Potential use of UK sewage sludge ash in cement-based concrete

Abstract

Sewage sludge ash (SSA) arises as a by-product of the treatment of wastewater by combustion and has been identified for potential use in various construction products, such as brick manufacture, artificial aggregate and cement replacement in concrete. This paper reports on research that looked at replacing the cement or fine aggregate fraction in concretes with SSA from three UK wastewater plants. The first phase of the study established whether the physical and chemical properties of SSA were suitable for use in concrete. The potential reactivity of the material, when used as a cement replacement, was assessed for mortar specimens. In the second phase, SSA was used as a cement replacement in structural grade concrete and as a fine aggregate in foamed concrete. The overall findings of the study were that although the chemical properties of SSA indicated that it had limited reactive abilities, the porous and friable nature of SSA was such that it masked any strength development in conventional concrete and may require further processing to be used effectively. However, this characteristic was a benefit when used as a fine aggregate in foamed concrete, as it enhanced the thermal properties of the concrete by more than a third.

Hydration mechanisms of sewage sludge ashes used as cement replacement

“…Fig. 2 illustrates the variation range and average weight percentage of the major components of SSAs, compiled from former studies [2,3,[7][8][9]15,19,21,30,31,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]. Given the wide range of variation of the oxides (e.g.…”

Sustainable transformation of sewage sludge ash and waste industrial additive into green cement blend

“…The XRD result in Figure 9a,b shows that the dominant crystalline components of the SSA and CLS. They included quartz (SiO 2 ), margerite (CaAl 2 (Si 2 Al 2 )O 10 (OH 2 )), tridymite(SiO 2 ), whitlockite (Ca , Mg) 3 (PO 4 ) 2 ), albite (NaAlSi 3 O 8 ), hematite (Fe 2 O 3 ), and cristobalite (SiO 2 ) 35,37–39 . The quantity of other material (amorphous) in the SSA and CLS in the range 43% and 60% respectively, which could indicate that it has pozzolanic properties.…”

Use of Sewage Sludge Ash in the Production of Innovative Bricks—An Example of a Circular Economy

“…Worldwide, mainly in the USA, the EU, and Japan, about 1.7 million tons of incinerated sewage-sludge ash (SSA) are generated [18,19]. SSA is mostly disposed of in controlled landfills, although there are numerous examples of positive practices in the use of SSA in construction [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. It is obvious that the developed countries in the world are positively oriented to a circular economy and looking for technologies to make use of SS through its complete digestion by thermal treatment (with maximum energy recovery) and with the use of SSA (agricultural and non-agricultural land, construction, etc.).…”