INFLUENCE OF AGGREGATE SIZE AND SURFACE ROUGHNESS ON INTERFACIAL BEHAVIOUR

The surface roughness (R_a) of three types of cylindrical aggregates (sandstone, limestone and granite) was measured by the Talysurf apparatus. It was found that the sandstone aggregate had the highest surface roughness, followed by limestone and granite. Interfacial bond strength between cylindrical aggregates and mortar matrix was determined experimentally using push-out specimens and predicted theoretically using two different approaches. In the first, the cylindrical aggregates were assumed to have an ideally smooth surface and as a result they had constant radius, r₀ over the aggregate length, L. In the second approach, the surface roughness of the aggregates was taken into account so that the radius, r was varied as a function of x, (0 ≤ x ≥ L). Hence, the influence of the surface roughness of the aggregates on the interfacial bond strength was revealed. It is found that the surface roughness plays a significant role in defining the interfacial bond strength in particular of smaller size aggregates. The effect, however, diminishes as the aggregate size increases regardless of the aggregate type.

• INTRODUCTION

• MATERIALS AND SPECIMENS

• MEASUREMENT OF SURFACE ROUGHNESS

• AGGREGATE PUSH-OUT TEST

• DATA REPRESENTATION BY FOURIER SERIES

• MATHEMATICAL MODELLING OF AGGREGATE PUSH-OUT

• RESULTS AND DISCUSSION

• CONCLUSIONS

• REFERENCES