Abstract
Concrete’s self-weight is a major aspect of a structure’s overall weight. Recently, the use of lightweight concrete (no-fines, foamed and cellular concrete) has been increased. Normally no-fines concrete is produced with crushed coarse aggregate of uniform gradation. This study aims to investigate experimentally the effects of the use of uncrushed coarse aggregates on unit weight, compressive and tensile strength of the no-fines (NFC) as well as conventional concrete (CC). In addition, the effects of coarse aggregate size on the mechanical properties were also studied. Four gradations of uncrushed coarse aggregates ranging between (5.5-4.75) mm, (10-4.75) mm, (20-4.75) mm and (25-4.75) mm were used for preparing the concretes. The fixed cement-aggregate ratios of 1:6 (with w/c ratio=0.4) and 1:2:4 (with w/c ratio=0.5) were adopted for NFC and CC respectively. It was found that the gradation of uncrushed coarse aggregate has a significant effect on the mechanical properties of NFC. A maximum of 16% reduction in self-weight of the concrete without fines was obtained, as compared to that with fines. Moreover, the compressive strength of no-fines concrete significantly improved by replacing crushed with uncrushed coarse aggregate. The compressive strength increased by 16% for the batch of (25-4.75) mm.
Highlights
The self-weight of concrete is a major aspect of the overall weight of the structure
In view of the aforementioned issues, this study aims at investigating the effects of uncrushed coarse aggregate on unit weight, compressive and tensile strength of the no-fines concrete (NFC)
It can be observed that the unit weight of the batch with larger size of uncrushed coarse aggregate was higher
Summary
The self-weight of concrete is a major aspect of the overall weight of the structure. In view of the aforementioned issues, this study aims at investigating the effects of uncrushed coarse aggregate on unit weight, compressive and tensile strength of the no-fines (i.e. lightweight) concrete (NFC). Compressive and tensile strength tests in specimens cast from four different batches of coarse aggregates were conducted. C. Test Methods Before the specimens of no-fine and conventional concrete were tested for compressive and split tensile strength, each specimen’s unit weight was determined. Cylinder tests were performed to determine the tensile strength of no-fines and conventional concrete In this test the concrete cylinders were placed with their horizontal axis between the platens of the UTM (Figure 3) and the load increased until failure by indirect tension in the form of splitting along vertical diameter took place. F1 2P 3.14LD where f1=tensile strength, P=ultimate applied load L=cylinder length and D= cylinder diameter
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