Faster & Better Road Construction is Possible
Dr. John Mukabi and Nick Muller give an analysis of the innovative characteristics of SoilTech MK. Ill, a polymer stabilized geomaterial for construction of pavements.
Road Transport & Highways minister Nitin Gadkari has time and again been urging to use more of innovative techniques and materials for faster and better-quality construction of roads and highways. While launching the country's first Highway Capacity Manual (HCM), he said that the government officials and departments should be more proactive in adopting superior stabilizing technologies that would speed up road construction significantly, while enabling better and more long-lasting roads.
HCM is a guide to road engineers and policy makers on road construction code, traffic management and construction capacity of highways. It is based on a countrywide study of traffic on different categories of roads and highways by CSIR-CRRI.
Challenges & Solutions
Stabilization techniques have long been used for purposes of enhancing the geotechnical engineering properties of pavement geomaterials. These techniques mainly include mechanical, traditional hydraulic (cement, lime, fly ash etc), bituminous, polymer and other non- traditional liquid chemical stabilization. Liquid chemical stabilization is yet to gain popularity due to lack of proper scientific and engineering background and pragmatic performance justification based on enhanced R&D. In due consideration, the main challenges associated with stabilization that require rigorous R&D include: i) Developing stabilization techniques that can be effectively useful for inferior construction materials that are usually rendered useless ii) Determining optimum batching ratios for varying geomaterials to enhance mechanical stabilization prior to application or addition of stabilizing agents iii) Selection of appropriate stabilizing agents that are chemically compatible with the applicable geomaterial iv) Determining the optimum content to be added to the geomaterial in order to achieve optimally enhanced physical and mechanical properties whilst minimizing associated detrimental effects such as cracking v) Developing sophisticated and advanced analytical modelling techniques that can effectively characterize the behaviour of stabilized geomaterials both quantitatively and qualitatively. In this study, sophisticated analytical models are employed in characterizing and fostering the salient properties of SoilTech Mk. Ill polymer stabilizing agent
"There is an urgent need to give up conservative approach in governance and adopt new technologies to push the pace of highway construction." Nitin Gadkari, Road & Highways Minister
with respect to theoretical and pragmatic consideration including: a. Interlayer nano-polymer migration effects b. Elastomeric properties c. Enhanced response to compaction effects
d. Enhanced tensile characteristics vi) Increased resilience to deformation; vii) Expanded range of stress-strain elastic
limits; and, viii) Appreciable resistance to cracking under excessive loading
SoilTech Mk. III - a third generation soil stabilizer, was developed 20 years ago in by Polymer Pavements in South Africa, and is currently represented in India by J.V partner Kaveri Ultra Polymers. SoilTech was purposely designed and manufactured to address these challenges and to leapfrog somewhat archaic road stabilization technologies.
• 1998: the first commercial application of SoilTech Mk. I was in 1998. Initially, the product was developed as a binder for rural roads. Over the next couple of years, Polyroads modified SoilTech with new cross-linking polymers to improve compressive strengths – SoilTech Mk. I.
• 2006: major technology advances saw the introduction of long-chain polymers into SoilTech and thereby adding a second performance dimension to SoilTech. The high CBRs achieved in materials with SoilTech were complemented by new and highly improved elastic modulus in the stabilized pavements, allowing greater flexural strengths and loading capabilities, not to mention improved longevity in the pavements – first of a kind - SoilTech MK. II.
• 2010: Polyroads chemical engineers introduced nano-polymerization into SoilTech. The specific nano-polymers being substantially smaller than the normal SoilTech polymer particle, allows for easier sliding velocity on capillary adhesion in the materials. Specifically engineered surfactants, mixed with the nano-polymers, further reduces tensions as SoilTech nano-particles migrate from the stabilized base-layer into the subbase, resulting in two-layer stabilization. First of a kind – SoilTech Mk. III.
Polyroads’ engineers have developed appropriate methods of design involving advanced geotechnical engineering concepts related to the Elastic Limit Design Criterion (ELDC) and Modulus-Thickness Design Criterion (MTDC). The prowess of these methods, developed for both unreinforced and stabilized pavements, with fundamental objectives of achieving prolonged pavement design life through protracted maintenance of the elastic properties, is demonstrated by ensuring that the impact of imposed loads and environmental changes is contained within the linear elastic region.
The most distinguished advantage of the ELDC and MTDC, is that all design parameters derived are based on only three primary parameters; namely, the pavement thickness, elastic modulus and the cumulative ESALs (Equivalent Single Axle Loads), to which all other parameters are correlated. Non-linearity is analysed based on the soil mechanics concepts of the KHSSS (Kinematic Hardening Small Strain Stiffness). Due to the successful application and cost-construction time effectiveness of these methods of design, Polyroads’ engineers will advise on the application of the elastic limit stress-strain and modulus-thickness ratio concepts as the appropriate quasi-mechanistic methods of design for polymer stabilized pavement geomaterials.
More than 20 roads have already been constructed in India using SoilTech Mk. III stabilizers. SoilTech.
I. Reduce aggregate required for layered
II. Reduce construction time
III. Reduce costs
IV. Improve road longevity.
iTRARR 2018 - International Conference – Mombasa, Kenya
The Kenya Roads Board in collaboration with Material Testing and Research Division will host the 2nd International Conference on Transport and Road Research (iTRARR 2018) from 11 – 14 June in Mombasa, Kenya. Dr. John Mukabi will be presenting a Paper on ‘Innovative Analytical Characterization of SoilTech MK. III Polymer Stabilized Geomaterials for Unique Design and Construction of Pavements’, at the conference. http://www.transportconferencekenya.org/#about
Table 1: Chronology of 3rd Generation Stabilizer