Properties of Recycled Aggregate in Concrete and Road Pavement Applications

Rifat N Rustom, Salah Taha, Ali Badarnah, Hani Barahma

Abstract


This paper highlights the results of the performed testing program which aimed at investigating the possibility of utilizing the recycled crushed aggregates of the construction and demolition wastes (CDW) in engineering applications in Gaza Strip. The characteristics of the crushed aggregates were determined and compared to international standards. The reuse alternative is investigated in concrete mixes and road construction throughout the testing program. Eight representative samples were selected from different locations in Rafah and Khan Younis. A Technical team supervised the collection process, crushing, transporting, handling and testing program. In general, the test results showed that the recycling of the CDW aggregates and its use in both concrete and road sub-base give acceptable results. Most of the characteristic test results were within the standard limits. The results of the tests that concern road applications were good and verified the adequacy of materials. The results of the tests for concrete applications were also desirable and proved that these materials, CDW, could be used in some concrete applications. The values of the CBR ratio at 100% were 186.6 for demolition samples and 186.1 for crushed concrete samples. Comparably with the CBR of the local base course that is ranged between 100 and 130, the CBR values were high due to the large quantity of cementious materials, and achieved the minimum required value (80) for base course at 100% compaction according to AASHTO (T180-D) and (T 193). A local concrete mix design was used for testing CDW use in concrete . This mix gave a compressive strength of about 250 kg/cm2 of compressive strength at 28 days at water to cement ratio of 0.6 and 290 kg cement content. The results of the testing program of the recycled CDW were above expectations and showed, to some extent, good indications. Two testing labs were used to prepare and test the samples. Most tests at 7 and 28 days, showed high results compared to the control samples of natural materials. The results of the compressive strength of all samples at the same water to cement ratio were close to each other.

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