Highway Construction Technology · Engineering Sectors
Expressway construction technology refers to a complete set of technical methods and standards covering design verification, material selection, process control, quality inspection, and safety management, applied throughout the entire construction process of expressway projects—including subgrade, pavement, bridges and culverts, tunnels, traffic safety facilities, and electromechanical systems. Its core objective is to ensure that expressways possess sufficient strength, stability, durability, and driving safety under operating conditions of high traffic volume, high vehicle speeds, and heavy loads.
Regarding the background of its development, the formation of the expressway construction technology system is closely related to three factors:
1. Increased Traffic Load and Speed Requirements: Expressway design speeds typically range from 80–120 km/h, with a high proportion of heavy-load traffic, imposing far higher requirements on subgrade settlement, pavement smoothness, and skid resistance than ordinary highways.
2. Demand for International Engineering Contracting: Chinese state-owned enterprises undertake numerous overseas expressway projects along the "Belt and Road," requiring simultaneous compliance with Chinese standards, international standards (such as AASHTO, BS, EN), and local regulations of host countries—driving the construction technology system toward compatibility and modularization.
3. Advances in Materials and Equipment: Technological iterations in large-scale pavers, intelligent compaction systems, warm-mix asphalt, modified asphalt, and high-performance concrete have transformed construction technology from an experience-based approach to a data-driven one.
The scope of application covers: subgrade works, pavement works (asphalt/cement concrete), bridge and culvert works, tunnel works, drainage and protection works, traffic safety facilities, and electromechanical works for both new construction and reconstruction/expansion of expressways. It applies to both domestic projects in China and overseas EPC/DB turnkey projects in technical planning, construction organization, and quality control.
> Note: For specific standard numbers (such as JTG, AASHTO, EN, etc.), please refer to official documents. This article does not fabricate numbers.
The subgrade is the "skeleton" of an expressway, and its settlement control directly determines pavement service life. Key control points are as follows:
| Control Item | Key Technology | Common Issues |
|---|---|---|
| Fill material selection | CBR value, maximum particle size, moisture content control | High liquid limit soil and expansive soil require improvement |
| Compaction degree | Layered filling, intelligent compaction, sand replacement method testing | Insufficient compaction leads to post-construction settlement |
| Drainage | Combination of side ditches, blind drains, and infiltration trenches | Poor drainage causes mud pumping |
| Special subgrade | Soft ground treatment (preloading, CFG piles, prefabricated vertical drains) | Soft ground settlement exceeds limits |
Checklist: Key Actions for Subgrade Construction
Pavements are divided into two major categories: asphalt pavement and cement concrete pavement. Overseas projects are predominantly asphalt pavement.
Core of Asphalt Pavement Construction:
Core of Cement Concrete Pavement:
| Engineering Type | Key Technology | Quality Control Focus |
|---|---|---|
| Bridges | Pile foundations, pier columns, beam prefabrication/cast-in-place | Pile integrity, concrete strength |
| Culverts | Pipe culverts, box culverts, slab culverts | Foundation bearing capacity, joint waterproofing |
| Tunnels | Drill-and-blast method, shield method, New Austrian Tunneling Method | Surrounding rock stability, initial support, waterproofing layer |
Special Notes for Tunnel Construction:
| Inspection Item | Method | Frequency |
|---|---|---|
| Compaction degree | Sand replacement method, nuclear density gauge | At least 1 point per 200 m per layer |
| Smoothness | 3 m straightedge, IRI | Per lane per 200 m |
| Thickness | Core drilling, ground-penetrating radar | At least 1 point per kilometer |
| Strength | Core drilling, rebound hammer | Per specifications |
> For specific inspection frequencies and indicators, please refer to the host country's specifications or contract technical clauses.
| Comparison Dimension | Chinese National Standards (JTG Series) | International Standards (AASHTO/BS/EN) | Local Standards (e.g., Africa/Southeast Asia) |
|---|---|---|---|
| Design philosophy | Strength-based control | Performance-based control | Mostly inherited from colonial-era standards or national specifications |
| Subgrade compaction | Compaction degree control | Relative density/modulus control | Mixed control |
| Asphalt pavement | Marshall design method | Superpave/performance-based design | Mostly Marshall or simplified methods |
| Bridge loads | Highway Class I/II | HL-93/BS 5400 | Mostly referencing AASHTO or BS |
| Testing methods | Sand replacement, core drilling | Nuclear density, FWD | Depends on equipment availability |
Practical Tip: Overseas projects often encounter a triple overlap of "contract requiring AASHTO, owner accustomed to BS, and local materials conforming to Chinese standards." Standard benchmarking and material adaptation must be completed during the technical planning phase.
This project is located in a high-altitude area with complex geology, facing challenges such as rockbursts, freeze-thaw cycles, and landslides. Technologies such as advanced geological prediction, enhanced initial support, and controlled blasting were adopted during construction, demonstrating the adaptability of expressway construction technology in extreme environments.
Although the Mombasa-Nairobi Railway is a railway project, its supporting highways and expressways along the route involve soft ground treatment, asphalt pavement construction, and other technologies, showcasing the practice of aligning Chinese standards with local standards.
In the hot and rainy region of Southeast Asia, asphalt pavement construction requires focused control of temperature segregation and moisture damage. The adoption of modified asphalt, warm-mix technology, and strict drainage design represents a typical tropical application of expressway construction technology.
> The above projects only cite publicly reported information. For specific technical details, please refer to official documents.
Q1: Should overseas projects prioritize Chinese standards or international standards?
A: It depends on the contract provisions. If the contract explicitly adopts AASHTO or BS, those shall prevail. If not specified, a Chinese standard proposal can be submitted during the technical planning phase, but requires approval from the owner and supervising engineer. It is recommended to prepare a standard benchmarking table.
Q2: What should be done if compaction degree testing methods are inconsistent?
A: Communicate with the supervising engineer in advance to determine the testing method and frequency. The sand replacement method and nuclear density gauge can be used simultaneously for comparison to establish a correlation.
Q3: How can early damage to asphalt pavement be prevented?
A: Focus on controlling mix design, paving temperature, compaction degree, and joint treatment. In tropical regions, additional measures for moisture damage resistance and rutting resistance are needed.
Q4: How should weak surrounding rock be handled during tunnel construction?
A: Adhere to the principles of "short advance, weak blasting, strong support, quick closure," and adopt pre-support measures such as advance small pipes and pipe roofs when necessary.
Q5: How should local materials that do not meet specification requirements be handled?
A: First, conduct material testing and mix proportion optimization. If requirements are still not met, apply for design changes or adopt improvement measures (such as adding cement, lime, or modifiers).
1. Standard benchmarking first: Complete three-way benchmarking of Chinese standards, international standards, and local standards at the project initiation stage, and produce a "Technical Standards Comparison Table."
2. Localized material testing: Conduct systematic testing of local aggregates, asphalt, and cement to establish a localized mix design database.
3. Intelligent compaction and informatized construction: Introduce intelligent compaction and GPS paving control in subgrade and pavement construction to improve quality consistency.
4. Climate-adaptive design: Strengthen drainage and moisture damage resistance in hot and rainy regions; control freeze-thaw and low-temperature construction in cold regions.
5. Supervision communication mechanism: Establish regular technical clarification meetings to resolve standard discrepancies and acceptance disputes in advance.
6. Settlement observation and post-construction assessment: Settlement observation must be installed in soft ground sections, and pavement construction can only proceed after post-construction assessment passes.
7. Training and briefings: Conduct tiered technical briefings for local laborers, with Chinese personnel supervising key processes.
8. Documentation trail: All inspections, acceptances, and changes must be recorded in writing to meet contract and audit requirements.
> For specific standard numbers, project amounts, and technical parameters, please refer to official documents or contract technical clauses.