Black Liquor Waste Produced from Bagasse Kraft Pulping as an Admixture in Concrete

Abstract

The black liquor (BL) that obtained as a by-product of pulp and paper manufacturing process after digestion step, where the cellulose fibers have been removed from the bagasse, is one of such material that can be used as a chemical admixture. Annually, around two million tons of bagasse Kraft black liquor (BKBL) with 6:8wt% total dissolved solids (TDS) are produced in Egypt. The discharge of black liquor to water resources causes serious of environmental issues in contrast with adding it to concrete as an admixture has a positive impact on environment beside economy. Adding of BL to concrete improves its properties such as workability, compressive strength and setting time (initial and final). In this study BKBL is added to fresh concrete at different concentrations (0, 1, 2, 3, 4%), the concrete is then tested for bulk density, apparent porosity, setting time, workability (slump test), and the compressive strength. The results showed that mixing of concrete with BKBL up to 4 wt% has a positive effect on compressive. The initial and final setting times were increased by adding black liquor, so it can be used as a retarder. Adding of 2 wt% of BKBL is the recommended value that gives optimum improved results. These results open the door for utilization of black liquor from Qena Paper Industry Company, Quse, Egypt as an admixture to improve concrete properties.