Highway Research Record

VI. RESEARCH WORK DONE IN ACADEMIC INSTITUTIONS RELATED TO THESIS WORK
B. PAVEMENT ENGINEERING AND PAVING MATERIALS
A Study on Cost Effectiveness of Stabilized Fly ash for Rural Road Construction

Date of Start:July 2004 to December 2004
National Institute of Technology, Tiruchirappalli (R, S)

Scope and Objective
(i) To determine the best activators and their optimum dosages
(ii) To compare the cost effectiveness of rural road construction in the following conditions
      • Flyash with 50% of sand
      • Flyash with optimum dosage of lime
      • Flyash with optimum dosage of both lime and sand

Methodology
(i) To determine the Geotechnical properties of flyash and sand
(ii) To stabilize the flyash with sand(10%,20%,30%,40%,50%) and to observe the changes in its proctor’s density and CBR     values
(iii) To stabilize the flyash with lime(0.5%,1.0%,1.5%,2%,2.5%) and to observe the changes in its proctor’s density and CBR      values
(iv) To identify the optimum lime content (OLC) based on Proctor’s density test
(v) To stabilize the flyash with OLC and sand(10%,20%,30%,40%,50%) and to observe the changes in its proctor’s density      and CBR values
(vi) To identify the optimum dosage of both lime and sand called desired activator
(vii) To design the pavement based on SP20-2002 “Rural road manual” in the fallowing conditions
      • Flyash with 50% of sand
      • Flyash with optimum dosage of lime
      • Flyash with desired activator
(viii) To find the cost of road in the fallowing conditions
      • Road embankment with existing subgrade
      • Road embankment with stabilized flyash by using 50% sand
      • Road embankment with stabilized flyash by using optimum dosage of lime
      • Road embankment with stabilized flyash by using desired activator

Findings and Conclusions

(i) CBR value of flyash is increased to 9.3% with addition of 50% sand over its initial value 3.2%
(ii) Optimum lime content of flyash occurred at 1.5% with dry density 12.8 KN/m3 and CBR value 9.4%
(iii) Maximum value of CBR (13.3%) is obtained when the flyash is mixed with desired activator (OLC+20%sand)
(iv) Pavement thickness over embankment with stabilized flyash by using 50% sand, OLC and desired activator are 260mm,       259mm and 220mm respectively
(v) Saving cost of Rural Road construction with stabilized flyash with 50% sand, OLC and desired activator are 6%,25.3% and      20.3% respectively
(vi) The CBR value of flyash stabilized with 40% of sand is nearly same as that of sand. It means that from this combination       onward the mix starts behaving like sand
(vii) Increased rate of CBR value of flyash stabilized with lime is more than with sand
(viii) Flyash with OLC and “Lime Sand Stabilized Flyash” can be used economically for rural road construction
(ix) As per drainage and leaching point of view flyash with desired activator will give good results