Study of Use of Sewage Sludge Ash as an Addition in Concrete


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Title: Study of Use of Sewage Sludge Ash as an Addition in Concrete

Author(s): A.L.B. Geyer, D. Dal Molin, and N.C. Consoli

Publication: Special Publication

Volume: 207


Appears on pages(s): 111-124

Keywords: ash; concrete mix; incinerated sludge; sewage sludge

Date: 10/7/2002

Recently the sewage treatment in Porto Alegre, a city with a population of about 1.5 million inhabitants, located in southern Brazil, has increased. With the enlargement of the sewage treatment systems, in the year 2001 about 50% of the city sewage will be treated, which is about 100 tonnes of sludge per day. Sludge resulting from sewage treatment plants creates huge disposal problems. The government and the environmental authorities have been worried about solving this question. Nowadays there is still a lack in definitions for the final disposal and use of these residues. The main problem of this material is its components, because among them there are pathogenic organisms and heavy metals. A joint research between Municipal Prefecture of Porto Alegre and Federal University of Rio Grande do Sul was developed to study the possibility of incineration of the material and the use of the ash in construction. An experimental research program is conducted to determine the engineering properties of the incinerator solid ash. It is necessary to conduct such an investigation in order to evaluate the feasibility of using this ash as a partial substitute for cement in concrete. The initial results indicate that the waste ash may replace 20% by weight of cement in a concrete for normal use.