Characteristic of Polymeric Lightweight Aggregate with Coal Fly Ash and Epoxy Resin for Manufacturing the Lightweight Concrete

Abstract

Concrete is an essential element and is widely used in various industrial construction works. However, concrete is weak in its specific gravity range of 2200 – 2500 kg/m³. Using lightweight aggregates is one way to reduce the weight of concrete. In Indonesia, the availability of coal fly-ash (CFA) is easy to obtain and abundant, while the utilization rate is still low. To overcome this problem, CFA mixed with epoxy resin (ER) is used as a binder to manufacture polymer lightweight aggregates (PLA). The manufacturing process uses a simple mixing method using three different compositions. The ratio composition of coal fly-ash and epoxy resin proposed in this study are 90:10 (PLA_90:10), 80:20 (PLA_80:20), and 70:30 (PLA_70:30). From the results of testing the compressive strength and specific gravity of the three aggregate compositions, it was found that PLA_70:30 had a compressive strength of 74.60 MPa and a specific gravity of 1668 kg/m³ at an aggregate age of 28 days. The aggregate microstructure is shown by scanning electron microscope (SEM) photo of each composition. The greater the composition of the epoxy resin on the lightweight polymer aggregate, the better the bond between the aggregate particles. The coal fly-ash is improperly bound and the aggregate becomes more fragile when there is less epoxy resin used. Furthermore, PLA_70:30 aggregate, which has become crushed aggregate, is inserted into a lightweight concrete mixture with a design quality of f'c = 17.5 MPa, following the requirements for lightweight concrete quality. The result is lightweight concrete with a compressive strength of 18.38 at 28 days, and specific gravity that varies between 1918.87 kg/m³ - 1928.93 kg/m³. According to the ASTM, the results of the compressive strength and specific gravity tests show that PLA_70:30 meets the standards specified as lightweight aggregates for lightweight structural concrete.