Preliminary Evaluation of Cement Mortars Containing Waste Silt Optimized with the Design of Experiments Method

Abstract

Every year, up to 3 billion tons of non-renewable natural aggregates are demanded by the construction sector and approximately 623 million tons of waste (mining and quarrying) was produced in 2018. Global efforts have been made to reduce the number of virgin aggregates used for construction and infrastructure sectors. According to the revised waste framework directive in Europe, recycling at least 70% of construction and demolition waste materials by 2020 was obligatory for all member states. Nonetheless, quarries must work at full capacity to keep up with the demands, which has made quarry/mining waste management an important aspect during the past decades. Amongst the various recycling methods, quarry waste can be included in cement mortar mixtures. Thus, the current research focuses on producing cement mortars by partially substituting natural sand with the waste silt obtained from the limestone aggregate production in S.A.P.A.B.A. s.r.l. (Italy). A Design of Experiments (DOE) method is proposed to define the optimum mix design, aiming to include waste silt in cement mortar mixtures without affecting the final performance. Three cement mortar beams were produced and tested for each of the 49 randomized mixtures defined by the DOE method. The obtained results validate the design approach and suggest the possibility of substituting up to 20% of natural sand with waste silt in cement mortar mixtures.

Thermally Treated Waste Silt as Filler in Geopolymer Cement

“… The washed-off silt during limestone production is stored at S.A.P.A.B.A. s.r.l.’s sedimentation lakes, where it is collected and processed for further use [ 6 ]. …”

“…Different methods and approaches have been developed over the past few years to reduce the undesirable impact of quarry waste on the environment. For instance, quarry waste has been used in cement mortars [ 4 , 5 , 6 ] and asphalt pavements [ 7 , 8 , 9 ]. A different approach includes recycling mineral fillers and quarry dust in geopolymer cement production [ 10 , 11 , 12 , 13 , 14 ].…”

A Review on Acoustic and Skid Resistance Solutions for Road Pavements

“…In fact, those materials can be produced with specific waste powders generated from different industrial processes (e.g., mining, milling, sawing, and washing) and transformed into castable construction elements, including engineered aggregates. Indeed, recent and ongoing studies on the use of geopolymers or Alkali-Activated Mixtures (AAM) for the production of aggregates and mixtures are promising [67,[82][83][84]. Nonetheless, with respect to their use in HiFASPs and other severe wearing surface conditions, additional research must be conducted to guarantee their durability, recyclability, and avoid any potential environmental impact.…”

Mixture Optimization of Concrete Paving Blocks Containing Waste Silt

“…Recycling such material is of paramount importance since it could reduce the adverse environmental impacts due to landfills. These kinds of materials have been used in the production of several products, such as geopolymers, cement mortars, artificial aggregates, and pavements [1][2][3][4][5][6][7].…”