Behavior of Cementitious Materials under the Effect of an Eco-Cement Based on Dredged Sludge

This paper attempts to simulate the use of green materials from the silt in a dam, and reduce the harmful impacts of siltation on Algerian dams affected by frequent droughts and irregular rainfalls, which are resulted from climate change. These harsh weather conditions are the main cause of water erosion in Algeria, leading to a high silting level in many dams across the country. Therefore, it is necessary to dredge the considerable volumes of sludge in the dam areas. This paper treats the sludge dredged from the K’sob dam, and adds the treated sludge into cement, creating a hybrid binder that can be used in composition of cementitious materials. Specifically, the sludge extracted from the K’sob dam was characterized chemically, physically, mineralogically, and mechanically, and introduced both as a substitute of cement and a component in the mixture of ordinary concrete/mortar. The sludge was firstly activated through calcination, and added to cement at the mass dosages of 10%, 15%, and 20% separately. The mechanical behavior, especially that under compression, of cementitious materials (concrete/mortar) based on the treated sludge was studied through lab tests. The test results show that this technical innovation gives the finished product three major properties, namely, high strength, economy, and a beneficial ecological impact. The results obtained are encouraging and promise an optimal exploitation of the sludge from similar dam areas.

Comparison of Agro-Wastes For Dewatering Enhancement For Dredged Sludge From Sewers

With the increasing wastewater generation from domestic and industrial activities due to the rapid economic development, the generation of sludge, in particular dredged sludge from municipal sewer system, has been an issue in developing countries. This study evaluated the enhancement of sewer’s sludge dewatering via mixing the sludge with different agro-wastes, including corn core powder, rice husk powder, bagasse powder and peanut shell powder. The addition of these agro-waste powders helped decrease the sludge’s moisture contents up to 17% after mixing with the ratio of 1:3, 1:5 or 1:7. Statistical analysis revealed the impacts of both additive types and mixing ratio on moisture content reduction. Among the four types of agro-waste, rice husk was shown to be the best additive to dredge sludges with highest reduction of heavy metal concentration and moisture content. The addition of agro-waste powders to enhance the dewatering of sludges is quite promising in the context of promoting waste reuse and energy saving.

Valorization of Heat Treated Dredged Sludge in the Cement Matrix of Ordinary Concrete

The aim of this article is to propose a two environmental problems solution. One is the silting up of dams, despite the expensive dredging operations and the absence of a policy for the reuse of dredged sludge stored on non-agricultural land. The other represents the rate of cement used in the concrete. The dredged sludge is introduced after heating treatment at 600°C into the cement matrix of an ordinary concrete represents the proposed solution for both problems. In these eco-concretes, the cement has been replaced by treated dredged sludge at different percentages (5-10-20%) with a similar amount of water. Physical measurements and mechanical tests like shrinkage, absorption, and ultrasonic pulse velocity indicated dependence on substitution under dilution effect. Thermogravimetric analysis like the produced portlandite rate indicates a lack of reactive silica to supply the pozzolanic reaction. The results reveal that the substitution of 5% of cement by treated sludge leads to an appropriate concrete and minimizes the siltation effect.