Some of Mechanical Properties of Lightweight Aggregate Concrete Reinforced by CarbonFiber and Modified by Acrylic Polymer

Abstract

Lightweight aggregate concrete(LWAC) is usually chosen for structural purposes where its use will lead to a lower overall cost of structure than would be expected with normal weight concrete. Recently, very limited amount of study related to investigating the properties of concrete reinforced with chopped carbon fiber has been done .Therefore the effect of chopped carbon fiber on the mechanical properties of LWAC is investigated in this study. The effect of adding acrylic polymer on the mechanical properties LWAC reinforced with chopped carbon fibers also was studied in this research. The experimental program consists of making seven mixes,one represented the reference mix and three mixes containing different volume fractions of ( 0.5%,1% and1.5%) of chopped carbon fiber .Polymer was added in three polymer cement ratios p/c of 3% , 7% and 10% to the mixof the optimum chopped carbon fiber, which was 1% in this work. The specimens is prepared one hundred twenty six (100×100×100)mm cubes for compressive strength, density , dry density ,absorption and ultrasonic pulse velocity, eighty four (100×200)mm cylinder for splitting tensile strength and fifty six (100×100×500)mm prisms for flexural strength. Hence, the experimental program included all mixes at (7,14,28and56) days standard tests specimens. The results showed that the addition of carbon fiber improves the mechanical properties of LWAC . The addition of carbon fibers causes an increase in compressive,splitting tensile and flexural strengths relative to the reference LWAC (without fiber). The compressive strength increased about 30%, splitting tensile strength increased about 58% and flexural strength increased about 35%. The dry density and water absorption was decreased about6% and 70% respectively. Ultrasonic pulse velocity decreased about 18%. While adding acrylic polymer to LWAC reinforced with chopped carbon fiber has a negative action on the mechanical properties, if it was compared to the mix of 1% chopped carbon fiber. Where the compressive, splitting tensile and flexural strengths decreased about 16%, 7% and 30% respectively. The dry density and water absorption was increased about1% and 25% respectively. Ultrasonic pulse velocity remains as it is.