Recycled Waste Powders for Alkali-Activated Paving Blocks for Urban Pavements: A Full Laboratory Characterization

Abstract

Paving blocks are today a popular paving solution for urban surfaces. Considering the wide variety of products currently on the market, it is possible to build pavements that differ in terms of functionality, bearing capacity, skid resistance, visual impact, and aesthetic integration with the surrounding landscape. Interlocking concrete paving block is the most common construction technology considering its low cost and its easy installation. Different wastes and second-hand materials have recently been tested in order to completely or partially replace the raw materials used for the production of paving blocks. In this paper, a waste basalt powder is used for the production of alternative paving blocks through the alkali-activation process. Two different synthetic blocks were produced, with and without aggregates. Taking into account the EN 1338 standard for concrete paving blocks, a complete laboratory characterization is proposed for the two experimental blocks. Tests highlighted positive results and downsides that need to be optimized in order to convert the laboratory production to an industrial scale.Infrastructures 2019, 4, 73 2 of 13 have a large applicability in civil constructions [14]. The most common paving blocks are produced in cement concrete, where the mix design is a function of the final performance required for the block. Lightweight concrete is often used for pedestrian and outdoor pavements. Porous concrete is generally required for permeable pavements (i.e., parking areas) and high-performance cement concrete is suitable for heavy load traffic pavements or heavy load storage areas [15][16][17][18].According to the latest estimates, the constructions sector is responsible for 36% of global energy use and around 40% of CO2 emissions [19]. Taking into account the growing interest for environmental issues such as the limitation of non-renewable resources and the emission of greenhouse gasses related to human activities, the construction's sector has been strongly affected by eco-friendly policies. In the last years, an increasing demand for alternative and sustainable materials has been registered to promote and to develop the so-called novel "green constructions" [20][21][22][23]. The recycling of waste materials seems to be a viable solution for the production of new construction materials. The re-uses of wastes, industrial byproducts and second-hand materials can couple the advantages given by the conservation of resources to the inclusion of materials destined for landfills in the production cycle of a new product [24]. This approach is perfectly in line with the circular economy concept, where the objective is the reduction of the environmental footprint, also related to the construction's sector. Furthermore, when scientifically proven, the re-use of waste materials does not compromise the construction standards [25,26]. Thus, researchers from all over the world are focusing on experimental applications of wastes as construction materials, being the recycling the new frontier of the civil ...

Quarry Waste as Precursors in Geopolymers for Civil Engineering Applications: A Decade in Review

“…Waste basalt powder has been used for producing geopolymer bricks and artificial lightweight aggregates. Different ratios of sodium hydroxide and silicates were mixed with MK and basalt powder [95]. A liquid to solid ratio of 0.75 and curing of 24 h at 70 • C achieved the highest compressive strength of 64 MPa.…”

“…Only sodium silicate with different concentrations was used by Falah et al [108], whereas Paiva et al [43] used a combination of sodium silicate and 10 M sodium hydroxide as activators. Similar activator content of SS and 10 M NaOH was used for producing lightweight aggregates and paving blocks using basalt powders and MK as precursors [27,95]. With very similar curing conditions, only basalt was activated using NaOH for the production of microcrystalline particles [96].…”

“…With very similar curing conditions, only basalt was activated using NaOH for the production of microcrystalline particles [96]. Samples that benefitted from MK and a combination of both SS and SH [27,95] presented higher compressive strength.…”

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

“…Transforming quarry dust/waste into secondary materials could give a second chance to waste materials, contribute to waste management, balance natural resource utilization and produce a circular economy for the construction sector [ 23 , 24 , 25 , 26 ]. Thus, the current research focused on producing cement mortars by substituting natural sand with the waste silt obtained from limestone aggregate production S.A.P.A.B.A.…”

Special Issue: Recent Advances and Future Trends in Pavement Engineering

“…These are commonly employed as paving solutions due to the relatively low production and laying costs. Tataranni [3] suggested the use of a waste basalt powder to produce alternative paving blocks through the alkali-activation process. The production of paving blocks through the alkali-activation of waste basalt powder seemed to be a viable alternative for interlocking modular elements.…”