Feasibility of Using Calcined Water Treatment Sludge in Rendering Mortars: A Technical and Sustainable Approach

Abstract

Many current industrial processes, such as water treatment, produce large amounts of waste. The water treatment sludge (WTS) must be properly disposed of and/or used as raw material for application in other sectors, such as the construction industry. The rendering mortar production can be an environmentally friendly alternative to recycle the WTS, this being the object of this research. In this way, mortars were produced with 2.5%, 5%, 7.5%, and 10% calcined WTS to replace natural sand. The water absorption, compressive strength, bond strength, and flexural strength properties were evaluated. A natural carbonation was carried out for the determination of CO2 uptake due to carbonation. The results showed that the incorporation of calcined WTS has an influence on all the properties evaluated. Considering 50 years of service life, the CO2 uptake potential for mortar with 10% calcined sludge WTP is 111 kg CO2/t. In the sustainability approach, it was observed that CO2 uptake due to carbonation is higher in mortars with the addition of WTS, and could be an environmentally friendly alternative that compensates emissions from the cementitious materials production.

Evaluation of tire rubber surface pre-treatment and silica fume on physical-mechanical behavior and microstructural properties of concrete

“…Many investigations have been conducted about the use of wastes in cement based materials, like the construction and demolition waste (CDW) (Silva and Andrade, 2017), granite residue (Sharma et al, 2017), siderite residue (Esen and Do gan, 2017), limonite residue (Esen and Do gan, 2018) and water treatment sludge (WTS) (Andrade et al, 2019). At the same time, another waste investigated today is the use of rubber from tire waste.…”

Performance of Mortar Incorporating Heat-Treated Drinking Water Treatment Sludge as a Silica-Sand Replacement

“…However, water consumption can be reduced as a result of the usage of some mineral admixtures, such as fly ash, which are known to have the opposite effect [20]. Moreover, Samples with sludge content showed a higher increase in the rate of water absorption at 90 days of curing, mostly indicating a slow rate of hydration through the pozzolanic reaction [27].…”

“…The increase was 1.5% and 3% for compressive strengths, 2% and 5% for flexural strength in 90 days of curing for 5% and 10% of sludge replacement, respectively. This improvement in compressive and flexural strengths 90 days of curing age is due to the matrix of the high porosity of the sludge, resulting in more water to be absorbed, which affects the hydration process during the time, the relatively high reactivity of sludge caused by the high content of CaO and amorphous silica, and also the late development rate of pozzolanic reactivity in the incinerated sludge composition [21,29], which takes more time for hydration process to be completed to form compounds possessing ,binding properties [18,27]. These findings confirmed the results of Li et al [19], in which mortars of 5% sand replacement with 900 o C heat-treated sludge showed higher compressive strengths for all curing ages as reference mortars.…”

Application of waste treatment sludge from water treatment in brick production

“…Higher percentages of sludge in brick caused less bonding to occur and decrease in compressive strength. These were due to the decrease of the proportion of silica content in the brick mixture, which increased the open pores between the aggregates as well as the effect of discontinuous hydration process in the matrix properties (Andrade et al, 2019).…”