Gönen, Tahir; Cemalgil, Selim

Concrete quality is affected by many factors such as mixing ratios, material quality, transporting, placing and curing. One of the crucial factors that changes the compressive strength of concrete is aggregate which makes up 75% of concrete during concrete production. Properties of aggregate are more unstable than other materials depending on various reasons. Granulometry, moisture or organic substance amount of the aggregates which have same origin may differ within time. This study investigates physical and mechanical properties of crushed limestone and crushed river aggregates. It is on optimum design of concrete with crushed limestone and crushed river aggregates. At first, physical and mechanical properties of the aggregates are measured, then Taguchi method is applied. Test variables are water-to-binder ratio, cement dosage, river sand ratio to limestone and air entrained agent. L16 orthogonal array as an experimental design method is applied to determine the optimum concrete design in terms of compressive strength and flexural strength. Furthermore, contribution of variables on compressive and flexure strength is determined statically by using ANOVA method. Among the 4 different aggregate ratios evaluated in the study, the best performance is from the combination of 70% stream and 30% limestone. The weakest performance is from the series that do not contain any stream material.

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Gönen, Tahir; Yazicioglu, Salih

Lightweight concrete has important advantages, especially in terms of earthquakes. Besides, the production of lightweight concrete with lightweight aggregate is a problem, because workability of lightweight concrete is difficult. If self compaction property can be added to the lightweight concrete, this negativity can be removed. In this study, mechanical properties of self compacting lightweight concrete (SCLWC) containing expanded perlite and pumice aggregates were investigated. Moreover, mechanical properties of self compacting (SCC) and lightweight (LC) concrete were investigated by being compared with SCLWC. Powder phase of self compacting lightweight concrete was consisted of CEM I 42.5 N cement type and C class fly ash. Pumice and expanded perlite aggregates were used in aggregate phase. Compressive strength and flexural tensile strength at 7, 28 and 90 days were determined on specimens were cured in water and air at the same ages. Obtained test results showed that SCLWC of 50 MPa compressive strength at 28 days can be produced by the use of lightweight aggregate and this concrete was not effect to curing condition as much as conventional concrete.

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