INTRODUCTION
The development of sustainable construction materials has led to growing interest in the use of autoclaved aerated concrete (AAC) incorporating industrial by-products. This research investigates the effects of autoclaving parameters on AAC made from recycled concrete powder (RCP), calcium carbide slag (CCS), fly ash (FA), and phosphogypsum (PG). These materials offer environmental and economic advantages, aligning with the goals of green construction. Understanding how curing time impacts AAC’s properties is crucial to optimize its performance and durability in structural applications.
HYDRATION PRODUCT TRANSFORMATIONS
The hydration process during autoclaving plays a critical role in determining the mechanical strength of AAC. The study reveals that C-(A)-S-H phases gradually transform into tobermorite as the curing time increases. Tobermorite, especially in its fibrous form, enhances structural integrity. However, prolonged curing beyond 9 hours promotes the conversion to xonotlite, which can diminish strength, underlining the importance of precise curing time control.
PORE STRUCTURE EVOLUTION
Pore structure significantly influences the compressive strength of AAC. With increasing autoclaved curing time, the average pore size initially reduces, contributing to denser microstructure and higher strength. The formation of fine, fibrous tobermorite is key to this refinement. However, excessive curing results in coarsening of the pore network, partially reversing the gains made during earlier stages.
MICROSTRUCTURAL CHARACTERIZATION
Microstructural analysis using techniques such as SEM and XRD highlights morphological transitions in tobermorite from sheet-like to fibrous structures. These changes correlate with improvements in compressive strength and pore uniformity. Such insights are essential for tailoring AAC properties through controlled synthesis and can guide the formulation of future high-performance AAC materials.
MECHANICAL PERFORMANCE TRENDS
The compressive strength of AAC samples exhibited a significant increase with curing time up to 9 hours, peaking at 8.2 MPa. This corresponds to a 127.78% increase over the 1-hour strength value. Beyond 9 hours, the strength begins to decline due to mineralogical changes, emphasizing that an optimal autoclaving duration exists to balance hydration, densification, and crystal growth.
SUSTAINABLE MATERIALS STRATEGY
Incorporating solid waste materials like RCP, CCS, FA, and PG into AAC not only diverts waste from landfills but also contributes to the circular economy. This study demonstrates the feasibility of utilizing these materials to produce AAC with favorable mechanical properties, thereby advancing the application of low-carbon, sustainable building technologies.
Visit: civil.scifat.com
Nominate Now: https://z-i.me/civil
Hashtags:
#AutoclavedAeratedConcrete, #GreenBuildingMaterials, #SustainableConstruction, #RecycledConcretePowder, #FlyAshUtilization, #PhosphogypsumReuse, #CalciumCarbideSlag, #HydrationProducts, #Tobermorite, #Xonotlite, #MicrostructureAnalysis, #PoreStructure, #CompressiveStrength, #CuringTimeEffect, #SolidWasteRecycling, #CircularEconomy, #SEMAnalysis, #XRDCharacterization, #LowCarbonConstruction, #AdvancedConcreteMaterials