Jute-reinforced fibre is an emerging new material that offers compressive strength and arrests crack propagation in structures, explores AHLAM RAIS.
In the past few decades, various materials have emerged to ease the construction process. Jute-reinforced fibre is one such material developed at IIT- Kharagpur in West Bengal that offers compressive strength and arrests crack propagation in structures. Compared to glass or polymer fibres, jute-reinforced fibre is renewable in nature and the energy used to melt the glass or manufactured polymer can be saved. The material also proves beneficial for low-cost housing under the Indira Vikas Yojana Programme. Professors at IIT-Kharagpur Subhasish Basu Majumder and Basudam Adhikari, who have tested and experimented with this material in various applications, elaborate upon the various facets of jute-reinforced fibre...
In the mix
Jute-reinforced fibre is about 2-3 m long and is cut into small fibres of about 4-6 mm. These fibres are then chemically treated to increase stability. It contains 13-15 per cent lignin and 60-65 per cent cellulose; the rest is hemicellulose and a few other soluble sugars. During the chemical treatment, hemicellulose and the other sugars including lignin are removed, which loosens the fibrils and the cellulose molecules; that is, fibre gets fibrillated into fibrils. These fibrils contain cellulose molecules and between these molecules are hydroxyl groups that are bonded together with hydrogen. These hydroxyl groups interact with cement in the concrete, and in the process, bonding with polymers and chemicals takes place. Polymer acts as a bridging agent between this fibre and cement. Following this, a matrix of concrete comprising cement, sand and stone in the form of coarse and fine aggregates is produced. The chemically treated material is then dispersed in the concrete mixture. After setting, the concrete is cured for 28 days, which results in enhancing strength. With normal concrete-making technology, you may not be able to disperse this jute fibre into the concrete efficiently; you need a shear mixture that will offer two purposes: it will have a homogeneous dispersion of the fibres into the cement matrix, and owing to the shearing action, it will bring out the fibrils in a nano-dimension through which strength will improve dramatically.
Operations and functions
We have used jute-reinforced fibre in a variety of products. It can be used in bricks to develop houses for the poor. These bricks are mixed with fly-ash and cement and prove to be an excellent alternative to normal clay bricks. As fly-ash does not have its own binding property, it has to be dispersed with jute-reinforced fibre. To enhance its strength, these jute bricks are sprayed with water so they become hydraulic in nature. Today, all wooden and steel sleepers have been replaced by concrete sleepers. We constructed around 20 railway sleepers by incorporating this material for BG sleepers in Rajasthan. On testing, we found that jute-fibre reinforced concrete that contained steel displayed more strength than normal concrete.
It can also be utilised in electric poles, irrigation and sewage pipes. Generally, electric poles break down owing to high wind pressure as they are brittle in nature. However, with the inclusion of this material, the deflection is fantastic. Another point that should be highlighted is that when we work with RCC concrete, steel is used as a cage in pipes. Once jute-reinforced fibre is used, one can reduce the consumption of steel by about 30 per cent and achieve the same strength. In fact, the material offers about 16 per cent more strength.
Jute-reinforced fibre can also be used effectively in pavers when mixed with fly-ash and cement. It can also be used effectively as plaster. However, there is a distinction between plaster materials. The plaster is in the form of a mortar; we do not use stone chips.
In fact we only use sand, cement, water and jute-reinforced fibre. In case of a concrete-based product, we utilise cement, sand and stone chips along with jute fibre; for RCC concrete, steel is used as a secondary reinforcement and for pre-stressed concrete, steel bar in tensile condition is used.
Jute-reinforced fibre increases compressive strength. It has high load-bearing capacity and reduces the use of steel by about 30 per cent. It also proves beneficial in seismic zones; during an earthquake, the cracks experience a dampening effect and hold the structure together for a longer period of time. We conducted several tests to study the MoR (Modulars of Rupture) value and CCS measurements (Cold Crushing Strength). The fibre used in the plaster arrests crack propagation and reduces catastrophic failure of the concrete.
We have used jute-reinforced fibre across diverse products and the level of deterioration has been negligible. Roughly, we project this material to have a life of at least 30 years. We have done a primitive cost analysis but as it is a value-added product, you will have to consider a marginal cost. A cost improvement of about 5-7 per cent will be present. We are in the process of patenting this technology and planning to sell this material to developers.
People have to look out for alternate sources to keep the environment green. Jute-reinforced fibre is a natural resource and, through this, the jute, cement and construction industry will receive a mega boost.
After speaking to industry leaders on the efficacy of jute reinforced fiber as a construction material, CW contacted Subhasish Basu Majumder and Basudam Adhikari for clarifications.
On loading factor or load distribution of this material:
If we relate the loading factor of this material to the amount of fibre incorporated, we will receive the best result in about 1 weight per cent (with respect to the amount of cement used) modified jute fiber reinforced concrete. Since most of the MoR (modulars of rupture) tests were performed in a three point bending configuration, the load was the maximum at the mid-span and it drops linearly to zero at the two end supports.
On existing material jute reinforced fibre replace:
Traditional concrete is less ductile as compared to jute fiber reinforced concrete. Lately, we have found that jute fibre can also replace traditional fibre like asbestos in building materials. The products made o