Enhancement of concrete properties by waste physicochemical treatment sludge of travertine processing wastewater

Travertine treatment sludges are by-products derived from travertine marble processing plants. These treatment sludges are being generated in considerable amounts in marble production plants in Turkey. Various proportions (5-15% w/w of the cement) of physicochemical sludge admixtures obtained from the physico-chemical treatment (coagulation-flocculation) of a travertine processing plant wastewater were used ascement replacement for concrete with 250 kg/m3 cement dosage. Slump tests were performed on fresh concrete, and compressive strengths were determined for 7 and 28 days hardened concrete samples. The freeze/thaw resistance, water absorption, capillary suction, void ratio and porosity were performed for the hardened concrete samples. Considering the properties of hardened concrete such as compressive strength, workability and physical properties, AS and NS are the admixtures that can be suggested both to enhance the concrete properties and to have a new utilization area for a waste material. Higher 28-day compressive strength of about 28.43 MPa (AS) and 28.82 MPa (NS) was achieved at 15% admixing level by weight of cement while reference sample compressive strength was 25 MPa.