Aashto method, Civil Engineering

Question 1: A stationary 40 kN single axle load (applied on a circular contact area of radius = 152 mm = 6") is applied to each of the flexible pavement structures indicated below. Assuming linear elastic behaviour and no edge effects, use KENLAYER to determine for the two pavement systems given below:

a.  total maximum surface deflection of the pavement system;

b.  horizontal strain at the bottom of the HMA layer; and,

c.  vertical stress on the top of the subgrade.

Pavement systems:

i)  150 mm of HMA with 3,500 MPa modulus; placed directly on a sandy subgrade with 75 MPa modulus.

ii)  75 mm of HMA with 3,900 MPa; 200 mm of granular base with 150 MPa modulus; and clay subgrade with 40 MPa modulus.

2.) Assuming the HMA is the Asphalt Institute "standard mix", use both the Asphalt Institute and Shell methods (at 95% reliability) to predict the failure mode by either fatigue or rutting, and estimate the limiting number of load repetitions to achieve this failure mode for the two pavement systems described in Problem 1.

3.) Using the AASHTO method, design a flexible pavement system consisting of HMA and granular base placed on the subgrade described in Table 3.1 below, for the following conditions:

5-year predicted design traffic = W18 = 1.5(106) ESAL pt=1.8;R=95%;S0=0.35 Granular base modulus, E2 = K1-K2, where K1 = 7000 and K2 = 0.6 Base is expected to be exposed to moisture levels approaching saturation for 2% of the time.

Question 2:

Design a flexible pavement overlay using the AASHTO method for a 5-year old pavement structure consisting of 5.75 inches of HMA and 23 inches of granular base, placed on a silty clayey sand subgrade. The future traffic to be sustained over the next five years will be 2.1(106) ESAL.     Deflection testing conducted in October at a temperature of 68°F, using a load of 18 kips, provided a mean surface deflection of 0.191349 inches centred under the 5.9-inch radius loading plate and 0.022955 inches at a distance of 48 inches from the centre of the loading plate. Assume m2 = 1.10 due to contamination of the granular base with fines. Use p1 = 4.2, pt= 1.5, R=95% reliability and assume a standard deviation of 0.49.

Question 3: 

a)Using the PCA method, design the minimum slab thickness (to the nearest 1⁄2 inch) required for a 4-lane divided major highway (2 lanes in each direction separated by a grass median). Design a rigid concrete pavement with doweled joints and with concrete shoulders to be placed on a 9-inch thick untreated granular subbase which overlays a clay subgrade having a k-value of 100 pci. Modulus of rupture for the concrete is 650 psi. Design period = 20 years; current ADT is 13,500; annual growth rate is 3.5%; and ADTT = 20%.

b)Design the welded wire mesh reinforcement, tie bars, dowels and joints, and shoulders required if this pavement is to be a jointed reinforced concrete pavement with a lane width of 12 ft. Use a maximum allowable joint opening of 0.25 inches for a doweled joint.

Posted Date: 2/21/2013 5:22:06 AM | Location : United States







Related Discussions:- Aashto method, Assignment Help, Ask Question on Aashto method, Get Answer, Expert's Help, Aashto method Discussions

Write discussion on Aashto method
Your posts are moderated
Related Questions
Explain the "Standard Penetration Test" used in soil exploration. List the information that can be obtained by the test when made in (a) clay, (b) sand. Comment on the correctio

If you have never used an ice dam melting sock on your roof before, you will search that they give an inexpensive method for removing roof ice dams and improving your home's heatin

Explain in detail about  Textural classification. Sketch neatly the Casagrande's plasticity chart indicating several aspects. How would you use it in classifying the fine graine

(a) Explain the 'Soil Texture' and 'Soil structure'. What are the various terms used to explain the above properties of the soil? (b) A clay sample having natural moisture conte

Define the pre-tensioned concrete construction We understand that in the pre-tensioned concrete construction, stretched tendons are provided in the concrete moulds at the time

Need to know about compressive strength test and tensile strength test of cement

Ask questio #Minimum 100 words accepted# what is varigon theorem and what are their application ? its examples

The obstacles that the students of civil engineering face when it comes to produce a good piece of writing in English

Define the concept of Creep of Concrete Creep of concrete is another important characteristic. It represents progressive strains in concrete which occur at constant value of st

Explain Beam-Columns 1. A specific case of a beam subjected to:  Axial loading Strong axis flexural stress   2. The section is also pinned at both ends pe