Performance of cement stabilized recycled crushed concrete

A study to advance knowledge concerning the performance and strength variability of cement stabilized recycled crushed concrete mixtures for potential use as a stabilized base or subbase material in road pavements was conducted, investigating mixtures composition. Grain size distribution tests and composition analysis were thus carried out to characterize different recycled crushed concrete mixtures. Mixture performance was evaluated in terms of unconfined compressive strength, indirect diametrical tensile strength, elastic modulus, indirect tensile resilient modulus and durability. Additionally, performance variations were examined in relation to the following items: mixtures composition, curing time, concrete ageing of original mixtures, amount of fresh cement added. Laboratory compaction of the aggregate mixed with 2% and 4% of fresh added cement was effected using gyratory compaction. Specimens were cured in a controlled climatic chamber for 7 and 28 days. The results indicate that in general, recycled concrete ageing and original characteristics significantly affect the performance of cement stabilized crushed concrete mixtures. Investigations also indicate that further detailed research is required to derive more extensive indications and also to develop a means of acceptance based on strength, suitable for use in performance based specifications. But overall, analysis of laboratory test results already indicates that given correct grading and other properties, the recycled stabilized mixtures tested can be potentially reused for pavement base and subbase layer construction.