HIGH PERFORMANCE CONCRETE UTILIZING RECYCLED DEMOLISHED CONCRETE

摘要

This paper reported the reliability of incorporating recycled demolished concrete (RDC) that containing either gravel or dolomite base to produce high performance concrete (HPC) with compressive strength up to 62 MPa. Thirty two mixes have been experimentally investigated and comparison technique was used to indicated the results of RDC with those of the conventional natural aggregate concrete (NAC). These mixes have been designed to achieve standard cube compressive strength ranging from 30 to 62 MPa. Two types of superplastisizer, type F (2%, 2.4% and 5%) and glenium type G (0.3%, 0.7% and 1%) have been utilized and investigated for workability and slump enhancement. Silica fume with (0-25%) was used for both RDC and NAC mixes as cement additives. Age factor till 56 days have been also considered in this research. In addition, water absorption coefficients as a durability pointer was recorded for all concrete mixes. The results of this research show that the compressive strength for RDC increases for all mixes contains type G (0.3%) without silica fume by significant ranges (7%-40%) for RDC with gravel base and (25%-53%) for RDC with dolomite base compared with NAC mixes respectively. However, for same mixes containing silica fume (10-25%), the compressive strength of RDC with gravel base is almost the same but with dolomite RDC, compressive strength increased by about (25-40%). On the other hand, incorporating type F without silica fume may lead to decrease the compressive strength for RDC with either gravel and dolomite base by 20% and 10% respectively, compared with NAC. In addition, contributed guidelines are provided on the reliability of incorporating (RDC) in achieving high performance and durable concrete are included.