Pavement Design Considerations: Erosion and Fatigue Cracking
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Questions and Answers

What causes the concrete slab to curl according to the text?

  • Latitude
  • Solar radiation (correct)
  • Rainfall
  • Wind velocity
  • How is the temperature differential affected by geographical features?

  • Solar radiation
  • Rainfall
  • Concrete thickness
  • Latitude (correct)
  • What is the function of wind velocity in relation to temperature differential?

  • It stabilizes temperature differential
  • It reduces temperature differential
  • It increases temperature differential (correct)
  • It has no effect on temperature differential
  • How should temperature differential values be estimated for pavement design?

    <p>Using relevant geographical parameters</p> Signup and view all the answers

    What should be done in the absence of local data for temperature differentials?

    <p>Adopt maximum temperature differential values from Table 1</p> Signup and view all the answers

    Which factor is NOT mentioned as influencing the temperature differential in concrete pavements?

    <p>Rainfall intensity</p> Signup and view all the answers

    Which vehicles played a significant role in causing erosion of the foundation?

    <p>Tandem and multi-axle vehicles</p> Signup and view all the answers

    What did the AASHO Road Test indicate about erosion in concrete pavements?

    <p>Erosion of the foundation is an important mode of failure</p> Signup and view all the answers

    What recommendation is made in the guidelines regarding the subbase material?

    <p>Use only non-erodible materials</p> Signup and view all the answers

    Why is it important to collect erosion data along with the condition of GSB and subgrade?

    <p>To inform future guidelines for major rehabilitation</p> Signup and view all the answers

    What is identified as one of the reasons for longitudinal cracking along the wheel path on many highways?

    <p>Presence of water due to cracks and joints</p> Signup and view all the answers

    Why are tandem, tridem, and multi-axle vehicles mentioned specifically in relation to erosion?

    <p>They form a large percentage of total commercial vehicles on highways</p> Signup and view all the answers

    Why should the spacing of contraction joints be limited to 4.5 meters?

    <p>To prevent top-down cracking during night hours</p> Signup and view all the answers

    Which type of joint allows for the expansion of concrete slabs due to temperature rise in summer months?

    <p>Expansion joints</p> Signup and view all the answers

    What is the purpose of contraction joints in concrete pavements?

    <p>To relieve tensile stresses</p> Signup and view all the answers

    What problem can occur if expansion joints in concrete pavements get filled up with dirt and other materials?

    <p>Preventing expansion of concrete slabs</p> Signup and view all the answers

    How are longitudinal joints different from transverse joints in concrete pavements?

    <p>Longitudinal joints run parallel to traffic flow, while transverse joints run perpendicular.</p> Signup and view all the answers

    What is considered for the design of pavement thickness in in-service cement concrete pavements?

    <p>Flexural stress due to traffic loads and temperature differentials</p> Signup and view all the answers

    Which factor is not normally considered critical to the thickness design of cement concrete pavements?

    <p>Moisture change</p> Signup and view all the answers

    Which condition illustrated in Figure 3 and 4 is likely to produce Bottom-Up Cracking (BUC)?

    <p>Axle load placed in the middle of the slab during mid-day</p> Signup and view all the answers

    When is the flexural stress at the bottom layer of the concrete slab maximum?

    <p>During the day hours</p> Signup and view all the answers

    Where do the locations of points of maximum flexural stress occur at the bottom of the pavement slab?

    <p>At the same locations with or without tied concrete shoulders</p> Signup and view all the answers

    What do the tyre imprints from single, tandem, and tridem axles indicate?

    <p>They are tangential to the longitudinal edge</p> Signup and view all the answers

    What is the stress due to a single axle load of 200 kN with a temperature change of 17ºC and a tied concrete shoulder?

    <p>Fig.IV.45</p> Signup and view all the answers

    Which figure shows the stress due to a tandem axle load of 320 kN with no temperature change and no concrete shoulder?

    <p>Fig.IV.55</p> Signup and view all the answers

    For a single axle load of 120 kN and a temperature change of 21ºC with a tied concrete shoulder, which figure provides the stress information?

    <p>Fig.IV.48</p> Signup and view all the answers

    In which figure is the stress due to a single axle load of 240 kN, a temperature change of 17ºC, and a tied concrete shoulder presented?

    <p>Fig.IV.46</p> Signup and view all the answers

    For a tandem axle load of 400 kN and no temperature change or concrete shoulder, refer to which figure for the stress data?

    <p>Fig.IV.56</p> Signup and view all the answers

    Which figure illustrates the stress due to a single axle load of 160 kN, a temperature change of 21ºC, and a tied concrete shoulder?

    <p>Fig.IV.49</p> Signup and view all the answers

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