Bangladesh has seen tremendous growth in terms of infrastructure development in the last decade. The country’s aspiration for sustained economic growth and to become a middle-income country leads the decision-makers to implement infrastructure-related mega projects. Due to the nature of the soil, geographical position, and the many rivers flowing through the country, adaptation of modern technologies is required to make the projects sustainable, economically viable, and environmentally friendly.
Especially for projects like Hydraulic Protection, Environmental Sustainability, Geohazard Risk Mitigation, Precast Crossing Structures, Retaining Structures, Soil Reinforcement, and Ground Stabilization, innovative technologies blended with the right set of engineering solutions must be placed to direct the projects in the right direction.
Here, we will review some technologies that enable us to navigate the challenges of infrastructural development.
Hydraulic protection
Hydraulic protection, more commonly known as river/shore protection, can be a classic example of adopting new technologies to make it sustainable, economically viable, and eco-friendly at the same time. In Bangladesh, earthen embankments, concrete blocks, and sand filled with geo-bag solutions are conventional methods that are widely used. The disadvantages associated with these problems are erosion if exposed to waves, sustainability, quality assurance, slow project execution, and continuous maintenance. A French technology, articulated block concrete mattress, commercially known as ‘TechRevetment’, addresses these challenges. It offers solutions already used across Europe, Asia Pacific, and other parts of the world.
TechRevetment is a pre-engineered factory custom-grouted mattress system for permanent erosion protection works. This technology is used to protect embankments (dry or wet), bridge abutments against scour, waterways, and canal lining, as well as mining and industrial erosion protection and lining applications. This system can be installed underwater without dewatering, and installation is faster.
TechRevetment is an alternative and durable solution for erosion. It is flexible and can adapt to the soil contour of the bank slope or channel bed. Installation is faster than conventional concrete or boulder pitching and gabion laying. It delivers the durability and performance of concrete without the costly, time-consuming, and difficult installation process of conventionally formed concrete slope paving.
Recently, TechRevetment technology has been successfully applied in the Maheshkhali economic zone under BEZA (Bangladesh Economic Zone Authority) for Super Petro Chemical Complex Ltd. This Sea wall protection stretching more than 4 km has been constructed to resist Bay of Bengal tidal wave actions and embankment protection. Sirajgonj Economic Zone Authority has also constructed a 2 km long similar type of river protection with Techrevetment technology to protect the slope from the Jamuna River cub-channel. Both projects were completed within a much shorter time and cost than the conventional methods with better quality. They were implemented through a collaboration between Terre Armée, a French multinational, and Samuda Construction, a Bangladeshi enterprise. Terre Armée provided the technology, and Samuda Construction implemented the project. These two projects will be eye-openers for government and private enterprises in the coming days.
Draintube Drainage Geocomposite
Drainage systems are critical for a country like Bangladesh, where the soil is relatively soft and the rainy season lasts more than four months a year. Conventional drainage solutions are often not compatible, especially for road embankments, waste management (leachate collection system, landfill gas drainage, landfill closures, etc.), sports fields, and industrial purposes. Modern technology-driven ‘Draintube Drainage Geocomposite’ solution can be perfect here. It’s popular worldwide. Recently, a European company operating in Bangladesh incorporated this solution into its industrial premises.
Drainage multi-linear geocomposite with drainage conduits regularly spaced between two geotextiles instead of a geonet core helps the structures to release the excess water, leachate /gas. A lack of granular material near the site makes it necessary to use a draintube geocomposite. Typically, it consists of a needle-punched non-woven filter, polypropylene mini-pipes (regularly perforated according to a 90° dual alternated axis), and a needle-punched non-woven draining layer. However, the layers would differ based on the detailed design and actual requirement of transmittivity.
Slope Stabilization
Slope stabilization is a critical structural component. Passive and active solutions are required to address slope stabilization and mitigate damage due to slope failures. Earthen slopes are often exposed to aggressive environments and circumstances, such as underlying soil instability, heavy rainfall, snow accumulation, or seismic activity, that can compromise the stability of the earth’s mass. When left unchecked and not properly corrected, landslides and slope failures can be disastrous and cause severe damage. In Bangladesh, we encounter such landslides in our hilly and rural areas during the monsoon period.
A state-of-the-art technology for confronting such challenges is ‘TerraNail.’ The fundamental concept of TerraNail consists of reinforcing the soil or rock mass by passive inclusions, closely spaced, to create an in-situ coherent gravity structure. Hence, it increases the overall shear strength and stability of the in-situ soil or rock strata and restrains its displacements. TerraNail alone or combined with other slope stabilization techniques can be used to rehabilitate failed slopes and landslides. Installation of TerraNail for any permanent solution involves basic steps like drilling, placing the bars, grouting, and securing the nail end.
This technology is widely used in countries like Malaysia, Vietnam, Nepal, and many others and can be a very effective solution for our case.
Geo Reinforcement and Ground Stabilization
The stability of structures on soft soil, where basal reinforcement and challenging ground stabilization are needed to support building roads, bridges, embankments, runways, railways, working platforms, heavy-duty pavements, etc., is governed mostly by the foundation’s shearing resistance. Essentially, the construction of a heavy-duty structure on soft soil is a problem of bearing capacity.
A technology named ArmaLynk resolves this problem by reinforcing the soft soil and thus increasing its bearing capacity. ArmaLynk is a soil reinforcement geosynthetic manufactured from high-tenacity polyester yarns, extruded to form polymeric strips encased in polyethylene sheath, and welded together to cross strips to generate a stable and strong geogrid structure.
ArmaLynk’s design utilizes standard geotechnical practices to integrate strong unidirectional geosynthetic grids engineered to bear loads with minimum deformation. Compared with conventional methods like excavation and replacement, displacement, desiccation, progressive displacement, chemical stabilization, etc., ArmaLynk helps reduce the construction time and increases the project’s global performance.
Mechanically Stabilized Earth wall
Mechanically stabilized earth (MSE) walls are widely used in various applications in building roads, bridges, embankments, industrial landscapes, and more. The use of MSE walls is also increasing in Bangladesh, though it has not reached its potential in terms of diverse applications, cost-effectiveness, and architectural beauty. As one of its major components, the mold for the MSE wall is imported, it limits both the structural design and architectural exploration.
Recently, however, Samuda Construction has been pioneering the advancement of MSE wall solutions in Bangladesh. The company manufactures mold locally, which has enabled the project owners to explore diversity in design and architectural looks. In a recently completed project at the Dhaka-Gaibandha highway, the company constructed the MSE walls with the Roads and Highways Department logo. It was the first instance of such customized MSE wall projects displayed in Bangladesh.
Apart from these, some other technological products can be named where immediate tangible outcomes can be achieved regarding sustainability, cost, and construction timeline. The rhetoric of corruption being the only reason for our construction projects to be over budgeted, delayed, and below quality standards is actually a partial truth. The most significant reason we failed to achieve the right results is not adopting the right technology and the rigidity among the key decision-makers to explore technologically advanced products. We must press hard to change this mindset and build the capacity of our decision-makers, engineers, and other stakeholders to adopt and implement advanced technological products in our construction works to achieve the vision of being a developed country by 2041.
