Bond Strength between Hybrid Fiber-Reinforced Lightweight Aggregate Concrete Substrate and Self-Compacting Concrete as Topping Layer

Slamet Widodo

doi:10.1155/2017/7015254

Abstract

Structural performance evaluation of composite concrete slabs that were constructed using partially precast concreting system which utilized Hybrid Fiber-Reinforced Lightweight Aggregate Concrete (HyFRLWAC) as stay in-place formwork and self-compacting concrete (SCC) as topping layer was conducted in this research. This paper focused on determining the appropriate strength limit criteria of interface between two different concrete layers. The tensile strength was tested using pull-off test, while concrete cohesion was investigated based on modified bisurface shear test, and dual L-shaped shear test was used to determine the effect of normal force on the shear strength of concrete interface. Sample variants were designed based on the substrate surface conditions, compressive strength of the topping layer, and magnitude of perpendicular normal force acting on interface area. The substrate surfaces were prepared in as-placed and grooved conditions for tensile test, cohesion, and shear strength test. Test results indicate that tensile strength, cohesion, and shear strength of the concrete interface are affected by surface condition of the substrate, compressive strength of the topping layer, and the normal force acting perpendicularly on the concrete interface area. Proposed formulation for bond strength prediction between HyFRLWAC as substrate and SCC as topping layer is also presented in this paper.

Highlights

Composite concrete construction can be found in application of partial depth precast concrete construction, in which the precast concrete is used as stay in-place formwork while cast in-place concrete is used for topping layer
Test results indicate that the compressive strength of self-compacting concrete (SCC) that was used as topping layer on the lightweight aggregate concrete type of substrate layer will affect the interfacial tensile strength
Based on the test results in this research, it can be concluded that the surface roughness of the concrete substrate and compressive strength of topping concrete layer significantly affect the tensile strength of concrete interface

Summary

Introduction

Composite concrete structures are widely implemented for construction works in accordance with the rapid development of concrete construction industry. In this technique, it can be observed that the crosssection of this structural element consists of two concrete layers or more, and each layer of concrete has different physical or mechanical characteristics. Composite concrete construction can be found in application of partial depth precast concrete construction, in which the precast concrete is used as stay in-place formwork while cast in-place concrete is used for topping layer. The expected benefits from the application of partially precast concrete systems include saving cost component for formwork and scaffolding as well as labor costs, better quality control, faster construction period, and minimizing the weather constraints during the implementation of construction works

Objectives

Results

Conclusion