Sewage sludge. Source: wikipedia.orgSewage water treatment produces a considerable amount of sludge, which is a challenge for wastewater plants. In Malaysia, the volume of sludge is expected to rise, yet disposal options are limited as stricter environmental regulations include a ban on burying sludge in soil due to its high heavy metal content. At the same time, the construction industry is studying alternative economically and ecologically sound cement replacement materials as concrete demand continues to rise.

The Pertanika Journal of Science and Technology published a recent study by researchers from Universiti Teknologi MARA who investigated the potential of sludge as an alternative cement material for making concrete. Using different proportions of domestic waste sludge powder (DWSP), the researchers mixed it with cement to produce varieties of concrete (normal strength Grade 30 and higher strength Grades 40 and 50). They then compared each concrete mixture with normal concrete in terms of their compressive strength, water absorption, water permeability and rapid chloride ion penetration (that is, permeability to salt).

The study found that the compressive strengths of DWSP concrete decreased as the proportion of DWSP increased in concrete mix, with the exception of Grade 40 concrete containing 7% DWSP. Both water absorption and water permeability increased as the percentage of DWSP increased.

However, normal concrete was more permeable than DWSP concrete of Grade 40, suggesting that DWSP enhanced concrete durability. Additionally, the resistance to chloride permeability increased for concretes with up to 15% DWSP.

Relevant links:

Pertanika Journals

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