Properties of mortar incorporating untreated and treated drinking water treatment sludge. (19th April 2021)

• Record Type: Journal Article
• Authors: Pham, Phuong Ngoc; Duan, Weiwei; Zhuge, Yan; Liu, Yue; Tormo, Ismael Esteban Serna
• Is Part Of: Construction & building materials. Volume 280(2021)
• Publication Date: 2021-04-19
• Subjects: Calcined sludge -- Sludge-modified mortars -- Bond strength -- Autogenous shrinkage -- Sludge-cement matrix interface; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.122558
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The performance of raw and treated DWTS as sand replacement in mortar was studied. Mortar samples with 5% of treated DWTS exhibit best mechanical performance. The reduction of drying shrinkage is attributed to pores refinement by treated DWTS. Treated DWTS shows a better bonding with cement matrix than the control group. Abstract: The generation of sludge originated from water treatment plants is a global problem due to the risks of the sludge to the environment. Therefore, drinking water treatment sludge has been investigated and used as a recycled construction material owing to its properties similar to clay. In this study, mortars with 0%, 5%, and 10% of sand replaced by alum-sludge were manufactured, which include a group that was treated at elevated temperature to eliminate organic content in the sludge and to activate its pozzolanic reactivity. Mechanical properties were assessed, and the mixtures incorporating treated sludge exhibited improved compressive strength compared to those untreated. A significant increase in bond strength between mortar and bricks was observed for mortar with 10% of treated sludge compared with the control group without sludge. Treatment of sludge also helped to decrease the considerable shrinkage of untreated-modified mortars. The water absorption of mortar incorporating treated sludge is also lower than that of mortar with untreated sludge due to dense microstructure, especially owing to an improved interface between treated sludge and cement matrix as demonstrated by Scanning Electron Microscope. However, sludge treatment increased the pore interconnectivity in the mortar, leading to higher water capillary absorption.