Reusing thermoactivated construction waste spoil as sustainable binder for durable concrete: Microstructure and chloride transport

Construction and demolition waste is predominantly comprised of construction spoil. However, the proper recycling of this construction spoil in a manner that maximizes its value has historically received insufficient attention. Therefore, the objective of this study investigated the micro-structure and chloride transport of cement concrete including thermoactivated construction spoil powder (CSP) as a substitute for cement. The results highlights that the un-treated CSP consisted of massive inert components, and active metakaolin and amorphous components were generated in thermoactivated CSP after 800-1200 & DEG;C activation treatment. Mixing un-treated CSP negatively impacted the micro-structure and strength development of concrete, but the thermoactivated CSP blended paste had improved micro-structure and better strength than the un-treated CSP blended paste. Incor-porating un-treated CSP raised the chloride transport in concrete. At the constant replacement ratio of CSP, the thermoactivated CSP blended concrete had lower chloride transport than the un-treated CSP blended concrete, and decreasing the particle size of thermoactivated CSP could further decline the chloride transport in ther-moactivated CSP blended concrete. The concrete with 1200 & DEG;C-activated CSP even had lower chloride transport than the reference concrete. The mix of un-treated CSP up to 30% reduced the chloride binding capacity of concrete, but the thermoactivated CSP blended concrete had superior chloride binding capacity to the un-treated CSP blended concrete. Particularly, the concrete with 20% thermoactivated CSP and 10% active metakaolin/ silica fume had similar strength and lower chloride transport than reference concrete. By optimizing the ther-moactivation temperature, replacement ratio, and particle size of CSP, it was possible to prepare a durable concrete with low chloride transport.

Automated summary

The objective of this study was to investigate the micro-structure and chloride transport of cement concrete using thermoactivated construction spoil powder (CSP) as a substitute for cement. The results highlighted that the thermoactivated CSP improved the micro-structure and strength of the concrete, while un-treated CSP had a negative impact.