Some properties of no-fines concrete produced by using demolished concrete as recycled coarse aggregate

Abstract EN

This paper investigate some mechanical properties of no-fines concrete produced by using demolished concrete as coarse aggregate after crushing to different sizes.

Different no-fine mixes were considered using Portland cement type I with two types of coarse aggregates, crushed natural gravel and crushed demolished concrete were used with two ratios by weight (1:5 and 1:7) cement/aggregate.

Single size and graded aggregate were used with a maximum size of 20 mm.

W /C ratio was kept as 0.4 for all mixes and supper plasticizer was used to keep the same flow and compaction factor value for all mixes .

Using demolished concrete as coarse aggregate in no fine concrete led to decrease in the workability.

As a comparison with natural coarse aggregate mixes, the average percentages of decreases for the flow, compaction factor and the fresh density were 2%, 2.3% and 6.4%, respectively.

As well as the test results indicated that the compressive strength, splitting tensile strength, flexural strength and oven dry density for no fine made with crushed demolished concrete at age 28 days were decreased by about 29%, 22 %, 21% and 4% respectively as compared with no fine made by natural crushed aggregate.