Use of fibres and surface treatment to improve the durability of concrete affected by sulphide mining

Abstract

The aim of this research is to evaluate solutions to improve the durability of structural concrete used in sulphide mining. This type of environment is one of the most aggressive conditions in which a concrete structure can be placed, with pH values below 3 and high sulphate contents. These environments cause significant degradation of metallic and structural materials, resulting in mass loss and alteration of mechanical properties, a process that is accelerated by the intervention of acidophilic bacteria. In this work it is proposed to reinforce the concrete by incorporating polypropylene fibres and silica fume and to protect the specimens by applying two types of surface materials, one polyurethane base and the other asphalt base. Several laboratory tests were carried out to evaluate the fundamental mechanical properties and durability of concrete, including tensile and compressive strength tests In addition, Slake tests were carried out to analyse the degradation of different fragments, water permeability tests and pressure sandblasting tests to measure the behaviour of the concrete against abrasion. The results confirm an increase in the tensile strength of fibre-reinforced concrete of about 8%, while the use of both types of surface materials has been shown a zero water penetration depth, while at the same time significantly improves the performance against impact degradation and abrasion with a reduction in weight loss that obtained in the reference samples with Slake test which is reduced to only 0.45% with surface treatment with polyurethane, 1.01% with asphaltic treatment and 2.48% with fibres, and even no weight loss in the sandblasting tests on the samples treated with asphalt material.