Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

Fiber reinforced aerated lightweight concrete (FALC) was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of expanded clay. A self-compaction agent was used to reduce the water-cement ratio and keep good workability. A surfactant was also added to introduce air into the concrete. This study provides basic information regarding the mechanical properties of FALC and compares FALC with fiber reinforced lightweight concrete. The properties investigated include the unit weight, uniaxial compressive strength, modulus of elasticity, and toughness index. Based on the properties, a stress-strain prediction model was proposed. It was demonstrated that the proposed model accurately predicts the stress-strain behavior of FALC. 1. Introduction In the last three decades, prefabrication has been applied to small housing and tall building construction, and precast concrete panels have become one of the widely used materials in construction system. Recently, much attention has been directed toward the use of lightweight concrete for precast concrete to improve the performances, such as dead load reduction, fire resistance, and thermal conductivity, of the buildings. Additionally, the structure of a precast building should be able to resist impact loading cases, particularly earthquakes, since resisting earthquakes of these buildings under the performances is becoming an important consideration [1, 2]. Many efforts have been applied toward developing high performance concrete for building structures with enhanced performance and safety. Various types of precast concrete products, such as autoclaved aerated lightweight concrete (AALC), fiber reinforced concrete (FRC), and lightweight concrete, have been developed and experimentally verified. A number of them have been applied in full-scale building structures. AALC is well known and widely accepted, but its small size and weak strength limit its use in structural elements [3]. Lightweight aggregate concretes offer strength, dead load reduction, and thermal conductivity, but their limited ability to absorb earthquake energy raises concerns. In contrast, FRC has greater energy-absorbing ability, which is called “ductility or inelastic