ISSN: 1813-0410

Keywords : Rigid Pavement

Performance Evaluation of Modified Concrete Layer by Sodium Silicate in Rigid Highway Pavement

Fatimah Fahem Al-khafaji

journal of kerbala university, Volume 10, Issue 4, Pages 203-218

The using of conventional concrete mix in rigid pavement causes costly layer with high maintenance requirement . It is necessary to use additive materials in pavement construction as modifiers which could improves the performance of concrete layer .
The major objective of this research is to evaluate the mixing a locally additive on performance of concrete layer in rigid pavement by using sulfate-resisting cement (type V) produced in Iraq . The additive represented by soluble Sodium Silicate also known as " water glass " .
Concrete mixture specimen have been prepared with coarse aggregate of maximum size (50)mm and fine aggregate of maximum size (9.5)mm . Soluble Sodium Silicate has been used as an additive with the percentages (5 , 10 , 15) % by weight of cement . The performance of concrete mixture is evaluated using strength tests i.e (compressive and flexural) as well as thermal test (coefficient of thermal expansion) .
Results of using such modified concrete mixture show that compressive strength and modulus of rupture are decreased by (1.14 , 1.06) time at 7 days and increased by (1.17 , 1.16) time at 28 days respectively as compared with control mix . The results of coefficient of thermal expansion are decreased by (1.12) times at 28 days when compared with control mix . However, percent of 10% soluble Sodium Silicate in concrete mix shows better performance of concrete pavement corresponding for both strength and thermal properties . This percentage was adopted for all above mentioned comparison . The use of modified concrete mix has significant effect on the thickness design and joint spacing of main layer in rigid pavement .

Development of a Computer Program for Rigid Pavement Slab Thickness Design

Mohammed Abbas Hasan Al-Jumaily; Firas Hasan Alwan Asad

journal of kerbala university, Volume 4, Issue 1, Pages 91-105

This paper focused on building a VBasic computer program for Concrete Pavement thickness Design coded as (CONPVD-93). This thickness design utility solves the 1993 AASHTO Guide basic design equation for rigid pavements. It also supplies some basic information on variable descriptions, typical values and equation precautions. CONPVD present both a direct and detailed thickness design process .In detailed mode the step- by- step calculations can be seen in CONPVD desing process.Three options for calculating the predicted ESAL applications namely direct,axle load equivalency facter ALEF-based ,and truck factor TF- based calculations, were presented.To account the composite K- modulus for the presence of rigid footing, a new model has been developed in this study. Seasonal effect was adopted in computing the effective modulus of subgrade reactions. The effect of different values for proposed slab thickness on the final results has been thoroughly studied also. CONPVD has proven very useful as an effective educational tool as well as a powerful design tool.