Ready-mix concrete

                                                               Ready-mix concrete

             Ready-mix concrete is concrete that is manufactured in a factory or batching plant, according to a set recipe, and then delivered to a work site, by truck mountedin–transit mixers. This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. The first ready-mix factory was built in the 1930s, but the industry did not begin to expand significantly until the 1980s, and it has continued to grow since then.

              Ready-mix concrete is sometimes preferred over on-site concrete mixing because of the precision of the mixture and reduced work site confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete.

Ready-mix concrete is also referred as the customized concrete products for commercial purpose. Ready-mix concrete, or RMC as it is popularly called, refers to concrete that is specifically manufactured for delivery to the customer's construction site in a freshly mixed and plastic or unhardened state. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Read-mix concrete is bought and sold by volume - usually expressed in cubic meters (cubic yards in the US).

           Ready-mix concrete is manufactured under controlled operations and transported and placed at site using sophisticated equipment and methods. In 2011, there were 2,223 companies employing 72,924 workers that produced RMC in the United States.

TMT Bars

                                                                    TMT BARS

 Thermomechanical processing, also known as thermo-mechanical treatment (TMT), is a metallurgical process that integrates work hardening and heat-treatment into a single process.^[1] A description of its application in rebar steel follows.

The quenching process produces a high strength bar from inexpensive low carbon steel. The process quenches the surface layer of the bar, which pressurizes and deforms the crystal structure of intermediate layers, and simultaneously begins to temper the quenched layers using the heat from the bar's core.

     Steel billets 125mm² ("pencil ingots") are heated to approximately 1100°C in a reheat furnace. Then, they are progressively rolled to reduce the billets to the final size and shape of reinforcing bar. After the last rolling stand, the billet moves through a quench box. The quenching converts the billet's surface layer to martensite, and causes it to shrink. The shrinkage pressurizes the core, helping to form the correct crystal structures. The core remains hot, and austenitic. A microprocessor controls the water flow to the quench box, to manage the temperature difference through the cross-section of the bars. The correct temperature difference assures that all processes occur, and bars have the necessary mechanical properties.

      The bar leaves the quench box with a temperature gradient through its cross section. As the bar cools, heat flows from the bar's centre to its surface so that the bar's heat and pressure correctly tempers an intermediate ring of martensite andbainite.

Finally, the slow cooling after quenching automatically tempers the austenitic core to ferrite and pearlite on the cooling bed.

     These bars therefore exhibit a variation in microstructure in their cross section, having strong, tough, tempered martensite in the surface layer of the bar, an intermediate layer of martensite and bainite, and a refined, tough and ductile ferrite and pearlite core.

When the cut ends of TMT bars are etched in Nital (a mixture of nitric acid and methanol), three distinct rings appear: 1. A tempered outer ring of martensite, 2. A semi-tempered middle ring of martensite and bainite, and 3. a mild circular core of bainite, ferrite and pearlite. This is the desired micro structure for quality construction rebar.

     In contrast, lower grades of rebar are twisted when cold, work hardening them to increase their strength. However, after thermo mechanical treatment (TMT), bars do not need more work hardening. As there is no twisting during TMT, no torsional stress occurs, and so torsional stress cannot form surface defects in TMT bars. Therefore TMT bars resist corrosion better than cold, twisted and deformed (CTD) bars.

wall panel

                                                                        wall panel

   A wall panel is single piece of material, usually flat and cut into a rectangular shape, that serves as the visible and exposed covering for a wall. Wall panels are functional as well as decorative, providing insulation and soundproofing, combined with uniformity of appearance, along with some measure of durability or ease of replaceability. While there is no set size limit for a piece of material fulfilling these functions, the maximum practical size for wall panels has been suggested to be 24 feet by 8 feet, to allow for transportation.

       Use of wall panels can reduce construction costs by providing a consistent appearance to the panelled surface without requiring the application of paint or another finishing material. Wall panels may be finished on only one side, if the other side is going to be against a brick or concrete wall, or a comparable structure. Alternately, the panels may, if assembled to an appropriate framework, substitute for having any other kind of wall at all. Holes may be cut or drilled into a wall panel to accommodate electrical outlets and other devices coming out of the wall.

       There is a new type of eco friendly 3d wall panel made out of the fibrous residue of sugarcane. This fibres of crushed sugarcane stalks, remaining after raw sugar is extracted from the juice of the sugarcane by shredding it, is now the raw material, called bagasse, that forms the base of this easily installed eco friendly product. The raw material used for these 3d wall panel is 100% recycled, compostable and is therefore 100% biodegradable.