Durability Assessment of Recycled Concrete Aggregates for use in New Concrete: Phase I - Revised

Abstract

Type of Report and Period Covered Sponsoring Agency Code Supplementary Notes AbstractThe primary goal of this research project was to investigate the long-term durability of concrete incorporating recycled concrete aggregate (RCA) through accelerated laboratory testing. Overall it was found that modifications to standard aggregate testing and characterization standards were necessary for testing RCA. This included modifications to standard tests including ASTM C 128, C 305 and C 1260. It was found that the potential for alkalisilica reactivity did exist for new concrete containing RCA. The characteristics of the RCA also had a profound effect on ASR related expansion. RCA with a higher content of reactive coarse or fine aggregate (compared to paste fraction) exhibited greater reaction and would therefore require higher levels of mitigation. Based on testing in this research project precision and bias statements in ASTM C 1260 (for virgin aggregate) do not apply to RCA. Recommendations for future work are also included in this report.17.

Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

“…Test results from this aggregate were only used to demonstrate modifications to standard laboratory testing (e.g., specific gravity and absorption capacity testing). A summary of this work can be found in Section 3.0, with a more complete description in the Phase I report (Ideker, Tanner et al, 2012).…”

“…In short, the outdoor exposure blocks were selected for their age, extent of alkali-silica reaction damage (coming from the reactive virgin aggregates originally included in the mixture designs), and variation in mineralogy of reactive aggregate type. Data on these aggregates is presented in Section 2.1, with a more complete analysis available in the Phase I report (Ideker, Tanner et al, 2012).…”

“…Details about standard testing procedures that were not modified can be referred to in the given standard, and a more in-depth report of aggregate characterization techniques used and modifications to those techniques can be found in the Phase I report (Ideker, Tanner et al, 2012).…”

“…The results of this study will be discussed in Section 3.0. A full review of how the RCAs were crushed is available in the Phase 1 report (Ideker, Tanner et al, 2012). The RCAs used as part of the dual-laboratory study and the mitigation study (Jobe, CalPort, OPP and Steps) were used in a mixed form, incorporating both crusher's fines and re-crushed material.…”

“…The amount of expansion observed due to ASR from the RCA is dependent on the amount of RCA incorporated into the mixture, the reactivity of the original natural aggregates, and the amount of processing the RCA goes through to attain correct gradation for the requisite tests (Shehata, Christidis et al, 2010;Ideker, Tanner et al, 2012). It has also been determined that the ASTM C1260/C1567 AMBT is an effective way to detect alkali-silica reactivity (ASR) in RCA (Shehata, Christidis et al, 2010;Adams, Ideker et al, 2012).…”