Mechanical Microstructure of Concrete Containing Nano silica and Natural fibers to Improve the properties of Recycled Aggregate Concrete

Abstract

This research focuses on mechanical properties development and microstructure of Recycled Concrete Aggregate (RCA) using nano silica and natural fibers. Sisal fibers and palm oil fibers used to replace fine aggregate; Recycled Concrete Aggregate used to replace Natural Concrete Aggregate (NCA) and nano silica used to replace Portland cement type 1 (OPC). The water to binder (W/B) ratios were 0.60 by weight. The concrete containing nano silica and Natural aggregate had the highest compressive strength of 201.80 ksc at 7 days and 308.25 ksc at 28 days, according to the compressive strength and flexural strength tests at 7 days and 28 days. The flexural strength of concrete containing recycled aggregate and palm oil fibers had maximum value of 45.90 ksc after 28 days. Scanning Electron Microscope (SEM) investigation of the microstructure of recycled aggregate concrete revealed that concrete containing natural fibers is less homogenous. When a gap appears, which corresponds to the compressive test results.