Improving recycled aggregate quality by mechanical pre-processing

• Concrete with crushed concrete aggregates (CCA) shows lesser compressive strength than reference concrete with natural aggregates. The goal of this study is to improve the strength of structural concrete with 53% and 100% CCA replacements without increasing the cement content. Thus, improvements in CCA quality are induced by combining mechanical and pre-soaking pre-processing techniques. Mechanical pre-processing by rotating drum is separately pursued on fine and coarse CCA for 10 and 15 min respectively. Results show, adhered mortar content and CCA water absorption reduces as pre-processing duration increases. Pre-processing influences CCA particle grading, flakiness index, shape index, void-content, unit-weight and density, jointly seen as packing density, which increases with pre-processing duration. Water amount to pre-soak CCA before concrete mixing is stable despite grading modifications, due to reduced water absorption resulting from mechanical pre-processing. Compressive strength and workability for pre-processed CCA50 and CCA100 concrete are comparable to reference concrete and show similar trends of improvement with packing density. Packing density markedly shows the quality improvements induced by pre-processing on CCA, maybe considered as one of the quality assessment indexes for CCA. Packing density should be investigated for other recipes to see the stability of the trend with workability and compressive strength. © 2020 by the authors. 

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering (hsv//eng)

Nyckelord

Aggregate quality

Aggregate shape

Compressive strength

Concrete recycling

Mechanical pre-processing

Packing density

Recycled aggregates

Sustainability

Workability

Aggregates

Concrete mixing

Concrete mixtures

Grading

Water absorption

Compressive strength and workability

Flakiness index

Natural aggregate

Particle grading

Quality assessment

Quality improvement

Structural concretes

Concrete aggregates

Publikations- och innehållstyp

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