New Technology in RMC - Structural Lightweight Concrete

One of the most defining aspects of modern society is our ability to create the things we require, be it food, shelter, or clothing, and being an integral part of construction, concrete is arguably one of the most essential parts of development today. In fact, India is currently the second largest producer of cement in the world, one of the chief ingredients of concrete. Initiatives like the development of 98 smart cities in the country, along with the dependence of several industries on concrete, including housing and real estate, has provided a huge boost to the sector. This, in turn, has opened up avenues for the development and use of several different types of specialized concrete, such as Structural Lightweight Concrete, one of the latest technologies in the Ready-Mix-Concrete (RMC) and construction industry.

The primary reason for the rising popularity of Structural Lightweight Concrete over regular concrete in the construction sector is the fact that it has strengths comparable to regular concrete, and yet, is typically 25 percent to 50 percent lighter, like aluminium to steel in automotive industry. It has a density ranging from 1000 - 1800 kg/m3 and strength ranging from 10 - 40 mpa. The American Concrete Institute (ACI) states that structural lightweight aggregate concretes possess a 28-day compressive strength of roughly 17 mpa and above, while weighing not more than 1850 kg/m3. Structural Lightweight Concrete is made with processed aggregates such as expanded or sintered clays, shale, slates, fly ash, and slag or with naturally occurring light weight rocks like pumice and scoria.

The low concrete density is achieved by using low-density aggregates and a specific concrete mix design, which helps it offer significantly higher building design flexibility than regular concrete, along with increased over all cost savings. The main advantages of Structural Light Weight Concrete Structure can be noted as follows:

• Lower Dead Load  
• Improved Seismic Structural Response 
• Longer Span 
• Improved Fire Ratings and Fire Endurance 
• Improved Thermal & Acoustic Resistance 

As a result, Structural Lightweight Concrete can be used extensively in top floors of high rise construction, long span bridges, steel structures, marine structures, screeds among others. In fact, owing to its low density, durability, longevity, and freeze and thaw resistance, it was even used in the construction of ships during World War-I and II. This was because lightweight reinforced concrete ships had a considerably longer life expectancy and lower maintenance costs, compared to ones made using steel.

The 50 percent load reduction of Structural Light Weight Concrete from Normal Concrete came as blessing to one of our clients in Surat, where Nuvoco developed and supplied 1,200 kg/m3 Density M15 Grade Stuctural Light Weight Concrete for the construction of precast structural elements for toilet blocks which needs to be shifted to Mumbai 300 km away by road. The specialized engineered product offered easy handling on table tilting type precast formwork, coupled with high early strength for early deshuttering helped improved factory output by 30 percent. The self-curing property also helped lower water requirement for the curing process. The overall reduction in precast element weight considerably reduced trucking and placement costs as well.