TY - JOUR
T1 - Recycling drinking water treatment sludge into eco-concrete blocks with CO2 curing
T2 - Durability and leachability
AU - Liu, Yue
AU - Zhuge, Yan
AU - Chow, Christopher W.K.
AU - Keegan, Alexandra
AU - Pham, Phuong Ngoc
AU - Li, Danda
AU - Qian, Gujie
AU - Wang, Lei
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Drinking water treatment sludge (DWTS) can be recycled into low-strength concrete blocks for construction use. The sodium sulfate resistance and leaching behaviours of the DWTS-derived blocks are investigated in this study. The experimental results show that the addition of DWTS degrades the sodium sulfate resistance of the concrete blocks, however CO2 curing compensates for such property, especially in the case of blocks incorporating 30% DWTS. The improvement can be attributed to the formation of crystalline CaCO3 during CO2 curing for microstructure refinement evidenced by X-ray Computed Tomography and Scanning Electron Microscopy. Leaching analyses show that Cu and Al concentrations increased with increasing DWTS content, and CO2 curing adversely increased the leachability of metals due to the decrease of pH, especially at early leaching stage. Nevertheless, the total leaching concentrations of Cu and Al after 60-day test is far below the prescribed limitations, regardless of samples subject to air curing or CO2 curing. In summary, sludge-derived blocks exposed to CO2 curing are safe and behave well in aggressive environments. Therefore, this study showcases a green technology that successfully recycling DWTS into value-added and durable concrete blocks with low environmental impacts.
AB - Drinking water treatment sludge (DWTS) can be recycled into low-strength concrete blocks for construction use. The sodium sulfate resistance and leaching behaviours of the DWTS-derived blocks are investigated in this study. The experimental results show that the addition of DWTS degrades the sodium sulfate resistance of the concrete blocks, however CO2 curing compensates for such property, especially in the case of blocks incorporating 30% DWTS. The improvement can be attributed to the formation of crystalline CaCO3 during CO2 curing for microstructure refinement evidenced by X-ray Computed Tomography and Scanning Electron Microscopy. Leaching analyses show that Cu and Al concentrations increased with increasing DWTS content, and CO2 curing adversely increased the leachability of metals due to the decrease of pH, especially at early leaching stage. Nevertheless, the total leaching concentrations of Cu and Al after 60-day test is far below the prescribed limitations, regardless of samples subject to air curing or CO2 curing. In summary, sludge-derived blocks exposed to CO2 curing are safe and behave well in aggressive environments. Therefore, this study showcases a green technology that successfully recycling DWTS into value-added and durable concrete blocks with low environmental impacts.
KW - Accelerated carbonation
KW - Drinking water treatment sludge
KW - Leaching behaviour
KW - Stabilisation and solidification
KW - Sulfate attack resistance
KW - Value-added recycling
UR - http://www.scopus.com/inward/record.url?scp=85088903168&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2020.141182
DO - 10.1016/j.scitotenv.2020.141182
M3 - Article
C2 - 32768782
AN - SCOPUS:85088903168
SN - 0048-9697
VL - 746
JO - Science of The Total Environment
JF - Science of The Total Environment
M1 - 141182
ER -
