Highway Research Record

Use of Overburnt Brick Aggregates in Pavement Construction

Date of Start:June 2004
Indian Institute of Technology, Kharagpur (S, I)

Scope and Objective
The work includes study of possibility of using brick aggregate as a sub-base material in both flexible pavement in combination with soil and rigid pavement as aggregate in lean cement concrete base.

(i) To investigate the possibility of using brick in sub-grade improvement and in sub-base.
(ii) To determine CBR of mixture of soil and brick in different proportions at the proctor density.
(iii) To determine resilient Modulus of over burnt brick aggregate and over burnt brick aggregate soil mixtures.
(iv) To study feasibility of using brick aggregates in lean cement concrete i.e. to find out the best mix which will give      acceptable strength for use as road base and sub-base based on its compressive strength, modulus of rupture, and fatigue      life.

Findings and Conclusions
(i) In case of CBR test with mix of over burnt brick and soil, there was hardly any increase in the CBR value when brick content      is less than 25 %. CBR value of soil and over-burnt mixture was found higher than the soil and ordinary brick mixture.
(ii) Soil and over burnt aggregate mixture with brick aggregate content more than 50 percent satisfies the criterion for sub     base material of CBR value 30( MORT&H).
(iii) In case of tri axial test, Resilient Modulus value achieved for standard proctor and modified proctor density for over burnt      brick aggregate and 50 percent soil is very low. So, only over-burnt Brick (modified proctor density) and over burnt Brick      and soil (25%) at modified proctor density was chosen for the design of rural flexible pavements.
(iv) The relationship of M.R and compressive Strength of may not be applicable.
(v) The compressive strength obtained by the mix of over burnt brick and cement is of reasonable strength except for the mix      of 1:15 (cement to aggregate ratio) where compressive strength is less than 5 MPa.
(vi) There is a considerable increase in modulus of rupture value for mixes with over burnt brick aggregate as compared to mix      with ordinary brick aggregate. For 1:11.5 mix the modulus of rupture value increased from 1.45 MPa to 2.26 MPa , an      increase by 55.8 percent.
(vii) The flexural fatigue test result almost coincides with the result given by S.F.Brown. Good linear correlation exists between       fatigue life and stress ratio.
(viii) Combining the result of three mixes considered for over burnt brick aggregate derived a single equation. The combined        equation may be used for design purpose using lean cement base with over burnt brick aggregate.
(ix) It is found that when bituminous layer is considered, the reduction in the base thickness is significant. Therefore a       bituminous surface provided, it will not only ensure durability but also good riding surface.