Impact of the use of waste on trace element concentrations in cement and concrete

Abstract

The results of model calculations carried out to identify and quantify the input pathways of trace elements into cement and concrete and to estimate the extent to which trace element concentrations in cement may change due to waste utilization are presented. As expected, primary raw materials represented the most important input pathway for trace elements into cement, but the contribution from wastes was not negligible. The use of waste led to a slight increase of the concentrations of cadmium, antimony and zinc in cement. For cobalt, lead and vanadium, this increase was less distinct and for all other trace elements considered, the effect of the use of wastes on trace element concentrations in cement could not be demonstrated clearly. The trace element content of concrete was governed by the aggregates for most elements considered. However, for arsenic, cadmium, lead and zinc, both cement and the additive coal fly ash contributed noticeably to the total trace element concentration in the concrete.

Effect of two different sources and washing treatment on the properties of UFS by-products for mortar and concrete production

“…The leachates, alkaline throughout the testing period with pH values greater than 11, indicate that the interstitial pore fluid in contact with hydrated cementitious materials is buffered by the presence of alkaline ions. So far as the local condition of the leachant remain unchanged, the heavy metals leaching remains very low, as found in previous works [30,36]. The resistance to the leaching is the most important factor for the evaluation of the immobilised matrices, because water would be the primary liquid available for the potential dispersion for the heavy-metal ions.…”

“…Because of the use of by-products in cementitious materials may affect the trace element concentration [30], the release of heavy metals was assessed by leaching test on the specimens after 28 days of curing [31].…”

Automotive shredder residue (ASR): Reviewing its production from end-of-life vehicles (ELVs) and its recycling, energy or chemicals’ valorisation

“…Given these typical process conditions, a cement kiln seems in principle ideal for the use of waste materials as fuel. However, to guarantee that the quality standards of the clinker are met, extensive chemical analysis of the waste materials and required pre-treatments should be conducted before using a waste as an alternative fuel or resource [87,88,91].…”

Oportunidades Para Adição De Pó De Aciaria Elétrica No Cimento

“…Na produção de cimento os resíduos também podem ser utilizados como matéria-prima secundária e como aditivo na etapa de moagem, além de servirem como fonte de energia para o processo de produção do clínquer, conforme mostrado na Figura 2. Além disso, aditivos convencionais, tais como materiais pozolânicos naturais, e agregados convencionais, como brita e areia, podem ser substituídos por materiais secundários durante a produção de concreto [15].…”

“…Materiais secundários na produção de cimento (adaptado de Achternbosch [15] [22]. Ao se reutilizar a sucata galvanizada, o Zn nela contido acaba evaporando durante o processo de fusão, restando retido no PAE.…”