Use of Aluminium Refinery Residue (Red Mud) as A Construction Material for Pavements

Abstract

A good road network connects remote places and also acts as a feeder system to the other modes of transportation. Manufacturing and the construction industries are in boom with the growing economy of the World. With the growing infrastructure, the demand for conventional construction materials is high, resulting in the depletion of natural resources. In recent days, pavements are subjected to excessive loads due to freight traffic, meanwhile, the depletion of conventional materials has forced people to shift towards alternate construction materials and researchers are in search of alternate materials which can provide the same strength as that of conventional materials. Therefore, waste materials from different industries are tested in laboratories by researchers to replace the natural materials in pavement constructions. Aluminium and steel are produced in very large quantities compared to other metals, these industries also produce the by-products that are either partially utilized or unutilized. Aluminium refinery residue (ARR) with its colour known as red mud, produced from bauxite by Bayer process, its high pH demands huge storage land. The steel and Iron Industries produce ground granulated blast furnace slag (GGBS) as a by-product. In road construction, a large quantity of material is required at the lower layers. In this present work, waste from both industries was used, GGBS makes complex compounds with sodium hydroxide and sodium silicate which increases the strength properties of ARR. The aluminium refinery residue was stabilized with 20, 25, 30% of GGBS, 3, 4, 5% of sodium oxide (Na2O) and silica modulus (Ms) of 0.5, 1.0,1.5 at fixed water to binder ratio 0.25. The compaction test was done on both the treated and untreated aluminium refinery residue to check the maximum dry density and optimum moisture content. The treated samples were cured (for 0,7,28 days) at room temperature. In case of stabilized ii aluminium refinery residue, the maximum strength was achieved at 25% of GGBS and alkali solution consisting of 4% Na2O and 1.0 Ms at both standard and modified Proctor densities. The stabilized aluminium refinery residue with 25% and 30% of GGBS and alkali solution consisting of 4 and 5% of Na2O having 1.0 and 1.5 Ms has passed durability test after 28 days of curing at both densities. The stabilized ARR with 25% of GGBS and alkali solution consisting of 4% of Na2O having Ms of 1.0 at both densities achieved the maximum flexural strength, fatigue life, and the densified structure. The formation of calcium-silicate hydrate and calcium aluminosilicate hydrate structures resulted in a remarkable improvement of compressive strength, flexural strength and fatigue life of the stabilized samples due to the dissolved calcium ions from GGBS, and silicate and aluminium ions from alkali solutions. The design of roads was done by replacing the conventional granular layer with the durable stabilized ARR based on Indian standard codes and the thickness of pavement with stabilised ARR was lesser than the conventional pavement layer. Stress-strain analysis was carried out using IITPAVE software and found that stresses were within the limit. The cost comparison of the pavement made with conventional material and with the proposed GGBS stabilized ARR was carried out and the cost of stabilised pavement layer was nearly same as that of the conventional pavement layer.