• Uniform delivery of concrete

20

Combined Gradation

Remember the purpose of an optimized gradation:

• Economically combining aggregate particles to achieve the desired

objectives of:

Reduced paste content

Improved workability

Durability

• An optimized mixture must be workable in the field to achieve

durability

• The Tarantula curve was developed concurrently with a lab test that

evaluates a concrete mixture’s response to vibration

21

Between Batch Uniformity

Consistent combined gradation and water content

• Scales in tolerance

• Uniform stockpile moistures

• Eliminate stockpile segregation

22

Uniform Delivery of Concrete

Translates to minimizing paver stops

• Plant production capacity must be able to feed the paver

23

Paving Factors

• Track line

• Stringline/Stringless model

• Paver setup

Draft/Lead

Sensitivities

Vibrator frequency

Vibrator height

Float pan

• Concrete head

• Curing and texturing

24

Human Factors

• Training

• Experience

• Communication

• Empowerment

25

Using RTS Systems

• Step 1 – Establish a baseline

• Monitor results for 1 to 2 days

• Keep processes static, but make ordinary adjustments

Observe typical responses to the ordinary adjustments

• Mixture

• Vibrators

• Speed

• Head

• Stops

• Etc.

26

Using RTS Systems

• The RTS results are higher than the QC hardened profiles –

what’s up with that?

• Don’t panic

• Just focus on making the RTS results better (lower IRI)

• QC profiles will improve as well

27

Using RTS Systems

• Step 2 – Pick the low hanging fruit

• Eliminate large events that cause excessive localized

roughness

• Stringline/stringless interference

• Paver stops

• Padline issues

• Etc.

28

Localized Roughness Events

• Stringless system interference

29


• Running the paver out of concrete

30


• Stopping the paver

31

Using RTS Systems

• Step 3 – Adjust the paving process to improve overall

smoothness

• Maintain a consistent head

• Lead/draft - setup the paver as flat as possible

• Sensitivities

• Vibrators (height and frequency)

• Mixture

• Paver operation

• Paving speed

32

Overall Smoothness

• Eliminating big events gave us a new “baseline” to adjust

from

• Systematically make changes in small increments

• Get a minimum of 0.1 mile with consistent paving (no big

events) and then evaluate if the adjustment made things

smoother

• Continue adjusting in small increments and evaluating every

0.1 mile

33

Overall Smoothness

• Stay focused and incredible things can happen

• Over a mile per day – average IRI = 28 in/mi

34

Using RTS Systems

• Step 4 – Identify repeating features using a PSD plot and

adjust processes when possible

• Joints

• CRCP bar supports

• Dumping/Spreading loads

35


Questions and Discussion

tools to improve pcc smoothness during construction (r06e) · 2015. 3. 1. · real-time smoothness...

Documents