Concrete layers are a major element of construction, allowing for structural strength to be achieved. They are made up of various layers that work together in a manner similar to a chain, with the bond strength of successive layers contributing to the overall strength of the building.
Shear strength of concrete layers
The shear strength of concrete layers depends on a number of factors. One of the most important is the percentage of steel fibres in the beams. Increasing the % of steel fibres improves the strength of the concrete. In addition, the addition of carbonation increases the shear strength by 30%. However, it also decreases the workability of the concrete.
There are several other methods for assessing the shear strength of concrete layers. One such method is the pull out test. This is used to calculate the shear bond strength. Another technique is the laser roughness analyzer. This machine is designed to characterize the roughness of the substrate surface.
In the literature review, there are three different models to consider: a finite element model, the Yang critically shear displacement theory, and the Muttoni critical shear crack theory. These three models are compared to build a numerical model for a composite concrete slab specimen.
According to the literature review, the shear strength of concrete is a function of many variables. For example, the shear capacity of the slab depends on its width-depth ratio, as well as the quality of its aggregates.
Bond strength ratio between successive layers
If you have read the literature, you may have come across the term “bond strength” and know it refers to the degree of interfacial resistance of a material. In this study, bond strength between successive layers of SCC mix was measured using cubic samples. The results provided valuable observations and suggestions for further investigations.
Bond strength between two layers of SCC mix is generated by the proper mixing of the layers. The bond strength is also affected by the length of time between the layers. A decrease in the bond strength between layers occurred when the time between layers increased.
The test procedure was based on standard guidelines. Cubic samples were subjected to splitting tension and then analyzed using a Computer-Aided Design (CAD) program. Using the equation for splitting tensile strength of concrete, the bond strength of the joint was calculated.
Using the same formula, the ratio of the interfacial resistance of two layers of mixture was determined. This ratio is the sum of the friction coefficient and cohesion coefficient. As the time between layers increases, the resistance of the joint increases as well.
Incompatibility of asphalt concrete pavements
Asphalt concrete is a porous material that is composed of aggregate particles, bitumen binder, and air voids. It is used as a base layer in pavements. Typically, asphalt concrete is transported by a truck to the paving site. The final asphalt mixture is compacted to a uniform thickness by a mechanical paving machine.
Various factors can negatively affect water sensitivity in the final asphalt mixture. One such factor is the use of virgin binders. This can affect rutting resistance and permanent deformations.
Another factor is the varying temperature profile. This can result in pavement failure. Specifically, oxidative degradation can occur. Aside from the aforementioned factors, there are also other potential problems. For example, aging can have severe effects on asphalt cement.
There are also some differences between the properties of the different types of asphalt concrete. These differences can have a profound impact on performance and durability.
In addition, oxidation can occur during mixing and compaction. Oxidation in asphalt can lead to a significant change in the structure of the binder. As a result, asphalt can become harder and less flexible.
Precautions when pouring concrete
When pouring concrete layers, it is important to follow certain precautions. This can help you avoid accidents and ensure your safety.
First of all, you should wear proper protective gear. Steel toed safety boots are recommended, as they protect your feet from falling objects, sharp rebar, and tie wire. Additionally, be sure to remove snow and ice from the ground before laying down the first layer.
The temperature of the ground must be warm enough for the concrete to set properly. If it is cold, it will be softer and more likely to crack.
The best way to prevent cracks is to make sure the temperature of the ground is above 50degF (10@C). Cold ground will result in the top layer of concrete being more brittle and prone to breaking.
To make sure your slab will not crack, be sure to seal it with a curing compound. Water can mix with the concrete and increase the chances of failure.