Resilient rural road construction in Thailand using MIRAFI H2Rx geotextile 

Overview

The Department of Rural Roads (DRR), under Thailand's Ministry of Transport, plays a pivotal role in advancing the country’s rural transportation network. As a key stakeholder in the planning, design, construction, and maintenance of rural roads, the DRR is committed to ensuring safer, more efficient travel routes that support economic development and social connectivity in rural communities. Their focus is not limited to basic infrastructure; they also emphasize sustainable practices, flood mitigation, and the enhancement of transportation systems to support local and regional growth. 

This project was initiated to improve the safety and functionality of an existing rural road segment, which serves as a vital access point for nearby communities. Located in a low-lying clay rice field prone to water accumulation, the route was vulnerable to damage and flooding due to its soft soil composition and high groundwater levels. The project's primary goal was to construct a new segment and elevate an existing section of the road to ensure better drainage, enhance structural integrity, and provide year-round accessibility. 

Project execution required a multifaceted approach, including site preparation, elevation through controlled filling, asphalt paving, geotextile reinforcement, and installation of effective drainage systems. Additionally, traffic management solutions were necessary due to the road’s importance as a daily access route. The entire construction was scheduled for completion within 150 days, requiring collaboration between the DRR design engineers and implementation partners. The resulting infrastructure would deliver long-term benefits to the client, the local environment, and the community by ensuring flood resistance, transportation efficiency, and structural durability. 

Challenge

Given the geotechnical characteristics of the project area – namely, soft clay soils with a high water table – roadway instability and frequent degradation were longstanding concerns. The existing road alignment traversed agricultural land prone to saturation and waterlogging, necessitating not only structural reinforcement but also an effective drainage design to manage seasonal water accumulation. Moreover, the road could not be fully closed during the construction period, as it served as a key transit route for surrounding villages and agricultural operations. 

The initial phase of construction began with excavation along the road shoulder to ensure continuity between the old and new segments. The subgrade was then built up by placing engineered fill to raise the alignment to the design elevation. Simultaneously, the surface of the existing road was excavated to match the newly elevated fill. One of the central installation activities involved placing geotextile material – specifically designed for reinforcement and separation – beneath the base layer before asphalt paving commenced. 

Traffic management posed a considerable operational challenge. Complete closure was not viable, so a phased approach was adopted. Traffic lanes were partially closed and redirected with minimal disruption to the local populace. This required careful coordination and communication with the community and the engineering teams on-site. Wet weather conditions and the saturated nature of the subgrade further complicated operations, necessitating materials and techniques that could perform reliably in a high-moisture environment. 

Despite these constraints, the team delivered an innovative and time-efficient solution by integrating a geosynthetic material designed for challenging subgrades. The MIRAFI^® H2Rx geotextile, known for its unique combination of reinforcement and moisture control properties, was key to overcoming the geotechnical hurdles without extending the project timeline or compromising safety. 

Solution

To address the structural and hydrological challenges posed by the site, Solmax supplied 15,750 m² of MIRAFI H2Rx geotextile. This high-performance geosynthetic product was selected due to its dual-function capability: enhancing the tensile stiffness of the base course while also actively managing the moisture content within the pavement structure. MIRAFI H2Rx is engineered to provide mechanical reinforcement by distributing loads and reducing rutting, which is particularly important in weak subgrade conditions like those found in clay fields. 

Additionally, its wicking properties allow the geotextile to exert internal suction, thereby lowering the equilibrium moisture content of the surrounding basecourse. This contributes to improved compaction, higher bearing capacity, and prolonged pavement life – all without requiring chemical treatment or complex drainage layers. The effectiveness of the geotextile was demonstrated through its rapid deployment across 3 km of road, completed in just eight days. This swift installation enabled the construction team to maintain momentum, meet milestones, and mitigate traffic disruption. 

No alternative products were considered for this project due to the high-performance specifications required for the unique conditions. The decision to use MIRAFI H2Rx was based on its proven effectiveness in soft soil applications, as well as Solmax’s established track record and trust with the Department of Rural Roads. The engineering support provided throughout the planning and construction process further reinforced confidence in the solution. 

The geotextile was placed directly onto the prepared subgrade after excavation, providing immediate separation between the clayey soil and the aggregate base. This ensured uniform load distribution and minimized the risk of intermixing, which often leads to structural failure in wet conditions. Following placement, the base layer was compacted and paved with asphalt, with the geotextile providing consistent performance under both static and dynamic loads. 

Solmax’s involvement in the project went beyond product supply. Technical experts supported installation oversight, ensuring that material handling, placement, and coverage met design standards and manufacturer guidelines. The seamless integration of engineering support, material availability, and product performance contributed to the timely completion of the road segment. 

In conclusion, this rural road upgrade project exemplifies how advanced geosynthetic solutions can address structural challenges in areas with soft subgrades and high water content. The Department of Rural Roads benefitted from a time-saving, technically robust solution that did not compromise road accessibility during construction. The use of MIRAFI H2Rx ensured mechanical reinforcement and moisture control, directly contributing to pavement durability and long-term performance. 

The successful outcome of this project underscores three primary reasons why the client would recommend Solmax: the reliability of its branded solutions, the efficiency of installation, and the excellence of its technical services. These factors not only helped achieve a high-performance roadway but also reinforced a trusted relationship between the engineering team and product supplier. As the region continues to develop, such solutions offer scalable, sustainable options for resilient infrastructure across Thailand’s rural transportation network.