Structural lightweight concrete is a type of concrete made with low-density aggregate, typically with a density of 1440-1840kg/m3, in comparison to normal weight concrete which has a density of approximately 2240-2400kg/m3. The 28-day compressive strength is needed to be greater than 17MPa. These values are achieved by using lightweight coarse aggregate and normal weight fine aggregate, generally including pyro-processed shales, clays, slates, expanded slags, and expanded fly ash. (NRMCA, 2003)
The primary use and advantage of structural lightweight concrete is to decrease the weight in a concrete structure, and doing that allows there to be a reduction in the size of structural elements and the volume of concrete, and also lessens the amount of reinforcing steel that is needed. The superior strength to weight ratio that comes from these factors overcomes the fact that lightweight concrete is slightly more expensive, and still produces a more economical product. (NRMCA, 2003)
Lightweight concrete plays a major part in the construction of large-scale structures around the world, typically in bridges and high-rise buildings. With an ever-improving industry and product lightweight concrete will continue to have a vast impact in the future.
History
The use of lightweight concrete can date back to before the days of the Roman Empire, though very simple and all together fairly weak materials, they were very durable, and some existing examples can still be found in early structures of the Mediterranean era. (Expanded Shale Clay and Slate Institute, 2010) The Roman Empire then implemented the use of lightweight concrete whenever the local supply of materials would allow them, as their rapid expansion brought the need for many more strong ...
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...t only is weight an important aspect of concrete but fire resistance is a vital component of any building and therefore the concrete. The LWC fire resistant qualities are greater than that of normal concrete due to its significantly lower heat transmission. LWC can also be seen as very durable, and with a great moisture resistance even after daily cycles of wetting spanning 30years. The moisture resistance helps to prevent steel and other reinforcement components to resistance the corrosive natural of salt water. The advantages of this concrete are not only for the labourers but also helping architects and engineers open up a broader range of applications. Examples of new advancements due to LWC include; tall building frames, long-span roofs and bridge structures and thin shell constructions (hyperbolic parabolic roof structure, sculpture and special deign effects).
Yegul, Fikret . "ROMAN CONCRETE." Roman Building Technology and Architecture. University of California, n.d. Web. 23 Nov. 2014.
At first the Romans did not realize the superior ability of concrete. They began by using it as a fill. They would also cover up the concrete with decorated stones. The concrete they used did not look pleasing because they had mixed it with any arrogate they had available. Later, once they discovered how useful concrete could be, they used it for everything they could. They built their houses, roads government offices, theaters, temples, and everything else they could out of concrete. Concrete was far superior in strength to stone and mortar, and it was easier to make than marble was to quarry and assemble.
If the ancient Roman innovation of concrete, were to not have been significant, it would not have continued to be used across the globe. In fact, ancient Roman hydraulic cement-based concrete was so notable that modern day scientists are trying to, “replicate the exact formula for which ancient Roman concrete was made.” This is due to ancient Roman concrete being so sturdy and strong that aspects of it have lasted over 2000 years without deterioration. Without the innovation of Roman concrete, many of the modern world’s infrastructure would not be stable, causing havoc across the globe. Also, advancements in construction, health, and even safety areas would not be possible, as almost every piece of infrastructure, from sewerage and water pipes, to building and security walls, would not be able to remain as safe to use. This is because the modern world relies so heavily on concrete, with around five billion tonnes of concrete being used around the world each year,becoming the single most widely used material in the construction industry. In fact, around 76% of all first-world infrastructure is reinforced with concrete. Without this substance, much of the modern-world's infrastructure would not be as tall or sturdy as what it currently is, as it would simply deteriorate or break. Hydraulic cement-based concrete is certainly the most significant Roman
The Pantheon was a Roman concrete structure. Roman concrete is a mixture of lime and volcanic ash (pozzolana, found near modern-day town Pozzouli). Roman concrete is also called hydraulic cement-based concrete. It is known for curing relatively rapidly, even in damp condition, thus it could be used for massive construction. The most daring thing about the use of Roman concrete in the Pantheon is that Portland cement needs steel reinforcement due to tendency of cracking caused by tension forces, meanwhile the Pantheon did not. The Pantheon still stands today is because of its special structure.
The Romans discovered many things that would aid the construction of their great civilization. The Romans discovered that a particular mixture of volcanic rock rubble and water could be used to create very strong structures; their concrete mixture could even be used in underwater applications. The Romans used concrete to make foundations for large buildings as well as bridges. They also used concrete as mortar to hold together the stones that made up roads, walls, and bridges. The Romans discovery of concrete allowed them to build very large structures that have survived many centuries.
One of a important achievement was the invention of concrete. They built numerous concrete structures, including the Pantheon in Rome, one of the finest examples of Roman architecture that survives to this day, which has a 42-meter-diameter dome made of poured concrete. The name concrete comes from the Latin "concretus", which means to grow together. This is a good name for this material, as the chemical hydration process, which mainly occurs over the time scale of hours and days, causes the material to grow together from a viscoelastic, moldable liquid
Concrete is one of the world’s most popular construction materials. Some six billion tonnes of concrete is produced each year in the world, making it approximately one ton of concrete for every human being per year (Fardis, 2012, p.116). However, the lifecycle of concrete does not make it the most sustainable building material at the moment. Because of limited natural resources, concerns over green house gases, and landfill problems, concrete production is being cut-back, or at least cannot be increased to keep up with population increase. In this essay, I will look at what makes concrete an unsustainable material and possible solutions to make concrete a more sustainable material.
The Romans basically invented concrete, which came to be known as Roman concrete (opus caementicium). The interesting part that made Roman concrete so durable and long-lasting was that they used volcanic Italian sand, “also known as pozzolana.” (Khan, 2017) The other part that made this such a fine building material was that it could be set underwater, practically unheard of for that time. In addition, when this pozzolana was combined with other pieces such as stones and bricks, it allowed large and very strong structures to be built.
Now a days HPC is expensive than conventional concrete. It require additional materials in some quantities as to meet specified performance.These additional materials are cement,silica fume,...
Concrete is one of the most widely used construction material in the world. The reason for this is because concrete is strong, easy to make and can be molded into various shapes and sizes. Besides that, concrete is cheap, affordable and is readily mix.
Through investigating the various properties of Cement/Concrete/Mortar, Glass, and Ceramics/Porcelain I have come to understand the chemical composition, type of bond, structure, and the daily use of each of the substances. Cement is composed of calcium which usually is acquired from limestone and silicon which is usually from sand, shale or clay (aluminosilicates). The structure of cement is in between the two extremes of an ionic and a covalent model. It is between an ionic oxide lattice and a tetrahedral covalent network. Cement when wet or when dry has both cohesive and adhesive properties. Concrete is created through the mixture of cement (filler), fine and coarse aggregate (binder), and water. With the characteristics of these materials, concrete’s type of bond attributes to its high thermal insulation properties and the strength of the material itself. Concrete is used for building materials and due to its thermal insulation properties as insulators. Mortar is a mixture of cementitious materials, water, and aggregate. For commercial use in buildings and constructions, it is useful by having water retentivity and its strength after stiffening and hardening. In addition, the content in the mortar of cement as well as air content affects the strength of the tensile bond between the mortar and the masonry. Due to the materials that compose mortar, it developed a chemical structure that is similar to its components. Also, in daily use, mortar is used for construction for buildings to attach segments together.
Concrete construction operations are of vital importance for the designer of the structure. The safety of any structure is related to the certain design criteria which
Opus caementicium or Roman concrete is a synthetic construction substance that’s composed of an aggregate, a binding agent, and water. In Rome’s case, as discovered by UC Berkley with the extensive analysis of a sample of Roman concrete taken from a breakwater in Italy’s Pozzuoli Bay it was developed by using lime and volcanic rock which formed a mortar, the mortar and volcanic rock were then packed into wooden forms and when seawater was added a chemical reaction occurred, bonding everything together to create concrete (History, 2013). It is uncertain when Roman concrete was developed, but it was clearly in widespread and customary use from about 150 BC; some scholars believe it was developed a century before that.
The usage of concrete was explored by the Early Christian and Roman architects but fell out of use throughout the Middle Ages and Renaissance period. The material was only fully explored again in the later half of the 19th century but only for mundane purposes where the material was cheap, easy to work with, and versatile, but most importantly it’s fireproof characteristic. In 1870, the idea of reinforcing the concrete was born; steel rods were to be inserted to increase its strength. Taking this principle, Ernest Ransome (America) and Francois Hennebique (France) both developed frame systems. From this, open plan workspaces with large windows were created and it was proved to be well accommodated where fire had previously been a danger. Hennebique’s system used slim vertical posts, thin parallel beams on brackets and floor slabs; this resulted somewhat like a timber frame. Concrete was one of the most flexible materials and one with a least determining form. Concrete relied on its mould and the intelligence of its designer to give it aesthetic qualities for one to appreciate it. This became much more obvious when the architects of the last 19th century attempted to discover a style based on this material.
Sustainable concrete materials and sustainable steel reinforcement have been introduced to civil engineers to get closer to the sustainable development. Sustainable buildings constructed with use of these materials have shown an increased service life and the final cost has been reduced due to them.