Past Performance (Literature Review)

Composite pavements have been implemented worldwide in the last few decades.  In 

and Spain are known for their wide use of long-life semi-rigid structures in their main road 

networks, which account for 30% to 50% of their highway systems (Thogersen et al., 2004).   

The U.K. highway agencies have used two designs for their flexible composite 

equivalent single-axle loads (ESALs) over 20 years and has a structure comprised of a lean 

concrete base with a maximum thickness of 250 mm (10 in) surfaced with up to 150 mm (6 in) 

of HMA.  The second design is for service a life of more than 20,000,000 ESALs and consists of 

a 200-mm thick HMA on top of a lean concrete base (Parry et al., 1997).  The U.K. had, as of 

1999, 649 km of composite pavements in their main road network, which had been constructed 

between 1959 and 1987 and had carried between 8 and 97 million single-axle (MSA) loads.  A 

composite pavement performance study published by Parry et al. (1999) concluded that there 

was considerable variability in the performance of these composite structures.  In particular, the 

required thickness of the asphalt overlays during maintenance was highly variable.  The new U.K. 

Pavement Design Guide includes a new section that deals with flexible composite pavement 

design and that aims to design pavement structures for traffic levels of 100 MSA or more (U.K., 

2006). 

A study by Merrill et al. (2006) reviewed the experiences of composite pavements in 

Hungary were performing satisfactorily in terms of rutting, cracking, and deflections.  The 

expected life of a semi-rigid pavement structure was found to be statistically longer than that of a 

comparable flexible one.  Semi-rigid structures with relatively thin layers (250 mm [10 in] total 

thickness) performed satisfactorily for a long-life even under heavy traffic.  Moreover, field 

observations confirmed that composite structures tend to have longer lives (i.e., they may be 

classified as long-life pavements). 

There is a very wide use of composite pavements in Spain as documented by Jofre and 

because they do not tend to use a portland cement concrete pavement (PCCP) as the base.  

Instead they use different types of rigid bases that mainly differ from one another in the cement 

content and aggregate type.  The typical rigid base characterization presented by Jofre and 

Fernandez is summarized in Table 1.   

In the United States, composite pavements usually have been the result of PCCP 

creating a composite structure.  This type of rehabilitation action has been used to restore the 

functional performance of an existing pavement and/or to increase the structural capacity in 

order to handle additional and heavier traffic.  The performance of composite pavements may 

vary due to different factors, such as design of the rigid base, selection of an adequate HMA type, 

constructability, and maintainability.  A study of composite pavements presented by Hein et al. 

(2002) concluded that: 

  6

•  The use of an open-graded HMA interlayer does not mitigate reflection cracking  

•  There is an early (3 to 5 years) deterioration due to reflective cracking on the HMA 

from the underlying rigid layer’s discontinuities  

•  The pavement condition ratings based only on the HMA surface do not accurately 

reflect the condition of the overall pavement structure and/or concrete base, e.g., 

faulting and spalling may be effectively hidden from view. 

tải về 1.81 Mb.

Chia sẻ với bạn bè của bạn: