Construction Materials, Vol. 6, Pages 81: An Innovative Way of Using Quarry Sludge and Fly Ash as a Sustainable Approach for Compressed Earth Blocks

Construction Materials, Vol. 6, Pages 81: An Innovative Way of Using Quarry Sludge and Fly Ash as a Sustainable Approach for Compressed Earth Blocks

Construction Materials doi: 10.3390/constrmater6050081

Authors:
Jose Zelaya
Nicolás Pardo
Yhan Arias

Quarry sludge (QS), a residue generated by the washing operations during the manufacture of aggregate materials used for mortar and concrete, is considered a local environmental threat for air, water, and different ecosystems. This study aimed to assess the feasibility of using the alkali activation of fly ash (FA) with a potassium hydroxide solution to stabilize the residue as an environmentally friendly solution to elaborate compressed earth blocks (CEBs). QS–FA systems were characterized by using Proctor compaction, unconfined compressive strength (UCS), scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffraction, and a computational analysis model. The results showed that this approach is an alternative for the elaboration of CEBs with estimated strength levels potentially compatible with Type 5 classification (up to 8 MPa compressive strength). While increasing the fly ash content, the K2O/Al2O3 molar ratio achieved values between 0.5 and 1.5, developing the best UCS with 40 °C curing temperature due to the formation of a K-Al-Si-rich reaction product (K-A-S-H-type).