Details:

Creators:
Aydilek, Ahmet H.
Corporate Creators:
University of Maryland (College Park, Md.)
Subject/TRT Terms:
[+]
Aggregate Gradation California Bearing Ratio Concrete Aggregates Deformation Durability Freeze Thaw Tests Laboratory Tests Leaching Modulus Of Resilience Pavement Design Recycled Materials Stiffness
Publication/ Report Number:
MD-15-SP109B4G-2
Resource Type:
Tech Report
Geographical Coverage:
Maryland
Corporate Publisher:
Maryland. State Highway Administration. Office of Policy & Research
Abstract:
The use of recycled concrete aggregate materials in highway constructions as compared to the use of virgin

materials reduces virgin natural resource demands on the environment. In order to evaluate their potential use of

recycle materials in highway construction, two different recycled concrete aggregate (RCA) materials and two

conventional graded aggregate base (GAB) materials and the mixtures of RCA-GAB materials were tested in the

laboratory for their strength (California Bearing Ratio), resilient modulus, permanent deformation, and durability. In

addition, laboratory water leach tests (WLTs), and pH-dependent leaching tests were conducted to determine the

environmental suitability of RCA materials. The leaching behavior of Ca, Cr, Cu, Fe, and Zn from RCAs and the

effects of pH, curing time, freeze/thaw cycles, liquid-to-solid ratio, and particle size on leaching of these metals were

investigated. The summary resilient moduli (SMR) of RCAs were 2.6 and 2 times higher than that of the natural

GAB material and their stiffness increased when subjected to freezing and thawing cycles. Consistent trend could

not be observed with CBR and SMR values and percent RCA addition. Overall, GAB yielded lower permanent

deformations compared to the RCA materials. In pH-dependent leaching tests, Ca showed cationic leaching patterns,

while Cr, Cu, Zn, and Fe showed amphoteric leaching patterns. Leaching tests results indicated that leached Zn

concentrations were below the detection limits at pH>5. Increasing curing time caused rehydration of cement

particles and generally yielded a decrease in pH and leached concentrations of metals. Freezing and thawing of

RCA also led to self-cementing and decreased pH, Ca concentrations while no consistent trends were found between

the leaching of Cr, Cu, and Fe concentration and freeze-thaw cycles. Increasing the liquid-to-solid ratio decreased

leaching of elements significantly due to the dilution of leached elements in the aqueous solutions.


Format:
PDF
Funding:
SP109B4G
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:07cd91baab80e5b17fc8c1e3a8a633a8741d8c40af0fee095f9c8e8b5500c647
Download URL:
https://rosap.ntl.bts.gov/view/dot/28447/dot_28447_DS1.pdf
File Type:

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