Physical and Mechanical Properties of Mortar Mixed with Paper Mill Waste

Abstract

The industrial and construction sectors are experiencing continuous growth each year. Concrete, which is used as the main material in construction, is composed of cement, aggregate and water. Research on mortar and aggregate is carried out to create concrete according to the required specifications of certain buildings. However, 8% of global carbon dioxide emissions come from the cement manufacturing process which is one of the main materials in mortar. In the industrial sector, the paper industry is one of the top producers of waste, approximately 48 tonnes for every 100 tonnes of pulp produced. The main wastes of this industry include slaker grits, dregs, lime mud and fly ash which only end up in landfill. To address this problem, this research investigates the modification of mortar mix materials by utilising paper mill waste. Specifically, fly ash and grits are used as substitute for cement and fine aggregate, respectively. Results indicate that the density value of concrete decreased with the increase of fly ash mixture, and the compressive strength value of mortar with varying additions of 0%, 10%, 20%, 30%, 40% and 50% fly ash reached 7.42, 6.68, 6.18, 4.97, 3.93 and 2.97 MPa. The decrease in density and compressive strength with increasing fly ash content can be attributed to the lower adhesive power of waste compared to cement owing to its lower lime oxide content. The value of compressive strength samples 1, 2 and 3 belong to the N type, which can be used as load-bearing walls, while samples 4, 5 and 6 fall into the O type, which can be used as non-load-bearing and decorative walls in accordance with SNI 03-6882-2014 standards.