Compressive Properties, Concrete

Table 1 shows the three mix designs the six different tests performed to the plastic modified concrete. Axial compression on concrete cylinders was tested in two different mix designs, No. 1 and No. 2. The other properties were examined only for one of the mix designs. 

The sound speed c, m s , is the velocity of propagation of the pressure variations. This depends on the physical properties of the medium and increases with the density of the medium. In air, for example, it is. 344 m s, while in water, 1410 m s and in concrete, 3000 m s . The elapsed time between successive compressions is called the period time T. 

Structural steel has the advantage of quick assembly at the jobsite. Specialized elements, such as doors, are usually delivered in one piece ready for installation into concrete formwork or into the building frame. Being a factory produced material, steel has well controlled and predictable strength and post-yield properties. Unlike concrete, steel has good tensile as well as compressive strength. 

The major physical attributes of concrete as a construction material are a high compressive strength and stiffness, an ability to protect and restrain steel and, most important of all, to retain these properties over a considerable period of time. The effects that water-reducing admixtures have on these properties can be considered from the point of view of design parameters, i.e. those properties of concrete at a relatively early age (usually 28 days) which are used for structural calculations, and longer-term aspects or durability. 

The three most important properties of concrete used in calculations for load-bearing applications are the compressive strength, the tensile strength and the modulus. However, for certain applications, e.g. water-retaining structures, the permeability or porosity of the concrete will be a relevant design criterion and this is also considered here. 

Physical properties of CSA-contaming concretes (compressive strength, creep, modulus of elasticity and durability) are comparable to those of corresponding Portland cement concretes, especially when CSA is used at dosages of 8-11%. When the dosage exceeds the ranges mentioned above and no restraint is provided either internally (by reinforcement) or... 

Properties of hardened concrete Average compressive strength ... 

When concrete is specified by compressive strength and workability, normalsetting and retarding water-reducing admixtures (both normal and mid-range types) are widely used as a means of attaining the required properties at lower cement contents than mixes which contain no admixture. Although the use of admixtures... 

In examining the strength properties of sulfur concrete modified with styrene, the compressive strength was insufficient and worse than in the case of unmodified sulfur concrete (Table VI). After 70 days storage, however, the compressive strength of the test samples modified with 10 wt % styrene increased to 432 kp/cm2, which is an average of 46%. The increase in the test samples modified with 5 wt % styrene was 4%, corresponding to a value of 526 kp/cm2. 

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