The Effects of Higher Strength and Associated Concrete Properties ...

Table 1.2.2 Midslab maximum deflection from FWD on I-75, Detroit.
Deflections Inside Lane Middle Lane Outside Lane
(mm) European Michigan European Michigan European Michigan
Average 0.03 0.06 0.03 0.05 0.03 0.05
Maximum 0.04 0.07 0.04 0.06 0.04 0.06
Minimum 0.03 0.05 0.03 0.05 0.03 0.05
Table 1.2.3 Strength and mix requirements for the European and the Michigan
pavements on I-75, Detroit.
European Test Pavement
Property
Top Layer Bottom Layer Lean Base
Michigan
Control
Pavement
28-day Compressive Strength, MPa
(lbf/in 2 )
37.9
(5500)
34.4
(5000)
17.2
(2500)
24.1
(3500)
28-day Flexural Strength, MPa
(lbf/in 2 )
None None None 4.50
(650)
Maximum w/c 0.40 0.42 0.70 0.50
Minimum Cement Content, kg/m 3
(lb/yd 3 )
446
(752)
349
(588)
249
(420)
326
(550)
Maximum Slump , mm
(in)
76
(3)
76
(3)
76
(3)
76
(3)
Air Content (±1.5%) 6.5 6.5 6.5 6.5
Preliminary Conclusions
MDOT is monitoring the test sections for up to 5 years for the FHWA. Conclusions
based on construction experience and first 5 years of service life are:
• Construction of the European pavement design occurred without any major problems.
More familiarity with placing the two-layer concrete mixtures and the exposed
aggregate surface would result in faster construction and may reduce cost.
• The top concrete layer should not be less than 7 cm in thickness to avoid poor
consolidation and thin surface layer.
• The top layer should not have sand particles larger than 1 mm to allow the coarse
aggregate with a nominal diameter of 6-8 mm to lock together better when there is an
exposed surface. The coarser sand wears faster than the basalt coarse aggregate, and
closer packing is expected to reduce tire noise level.
• Both pavement types are performing as expected. There are no transverse cracks in
the short panels of the European pavement, whereas about 28 percent of the Michigan
JRCP 12.5 m panels have either one mid panel crack or two transverse cracks at the
panel’s third points. The cracks are equally scattered across all lanes. This initial
crack pattern is typical of Michigan’s JRCP’s.
This demonstration project has not yet had sufficient traffic and environmental exposure
time to warrant a detailed field and laboratory investigation in this study.
However, since the demonstration project, MDOT has developed new design and
construction requirements to improve long-term pavement performance. MDOT has
modified its concrete pavement mixture to include large size coarse aggregate (62-mm
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