Mechanical Properties of Self-Compacted Concrete

In this research, trial mixes were conducted according to Self-Compacted Concrete (SCC) specifications, a mix that gave a higher compressive strength to the age of seven days has been selected. Then after selecting the appropriate mix, concrete samples had poured and were distributed into five groups; each group consists of six cubes, six cylinders, and six prisms. The samples of each group are testing for compressive, tensile splitting, and flexure strengths respectively for the ages of 7, 14, 28, 60, and 90 days respectively. Before of conduction of destructive tests, the samples were tested using ultrasonic waves to determine the relationship between the concrete strength and pulse velocity and in the same way for all ages in above. Experimental results showed that, all concrete mechanical properties have improved, and the maximum improve was in flexural strength followed by compressive strength and tensile splitting strength. The cube compressive strength increased according to (G1 at 7 days curing) from 34.3% to 71.8%, the percentage of increase of tensile strength according to (G1 at 7 days curing) from 16.8% to 64.3% , modulus of rupture increased according to (G1 at 7 days curing) from 34.6% to 98.7% for ages (14, 28, 60, 90 days) respectively. Pulls velocity increased according to (G1 at 7 days curing): For cube from 5.1% to 23.9%, for cylinder from 21.4% to 40.3%, for prisms from 7.1% to 29.2%

Properties of Green Concrete Mixes Containing Metakaolin, Micro Silica, Steel Slag, and Recycled Mosaic Tiles

Recently, the constructions industry begins to make concrete more sustainable, side by side, with making its high performance. This paper aims to investigate the effect of (Metakaolin and Micro Silica) when they replace cement by (8, 12 and 16) % and (6, 9 and 12) % respectively, recycled steel slag when replaces fine aggregate by (10, 20 and 30) %, and recycled mosaic tiles when replaces coarse aggregate by (33.33, 66.67 and 100) % each one another on the slump, density, absorption and compressive strength of concrete. The experimental results showed that the maximum reduction ratio of cement reach (17%) (8% of metakaolin and 9% Micro Silica) while the optimum percentage of mosaic tiles and steel slag is (100%) and (20%) respectively. The optimum percentages obtained are combining to produce three basic green mixes: 1) 17% (8% of Metakaolin and 9% of Micro Silica) only, (2) A mix containing 17% of (Metakaolin and of Micro Silica) plus 100% of recycled mosaic, (3) 17% of (Metakaolin and Micro Silica), 100% of recycled mosaic and 20% of slag. Compressive strength at (7, 28, and 60) days, modulus of rupture at (28) days, absorption, fresh and hardened density are investigated. The best improvement in compressive strength compared with reference concrete was recorded (20.06, 10.855 and 9.983) % at (7, 28 and 60) days respectively for the mix containing (17% of cementitious materials plus 100% of recycled mosaic) while the ultimate flexure strength (24) % appeared in green mix containing (17% of cementitious materials, 100% of recycled mosaic and 20% of slag). Generally, an inverse relationship between density and absorption in all trail mixes which are conducted

Structural Behavior Of Simple Supported Two Layers Reinforced Concrete (Normal strength concrete & Mortar with 3-Dimension glass fiber), Beams

This paper represents an experimental investigation of the layered concrete beam. It contains studying the possibility of using the mortar intervention with layers of glass fibre at the tension zone in a loaded supported concrete beam. To produce a beam with less weight than the beam with all Normal concrete and detecting the effect of this replacement on beam properties. A rectangular beams section (150*200*1000)mm cast with NSC (normal strength concrete) at compression zone and mortar with layers of 3D glass fibre used as a part of the tension zone. The produced beams are layered beams with a lighter weight than the homogenous RC beam. Three deferent levels of the replaced layers (1/3,1/2, and 2/3 of the beam thickness) were studied, all beams were tested under Two point load till failure. The maximum load capacity result shows an apparent lowering in the load capacity of the beam, but as the lightweight layer increases, this lowering in the load capacity becomes less. for (1/3,1/2 and 2/3) of the beam thickness replace with mortar and 3D textile fibre, the lowering percentage of failure load compare with the homogenous reinforced concrete beam are (33.04%, 27.18%, and 19.73%), and the lowering in weight is (5.45%%, 9.07%, and 12..92%) for the same sequence, respectively. Stiffness, ductility and toughness of all beams are tested. An apparent lowering in the stiffness value of the layered beams is recorded with the reference ones. At the same time, it shows an increase in the toughness and toughness value