Determination of fracture characteristics for local rigid pavement materials in Iraq

الملخص EN

This paper presents an experimental method using (TPBT) Three Point Bending Test to identify fracture parameters and performance of concrete rigid pavements such as (KI, KIC, J-Integral and GF).

To achieve these objectives and to conduct the experimental part of this study, two concrete mixtures developed (Mix No.1 and Mix No.2) from local available materials are used which include: Iraqi Portland cement (Tasloja) resistant to sulphates, coarse aggregate gradation with a maximum sizes of (25) mm for Mix No.1 according to AASHTO M 43, Size No.

67grade type and maximum size of (19) mm, river sand as a fine aggregate, and water.12 concrete beam specimens are subjected to two loading rates (0.45kN/s and 0.75kN/s) to reflect the interaction with different traffic loading and different crack depths (0,15%,30%) of specimen depths are used to simulate the initial crack depth in rigid pavement.

Experimental results show that, the maximum loading for fracture increased with the increased in loading rate for (Mix No.1) and (Mix No.2).

The deflection for No.1 presents higher deflection results than Mix No.2 and these results give an indication that (Mix No.1) is more flexible than Mix No.2 under different loading rates and other conditions.

The results show that, maximum load at failure and deflection decrease with the increase in notch depth.

The results show that, the value of stress intensity factors (KI) and Fracture Toughness (KIc) increased with the increasing in the rate of loading and decrease with the increase in the notch depth.

Furthermore, the results show that, the Fracture Toughness values (KIC) for Mix No.1 and Mix No.2 reach to (0.675 and 0.640MPa√m)2 respectively.

The results of J- integral show that, the effects of notch depth and mix proportions on the value of rigid pavement are significant if compared with loading rate.

Finally the results of fracture energy show that, the effects of notch depth and loading rate test on the fracture energy are significant if compared with mix proportion.