Concrete Pathology in Civil Construction: From Diagnosis to Structural Rehabilitation

Patologia do Concreto na Construção Civil: Do Diagnóstico à Recuperação Estrutural

In diagnostic engineering, we often say that structures "speak." Before a collapse or serious functional failure, concrete emits clear signs of degradation.

Understanding concrete pathology in civil construction is not just a matter of corrective maintenance; it is an imperative for the safety, durability, and economic viability of real estate assets.

In this technical article, Novakem delves deeper into the discussion initiated by major market players to deliver an analytical overview of the pathological manifestations that most affect the performance of Brazilian buildings.

What is Pathology in Civil Construction?

The term "pathology," borrowed from medicine, refers to the study of diseases. In engineering, it is the science that studies the origin, symptoms, and nature of failures in buildings. According to NBR 15575 (Performance Standard) , a building must maintain its integrity and functionality throughout its Design Service Life (DSL). When this does not occur, we are faced with a pathological manifestation.

Pathologies can compromise everything from aesthetics to the overall stability of the structure. Industry data indicates that correcting a defect during the use phase can cost up to 125 times more than if it had been prevented during the design phase (Sitter's Law).

Patologia do Concreto na Construção Civil

The Triad of Causes: Where Does the Problem Begin?

Although the blame often falls on the material, technical literature and field practice show that concrete pathology in civil construction is multifactorial.

We can categorize the origins into three main groups:

1. Design Flaws (The Silent Origin)

Design flaws are responsible for a significant portion of the problems. This includes:

• Insufficient reinforcement detailing: Failure to account for cracking due to shrinkage or thermal gradients.

• Inadequate specification of fck: Ignoring the environmental aggressiveness class (CAA) of NBR 6118, resulting in concrete with porosity incompatible with the environment.

• Lack of compatibility: Conflicts between structural and installation designs that lead to improper cuts in beams and slabs.

2. Execution and Material Errors

The construction phase is critical. Common problems include:

• Poor curing: Lack of adequate hydration in early stages results in porous and permeable concrete, an entry point for aggressive agents.

• Segregation and exudation: Caused by excessive vibration or poorly calibrated mix (excess water/cement).

• Insufficient concrete cover: Disregarding spacers leaves the reinforcement exposed to chloride attack and carbonation.

3. Improper Use and Maintenance

Unforeseen overloads in the original design and lack of preventive maintenance (facade cleaning, waterproofing inspection) accelerate degradation.

Main Pathological Manifestations of Concrete

For an accurate diagnosis, it is essential to differentiate the symptoms. Below, we detail the most critical occurrences faced by Brazilian engineers.

Cracks, Fissures and Fractures

These are the most visible manifestations. Technically, they are differentiated by their opening and activity (active or passive).

• Cause: They can arise from plastic shrinkage (rapid water loss), thermal shrinkage (heat of hydration ), foundation settlement, or overloading.

• Diagnosis: The mapping should identify the direction and depth. Cracks at 45º in beams, for example, indicate shear and require immediate intervention.

Fissuras, trincas e rachaduras na estrutura de concreto

Armor Corrosion

It is the leading cause of deterioration in reinforced concrete structures worldwide. It occurs when the passivating layer of the steel is destroyed.

• Carbonation: CO₂ from the atmosphere penetrates the pores of the concrete, reacting with calcium hydroxide and reducing the pH (from ~12.5 to < 9). Without alkalinity, the steel corrodes.

• Chloride Attack: Common in marine areas. Chloride ions penetrate the concrete and attack the steel in a localized manner (pitting), being extremely dangerous because they do not present visible external signs until advanced stages.

Carbonatação (corrosão) de estrutura de concreto

Alkali-Aggregate Reaction (AAR)

An expansive chemical reaction between the alkalis in the cement and certain reactive minerals present in the aggregates.

• Symptom: Map-shaped (cracked) fissures and exudation of an alkaline silica gel.

• Impact: It generates internal stresses that disintegrate the concrete from the inside out.

Leaching and Efflorescence

Water travels through the concrete, dissolving and transporting compounds (such as calcium hydroxide) to the surface.

• Consequence: In addition to the aesthetic white stain (efflorescence), leaching increases the porosity of the concrete, reducing its mechanical strength and durability.

Prevention and Therapy: The Novake Approach

Combating concrete pathologies in civil construction requires technology. Prevention begins with choosing a low-permeability, high-performance concrete, strictly adhering to the water/cement ratio.

For structures already affected, therapy involves:

1. Diagnosis: Non-destructive testing (sclerometry, ultrasound) and core sampling.

2. Steel Treatment: Mechanical cleaning and application of corrosion inhibitors .

3. Reconstruction: Use of polymer mortars or grouts with high strength and low shrinkage.

4. Protection: Application of surface protection systems (water repellents or technical paints) to block the entry of new aggressive agents.

Conclusion

The durability of our cities depends on the quality of our concrete and the seriousness with which we address its structural problems. Ignoring small signs today is inviting great losses tomorrow.

At Novakem , we understand that every project is a living organism. Our solutions are developed to ensure that the structure not only withstands the elements, but performs with excellence for decades.