0153.pdf

Prof. Jan OLEK, olek@purdue.edu

Mateusz RADLIŃSKI, matrad@purdue.edu

Maria DEL MAR ARRIBAS, marribas@purdue.edu

School of Civil Engineering, Purdue University, 550 Stadium Mall Dr., West Lafayette, 47907

IN, U.S.A

PREMATURE DETERIORATION OF JOINTS IN SELECTED INDIANA

PORTLAND CEMENT CONCRETE PAVEMENTS

PRZEDWCZESNE ZNISZCZENIE SZCZELIN DYLATACYJNYCH

BETONOWYCH NAWIERZCHNI W STANIE INDIANA

Abstract In the last decade, the progressive deterioration of relatively new portland cement concrete

pavements was observed in several locations in Indiana. This deterioration took a form of cracking and spalling

localized in the upper part of the pavement, typically around the bottom of the saw cut groove. In order to

investigate the cause of this deterioration, 36 of 150-mm diameter cores were extracted from four different

pavements. Although the obtained specimens were subjected to various tests, this paper only contains the results of

air void system analysis, as the ultimate mode of failure appeared to be freeze-thaw related. The results indicate that

even though some of these concretes might have had satisfactory air-void system at the time of placement, its

effectiveness became compromised over time by combined effects of water and salt ingress (formation of ettringite

and Friedel’s salt).

Streszczenie W ciągu ostanich kilkunastu lat w stanie Indiana (USA) zaobserwowano postępujące zniszczenie

stosunkowo nowych nawierzchni betonowych. Przedwczesne zniszczenia w postaci pęknięć i wykruszeń

wystepowaly wokół podluŜnych i poprzecznych szczelin dylatacyjnych (w górnej części nawierzchni, na dnie

nacięcia dylatacyjnego). W celu zbadania przyczyn występujących zniszczeń wykonano 36 odwiertow, z których

pobrano walce o średnicy 150 mm do badań laboratoryjnych. Próbki zostały wycięte z czterech róŜnych odcinkow

drogowych. ChociaŜ pobrane walce poddano kilkunastu testom, w artykule przedstawiono wyniki jednego z

oznaczen. Analiza systemu pustek powietrznych w stwardniałym betonie wskazuje, Ŝe przyczyną przedwczesnego

zniszczenia nawierzchni było częściowe wypełnienie pustek powietrznych etryngitem lub solą Friedela. Obecność

tych związków wskazuje na duŜy stopień akumulacji soli odladzających i zawilgocenia betonu w obrębie nacięć

spowodowany brakiem zdolności dylatacji do odprowadzania wody.

1. Introduction

Some of the 5-10 years-old concrete pavements located in various part of Indiana, USA, that

otherwise perform well, show signs of premature deterioration (in the form of excessive cracking

and spalling) primarily in areas near the longitudinal joints; in several cases, the transverse joints

areas have been affected as well. The deterioration has been observed (among others) at SR 933

near South Bend, on some sections of I-65, as well as on several roads in the Indianapolis area

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(i.e. 86th and Payne Rd). Some of the typical examples of the distress observed are presented in

Figure 1.

Fig. 1. Section of pavement on W 86 th Street, Indianapolis, IN (left) and SR 933 near South Bend, IN (right)

This paper contains the results of air-void system analysis (using ASTM C 457) performed on

number of cores extracted from the following locations:

“on” ramp from US 67 to east-bound I-465 located in the south-west section of

Indianapolis, IN;

W 86 th Street (near Michigan Road) located in the north section of Indianapolis, IN;

· SB I-65 (near MLK Street exit) in Indianapolis, IN

· SR 933 near South Bend, IN (section between Darden Road and Willow Street).

The cores obtained from the W 86th Street were actually removed from two locations along

the eastbound lane. The first location was immediately to the west of the intersection of W 86 th

Street with N. Payne Road and it is referred to in this paper as “before lights” (BL) location.

This section of the pavement was in good condition, with no visible signs of distress. The

second location was immediately to the east of the intersection and it is referred to in this paper

as “after lights” (AL) location. The condition of the pavement at this location was considerably

worse than that to the west of the intersection, with severe to moderate deterioration observed in

both longitudinal and transverse joints (see left side of Figure 1). Due to the significant

differences in the pavement conditions for the BL and AL locations, the test results obtained

from these two sections were analyzed separately.

2. Collection of cores

When selecting the coring locations on the ramp from US 67 to eastbound I-465E and on W

86 th Street an attempt was made to obtain specimens for various cases presented in Figure 2 and

listed below:

A – damaged area of the transverse joint

B – damaged area of the longitudinal joint near the junction of the longitudinal and transverse

joints

C – damaged area of the longitudinal joint away from the transverse joint

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D – mid-span of the slab, undamaged section

E – undamaged transverse joint adjacent to the damaged transverse joint

Fig. 2. Proposed coring locations

3. Preparation of test specimens

3.1 Sampling and testing procedure

A number of specimens needed for various types of tests were prepared by dissecting each of

the collected cores as shown in Figure 3. The specimen for air-void system analysis (shown

hatched), had planar dimensions of 110×110 mm and was generally collected from the top

section of the core. In four instances, the damage to the cores removed from the joints was so

extensive that it was not possible to obtain the specimens directly from the top section of the

core. As a result, these specimens were obtained from the lower portion of the core.

System Analysis

Air-Void

System Analysis

XRD and SEM

Chloride

Concentration

RCP and

Sorptivity

2 X F-T

RCP and

Sorptivity

Fig. 3. Schematic of test specimen locations within each core

3.2 Polishing of specimens for air-void system analysis

All the specimens for air-void system analysis were polished using automatic lapping wheel,

following the procedures of ASTM C 457 [1].

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3.3 Testing procedure

The air-void system analysis was conducted using modified point-count method following

ASTM C 457 [1]. The test was performed in such way that the results were recorded for each

line (traverse) separately, which allowed for determination of the distribution of air voids with

depth of the core (the results for every four lines were averaged to increase the accuracy). In

addition, distinction was made between the entrained and entrapped voids. The selection of

entrapped voids, although arbitrarily, was based on the size (larger than about 1 mm), shape

(irregular rather than round) and location (mostly adjacent to at least one particle of aggregate).

Finally, it should be pointed out that voids in-filled with secondary products were not counted

(regardless of whether they appeared to be entrapped or entrained) as such voids do not

contribute to the freeze-thaw resistance of concrete.

4. Test results

The summary of all test results obtained during the ASTM C 457 analysis is presented in

Table 2. Additionally, the average values and standard deviations for all the relevant air-void

system parameters (total air content, entrained air content, void frequency and spacing factor)

were calculated separately for the group of undamaged and damaged cores at each location.

These results are presented in Figures 4-7.

For reference, provided below are the approximate recommended values of parameters of air-

void system for freeze-thaw resistant air-entrained concrete [2, 3]:

air content: 6.5% (by volume of concrete);

void frequency: > 1.5 times the air content;

specific surface area: 23.6 mm 2 /mm 3 ;

spacing factor: 0.20 mm.

5. Analysis and discussion

As seen in Table 2, for the group of cores obtained from the US 67 ramp, the air content (both

total and entrained) was highest for cores 5F and 9D (5.5 – 6.0%). The air content in all other

cores was about 4% or less, which is significantly lower than 6.5% typically specified for PCC

pavements exposed to freezing and thawing [2,3]. The lowest entrained air content was obtained

for cores 6D and 8A (2.0 - 2.4%). Accordingly, these two cores exhibited the highest values of

spacing factor (0.52 mm and 0.62 mm, respectively), which is considerably above 0.20 mm

considered to be indicative of frost-resistant concrete [2,3]. Both damaged cores (1A and 8A)

had relatively high spacing factor (0.39 mm and 0.62 mm, respectively).

All cores from W 86 th Street BL location had relatively uniform amount of entrained air (in

the range of about 3.0 - 5.0%). However, the values of spacing factor for these specimens were

found to be very low (0.11 mm to 0.16 mm), which is below recommended value of 0.20 mm. It

should be also noted that the values of both void frequency and specific surface (although these

are not independent variables) are very high for all cores from W 86 th Street BL (Table 2). Thus,

the good parameters of air-void system of cores collected from that location appear to explain the

lack of damage observable at the joints.

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Table. 2. Summary of test results from air-void system analysis

All cores obtained from W 86 th Street AL location had relatively low entrained air content

varying from 2.5% (cores 2D and 4D) to 4.7% (core 10E). The cores from this location also

exhibited high scatter in the spacing factor, with values ranging from 0.20 mm (core 3D) to 0.63

mm (core 7A). It can also be noticed that for all damaged cores (7A, 8B, 9F * and 11C) the

measured spacing factor was 0.39 mm or higher.

The entrained air content of all three cores obtained from SR 933 was about 4.0%. The

spacing factor for the cores from mid-span of the slab was 0.41 mm (core 0D) and 0.23 mm

(core 1D). The core obtained from the undamaged transverse joint (2E) had a value of spacing

factor of 0.28.

* Core 9F appeared to be undamaged (no surface damage) but was deteriorated beneath the surface

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