The construction sector could provide solutions for the safe utilization of industrial by-products as construction materials, if proper characterization and control of the materials properties is undertaken. Under this consideration, fines produced from marble cutting and fines produced from concrete truck washing were investigated as fine material for use in cement mortars. Both these by-products are produced in large amounts in the form of sludge. Marble Sludge Fines (MSF) and Cement Sludge Fines (CSF) were characterized in terms of fineness, density, chemical analysis and suitability for use with cement. Mortars with variable rate (10%, 20% and 30%) of cement substitution with MSF or CSF were tested and compared to a reference cement mortar in respect to their fresh and hardened properties. Packing ability and viscosity were measured in fresh mortars, while strength development, water absorption and porosity were measured in hardened mortars. The results confirm the suitability of both as filler material; although MSF performed better regarding fresh mortar properties and CSF showed better results regarding strength development.

Introduction

By-products from industrial processes are being produced in large amounts around the world and their handling, processing and disposal is taking up considerable effort and increasing financial and environmental cost [1,2]. It is estimated that the amount of waste generated during cutting, sawing and shaping of ornamental marble accounts for 20–۲۵% of the total marble processed [3], resulting in huge amounts of marble waste. Marble waste is either produced as large pieces that are left over in primary cutting, which find various uses as aggregates [4,5]; or as fine material produced in wet condition from sawing and shaping, named marble powder, marble dust or marble sludge fines (MSF), which is being investigated as filler for construction applications [6–۸]. Concrete production, on the other hand, is also generating large amounts of waste; depending on local practices, it is estimated that 1 9% of fresh concrete is returned to the concrete batching plant [9]. This accounts for huge amounts of waste as the annual global consumption of concrete exceeds 10 billion tons [10].