Concrete is Vital for Infrastructure

Concrete is a tough and reliable material, and it can be used for a wide range of projects. Eventually though, a structure made from this versatile material will need to be replaced. At the very least, it may require repairs.

Roman building using cement (Labate, 2016) dates from the third century BCE. Cement was used with crushed bricks and rock to produce concrete used for building. The cement was made from volcanic dust (pozzolana), lime (calcium oxide) or gypsum (calcium sulphate). This mixture reacts when mixed with water, binding the concrete into a permanent, strong, impermeable structure. The Roman engineers discovered that the use of cement in their mortar dramatically increased its strength. Special types of cement were discovered and used for under-water structures like harbors and bridge piers. Roman workmen perfected the skill of building with concrete, some of which, like the Parthenon, are still intact and beautiful to this day. During the first century CE, Rome had a “Concrete Revolution”, many concrete buildings being built as skill developed.

Proc., 7th Int. Conf. on Fracture Mechanics of Concrete and Concrete Structures. Korea Concrete Institute,

Concrete is the ultimate building block of society; there are a plethora of ways that it has been used. Romans were some of the first, in recorded history, to use it; they used it to build their aqueducts and even the Colosseum. If anything, the Romans were some of the first to make huge developments in concrete, and they were some of the first to actually use concrete on a large scale. America has also used concrete on a large scale, using concrete to build the Hoover Dam and the Grand Coulee Dam. Those examples show how concrete is an incredibly strong and durable building material that has remained standing after all these years and will continue to be the primary

One damaging effect is freezing water. When water melts, it absorbs into the pores and capillaries. As the water freezes and expands, it weakens the strength of the concrete. This causes concrete scaling, delamination, and cracking.

Fiberglass reinforced concrete (GFRC) is most suitable for construction because it is a great material for restoration of old buildings and also used for the exterior of the buildings. It is also being used widely for walls and ceilings. GFRC allow almost perfect replication of building terra-cotta and ornaments. It’s very low shrinkage allows molds to be made from existing structural ornamentation, then cast in GFRC to replicate the original designs. GFRC is lightweight compared to other traditional concrete which is very important for construction. It is highly durable and safe. Next, expensive equipment is not necessary for pouring or spraying GFRC .Fiberglass is inexpensive and corrosion-proof, but not as ductile as steel. It can only be

Reinforced conc. is available tec. for construction in Egypt and all over the world. It is used in almost all structures as: buildings, shells, bridges, tunnels, tanks and retaining walls. Conc. is made by mixing binding materials as sand and gravel held together with a paste of cement and water. Conc. has many advantages, such as high fcu, ability to cast in almost any desired shape, economical and fire resistance. Yet, there are some disadvantages, like low ft, low ductility and cracking. Regardless those disadvantages, Conc. is still one of the chosen materials in construction.

The evolution of concrete has allowed us to create more workable concrete and as a result allows better bonding due to the chemical reaction at a molecular level between the water and cement. This reaction bonds the aggregate and acts much like a “bridging” compound which binds the aggregate together.

Continuously reinforced concrete pavements (CRCP) was first designed 100 years ago when the Federal Highway Administration constructed a CRCP testing section. CRCP is now being used in numerous states around the United States and even around the world. CRCP has proven to be such a useful design. With the design and construction growing, there has been many lessons learned through its use and research. Which has contributed to better practices and a longer life cycle, making its ability to maintain a “zero-maintenance” service life through harsh environmental conditions and heavy traffic loadings. As long as proper design and construction is being utilized (as shown in figure 1) the design should need only minimal

Lightweight concrete can also be classified according to the purpose of utilizing as: i) Structural lightweight concrete has cylinder compressive strength at 28 days equal or more than 17 MPa and the approximate density range is about 1400-1800 kg/m3. ii) Masonry concrete (structural / insulating lightweight concrete) has a compressive strength between 7-14 MPa and density range 500-800 kg/m3. iii) Insulating concrete has a compressive strength between 0.7-7 kg/m3 and density lower than 800 kg/m3. (Neville and Brooks, 2010; Slaby, Aziz and Hadeed, 2008)

Introduction: It is widely known that many older reinforced concrete columns may suffer from an inadequate amount of transverse steel reinforcement providing insignificant confining pressure to the concrete core. The seismic performance of these columns may thus be very poor due to their insufficient ductility or low concrete strength. Because the FRP composites owe some of the favorable properties such as high strength-to-weight ratio, the use of FRP composites is nowadays become more common in the construction industry as a confining material for concrete to enhance the strength and ductility capacities of existing RC columns. To achieve a proper and safe design of FRP-confined rectangular RC columns, it is necessary to properly understand and model the axial stress-strain behavior of FRP-confined concrete. The axial cyclic stress-strain behavior of FRP-confined concrete is of particular importance in the seismic design of existing RC columns.

Structures and structural elements made of concrete must therefore also be able to withstand chemically attacking substances, which are constantly acting on them because this affects the concrete strength.

The objective of the hardened concrete test was to determine the compressive and indirect tensile strength. On the other hand, this experiment was also used to examine the effect of curing condition on strength of concrete, the influence of specimen shape on compressive strength, the effect of compaction on compressive strength and this experiment was also to examine the effect of increasing water to cement ratio on compressive and in direct tensile strengths of concrete.

The macroscopic material behavior of concrete is influenced by the geometry, spatial distribution and material properties of individual material constituents and their mutual interactions. Therefore, it is essential to study the influence of each material constituent in order to estimate the residual strength of the structural components. Thus, failure of concrete is a complex phenomenon due to its multiscale and multiphase nature. When the normal stress in a material reaches its tensile strength, the inhomogeneities in concrete promote the formation of an inelastic zone ahead of an existing crack termed as the fracture process zone (FPZ). The FPZ is dominated by various complicated mechanisms such as crack shielding, crack deflection, aggregate bridging and microcracking around the crack tip and exhibits a post-peak softening behavior under tensile loading. It therefore becomes necessary to include these effects for predicting reasonably well the residual strength of existing cracked and damaged structures.

Abstract 1: A slowly growing number of studies have concentrated too much on investigating, but less on modelling the cyclic axial stress-strain response of concrete columns (RC) confined with fiber-reinforced polymer FRP sheets. Since the early 1990s, the largest amount of research, including both experimental and analytical studies, has been rising continuously, in contrast, on the monotonic axial stress-strain behavior of concrete columns externally jacketed with FRP composite wraps. However, most of the available literature on the behavior of FRP-confined RC columns has focused extensively on square and circular concrete columns that can be classified as small or medium-size. Also recently, a few experimental studies have been devoted to investigating the cyclic axial compression behavior of small-scale unreinforced (plain) rectangular concrete columns with smaller-cross sections. Therefore, a deep review indicates that there is a distinct lack of research on the axial stress-strain behavior of FRP-confined RC columns subjected to a cyclic axial compression loading. This is owing to the fact that the majority of the structural buildings columns (RC) are noncircular ,and it has been clearly demonstrated that the behavior of these columns mainly depends on several factors such as aspect ratio of cross-section,