More Durable Concrete: The Need & The Rationale

 

Concrete is the most widely used material of construction, with a consumption rate of 22 billion tons/yr. Production of concrete accounts for more than 4 billion tons/yr CO₂ emissions and 20 billion GJ/yr energy use, most of which is associated with the manufacturing of cement. The concrete-based infrastructure supports diverse economic and social activities. The sustained growth in cement consumption over several decades reflects upon the buildup of an immense concrete-based infrastructure. Aging of this infrastructure has mounting economic and safety implications. 

While concrete occupies a significant volume of vast infrastructure systems, the expenditures on concrete materials constitute a relatively small fraction of the total infrastructure costs. Deterioration of concrete and corrosion of reinforcing steel under weathering, thermo-mechanical and chemical effects are key factors governing the maintenance and repair requirements and service life of the concrete-based infrastructure. More durable concrete materials would thus yield improportionally large life-cycle benefits. The improved service life of the concrete-based infrastructure would also translate into reduced CO₂ emission and energy use, which would be magnified if Portland cement is replaced with a cementitious binder of reduced carbon footprint and energy content.

Deterioration of concrete and corrosion of the reinforcing steel are complex phenomena. Concrete is prone to microcracking at young age, primarily due to the internal and external restraint of shrinkage movements. The pore structure of concrete together with these microcracks facilitate transport of moisture, aggressive solutions and gases into concrete. These transport phenomena facilitate various mechanisms of concrete deterioration, including freeze-thaw damage, alkali-aggregate reaction, sulfate attack, carbonation, acid attack, and corrosion of the reinforcing steel. These deterioration mechanisms together with the growth of microcracks and cracks under mechanical (including fatigue) loading and restrained dimensional movements compromise the barrier qualities and accelerate the degradation of concrete. Abrasion, erosion and cavitation are also among the mechanisms of concrete degradation in such concrete-based infrastructure systems as pavements and hydraulic structures.

A Case for High-Performance Concrete

Various high-performance concrete materials with excellent strength, durability and barrier qualities are now available to us. Examples include high-strength concrete and ultra-high-performance concrete. Their initial costs tend to be higher than normal concrete. Concrete materials, however, account for a minor fraction of the total construction costs of most infrastructure systems. Adoption of high-performance concrete thus does not have a notable effect on the initial cost, but significantly benefits the service lives and reduces the maintenance costs of diverse infrastructure systems.

Some Major Branches of Civil Engineering

Civil engineering, concerned with the construction, design, and upkeep of physical environments, is one of the world's oldest professions. It involves the construction of dams, highways, sewage, and bridges.

Projects in civil engineering require a high understanding of mathematics and physics because they involve the construction of complex everyday structures used on a large scale. As a result, civil engineering projects may be divided into five categories: geotechnical engineering, structural engineering, transport engineering, construction and management engineering, and water engineering.

Geotechnical engineering is one of the five branches of civil engineering that is concerned with understanding how a project interacts with the earth. Geotechnical engineers work on constructions such as bridges, highways, and trains, among other things.

For each project, geotechnical engineers deal with a distinct type of ground. The geotechnical engineer's task is to determine how it will interact with the project, whether it's built of soil or rock. Most geotechnical engineers are ecstatic about this since no two grounds are the same.

The construction and management branches of civil engineering is concerned with constructing bridges, roads, buildings, etc. The construction branch aims to create these buildings in the most efficient, safe, long-lasting, and environmentally friendly manner feasible. This is why it relies greatly on mathematics and physics to calculate and ensure the efficiency level of each structure. The management branch covers the phase that follows construction . This phase outlines the project's maintenance, operation, and renovation during its lifetime. These elements must be handled so that the project's owner can ensure that the expenditures on the project are used efficiently and effectively.

Like construction and management engineering, structural engineering is based on math and physics. A structural engineer's profession includes analyzing and designing bridges, towers, buildings, dams, and other structures. These buildings must be constructed to be safe, long-lasting, cost-effective, and visually appealing.

Engineers can use math and physics to assess if all sections of a project are strong enough to withstand loads, calculate the structure's service life, and determine if the structure is stable. Structural engineering is the most important of the five branches of civil engineering in terms of design and material selection.

Transportation engineering is concerned with the planning, design, and operation of massive transportation networks. This branch encompasses various modes of transportation, including air, sea, road, and train.

Transportation engineering is one of the five categories of civil engineering; this branch continually seeks methods to improve our transportation systems. The work of a transportation engineer is to ensure that various modes of transportation satisfy specified requirements. Sustainability and safety are two standards that must be satisfied.

In addition, water engineering is a branch of civil engineering that studies how water behaves in both natural and man-made environments, such as beaches and rivers. It also comprises the creation and management of strategies, infrastructure, and equipment aimed at preserving and controlling this natural resource for human consumption.

Natural springs, underground wells, and water treatment facilities are primary topics that water resource engineers work on. Aside from managing and providing clean water, water resource engineering also entails the design and maintenance of sewage and wastewater disposal systems.