Evaluation of Solidified Wastewater Treatment Sludge as a Potential SCM in Pervious Concrete Pavements

Abstract

Waste and recycled materials have recently been used in the construction industry to comply with the principles of circular economy and sustainable development. The aim of this paper is to examine the potentials of solidified wastewater treatment sludge (SWWTS) as a supplementary cementitious material (SCM) in the production of lightweight pervious concrete pavers (LWPCP) suitable for pedestrian trails and rooftops (green) that comply with EU standards. Detailed characterization of SWWTS was performed, in order to understand its properties related to application as SCM, which led to the conclusion that it may be applied only as a filler, having 89.5% of Ca(OH)2. After thorough characterization, LWPCP samples were prepared and testing of physical and mechanical properties was conducted. The research showed that partial replacement of cement with SWWTS led to the decrease of all mechanical properties, ranging between 3.91 and 5.81 MPa for compressive strength and 0.97 to 1.23 MPa for flexural strength. However, all of the investigated mixtures showed a value higher than 3.5 MPa, which was defined as the lowest compressive strength in the range of pervious concrete properties. The addition of SWWTS led to a slight decrease in bulk density of the mixtures and an increase in water absorption. This could be explained by the reduction in hydration products that would fill in the micropores of the matrix, since SWWTS showed no pozzolanic reactivity. Pore sizes that prevail in the tested binder matrices are in accordance with the results measured on ordinary pervious concrete (the largest fraction of pores had a diameter between 0.02 and 0.2 μm). Low thermal conductivity nominates produced pavers as potential rooftop elements.

Utilization of solidified industrial hazardous waste in construction: A case study

“…In addition, compressive strength values were still higher than in the case of some other concrete mixtures based on industrial waste (e.g. fly ash [14] and solidified wastewater treatment sludge [30]).…”

“…along with the compressive strength of some tested materials obtained from industrial waste. [14] 4.5 -17.5 Concrete with alum sludge (treated in a furnace at 200 °C) [29] 24.0 -48.0 Concrete with Lime Stone [29] 33.0 -53.0 Concrete with quarry dust [29] 36.0 -65.0 Concrete with solidified wastewater treatment sludge [30] 3.9 -5.8…”

A Novel Semi‐Analytical (Inertial) Solution for Determining Permeability of Highly Pervious Porous Materials Using the Two‐Reservoir Laboratory Setup

“…According to Govedarica et al. (2022), the porosity of these four samples varies between 0.35 and 0.38. For more details on this material see the aforementioned study.…”

“…The pavers, whose dimensions are given in Table 1, are made of lightweight aggregate of expanded clay particles (fraction 1-4 mm), cement CEM I 52.5 R used as a binder which is substituted with a solidified wastewater treatment sludge (SWWTS) to a certain extent (see Table 1), and water. According to Govedarica et al (2022), the porosity of these four samples varies between 0.35 and 0.38. For more details on this material see the aforementioned study.…”

Effect of the Dry-Wet Cycle on the Performance of Marine Waste Silt Solidified by Calcium Carbide Residue and Plant Ash

“…As a result, low-carbon and green strategies are crucial for the sustainable development of the stabilized agent industry [17]. In this respect, using various types of solid wastes as industrial waste and agricultural waste to substitute for high carbon-emission stabilized agents, such as lime, Portland cement, or their compound types, was considered a fairly effective strategy [18,19].…”