Concrete Vs Steel In Construction: Pros And Cons

Pros and Cons of Concrete

Concrete components are mostly available in most areas. Chances of cracks and blemishes in concrete are minimal. Concrete may be enhanced to adequate strength at a minimal cost. Concrete is very long-lasting. Concrete can be molded into any shape or structure. The expense of concrete maintenance is nearly non-existent. The degradation of concrete with age is negligible. Concrete is wind and completely waterproof. As a result, it is quite beneficial in storm shelters. Cinder concrete might be utilized as a soundproofing material.

The tensile strength of concrete is comparatively lower than other binding materials. Ductility in regards to concrete is very much low. On assessing it is observed that the weight of concrete I comparatively more than its overall strength. Efflorescence is caused by soluble salts, which are present in concrete.

It is to be noted that the tensile strength and the strength to weight ratio of steel is comparatively high, which as a consequence enhances the strength per unit mass. Hence, it can be comprehended that different parts of steel are very much compressed and light-weighted (Mahajan & Sidhu, 2018).  It is observed that the process of manufacturing steel is very much simple and concise. The components of steel are at first manufactured in the factory and then assembled on the site. Consequently, it contributes to optimal utilization of time and money (Yang et al., 2018).

Since Steel is an iron alloy, the chances of corrosion are very much high. Hence, it is highly suggested to use Anti-corrosion applications to resolve this issue to some extent. It is observed that the fireproofing expenses involved in the manufacturing of steel are comparatively higher as it is not fireproof.

Strength- It is observed that concrete is a popular building material that is extremely strong in tension and compression.

Economical- It is noticed that the concrete materials are readily accessible and reasonably priced over the world. Moreover, the overall expense incurred in manufacturing concrete is quite low. The implementation of reinforced concrete saves money in the long run as the overall maintenance expense is very much low.

Durability- It is to be noted that if the concrete is designed accurately and properly, it will serve the long run.  Moreover, it is also noticed that the harsh weather condition are not able to adversely affect concrete, hence it can be said that it is the most sustainable material to be used in the long run.

 Fire Resistance- The materials evolved in building concrete to protect it from fire accidents. It is observed that the materials used are able to survive extreme heat for more than 6 hours. Furthermore, it is also noticed that building materials involving concrete are more fire-resistant than building materials using steel.

Inspection of formwork erection for concrete structures

All formwork material is in good condition, composed of sound material with an appropriate strength, and is properly braced, strutted, and shored to maintain rigidity throughout the laying and consolidation of the concrete with no obvious deflection. To avoid cement slurry loss, every formwork must be waterproof. Formwork must be built to ensure that the concrete has the exact form, line, and proportions as depicted in the designs. Shutter boards and neighboring shutters are correctly aligned and sealed over as needed. Water stops must be installed in joints where waterproof construction is needed, and the water stops must be as depicted in the design. All grooves, corner chamfers, and so on have been properly placed. Joint filler strips must be constructed from cellulose fibers or cork that is firmly held together by a suitable asphaltic binder sponge, rubber, or PVC as specified in the designs (Wang et al., 2018). The surface of the formwork is carefully cleaned of any dirt, mortar, and foreign materials before being covered with the release agent.

Pros and Cons of Steel

Inspection of steel reinforcement receiving, fabrication, and installation

Material inspection is required prior to cutting and bending of reinforcement. The factory test certificate for the accepted delivery schedule and batch must be accessible at the material inspection location. To assure the quality of reinforcement, appropriate tracing must be supplied. Fusion Bonded Reinforcing Steel must be used for reinforcement as specified by the project. Reinforcing steel should be kept over wooden battens to avoid soil contact and shall be covered to avoid air contact. Reinforcing steel storage, cutting, bending, and fastening must all be done in accordance with project specifications (Huang et al., 2020).

The designated third-party field technician is responsible for monitoring concrete receipts and obtaining a copy of all concrete delivery notes. Truck mixing is permitted if the concrete cannot be discharged within 90 minutes.

Prior to putting concrete, the QC Inspector must inspect the cleaning of tie wires, nails, bits of wood, and wind-blown sand. A minimum of two concrete vibrators/pumps must be present on-site for each concrete installation, as well as flexible hoses for concrete placement on walls. Concrete should be laid in horizontal layers no deeper than 450mm. Concrete shall not be dumped freely where strengthening will not produce separation, nor shall it fall freely for more than one meter.

Formwork removal- Formwork must be removed in such a way that it does not harm the concrete. No forms must be removed until the concrete has become strong enough to sustain itself. When the part being sustained has grown adequate strength to bear itself and the weight put on it with an acceptable factor of safety, the centers and props can be withdrawn.

Concrete surface inspection- Following formwork removal, the Civil Quality Control Inspector must check the concrete surface and quickly advise the Section / Site Engineer of any locations requiring corrective work. And the ultimate approval of concrete should be verified after the concrete's strength test after 28 days.

Curing of concrete- Water curing must be done continuously until the compressive strength reaches 70% of the prescribed strength, but no later than 7 days after installation, and must be done by covering with wet burlap and plasticized sheet.

According to the image, a few portions of the concrete break loose from the structure, exposing the concrete reinforcement to the atmosphere. It's a phenomenon known as concrete spalling. Spalling is produced by chemical processes inside the concrete that result in the creation of large amounts of foreign products. Because of the shortage of room inside the concrete, these new items will raise internal pressure.

Freeze-thaw cycles- In cold weather zones, seeping water condenses into ice, which has a larger volume than water.

Alkali Aggregate Reactions- When the alkali in the cement combines with the silica in the aggregates in the presence of water, the Alkali Silica Gel (ASG) is formed, which has a larger volume than traditional hydration products (Lanko et al., 2018).

High Temperature- Explosive spalling can occur during a fire or when concrete is subjected to high temperatures, resulting in high pore pressure caused by oversaturation. Due to its enhanced brittleness, high-strength concrete is more prone to failure at high temperatures than regular strength concrete.

Inspection of Formwork Erection

Improper Compaction- Improper compaction may reveal the reinforcements to the climate, causing rusting and spalling.

Improper Water content- Low water content reduces workability and makes compaction difficult. This may result in the production of unexpected air pockets, which may eventually contribute to the formation of cracks. A high water-cement ratio reduces the strength of the concrete, making it more susceptible to tiny fractures and, as a result, spalling.

Sulfate Attack- It is caused by sulphate-rich cement or sulphates in the environment. The degradation of the hydration byproducts reduces the strength of the concrete and so produces spalling.

Chloride Attack- This happens in constructions that are exposed to seawater. Chloride attack will induce corrosion to the steel reinforcement, resulting in spalling concrete.

Rough Finishes- A structure with a rough surface finish tends to gather more water on the surface than a building with a smooth surface finish. The rough-finished structure will enhance water seepage and may promote spalling.

The weakly linked concrete blocks may be carefully removed. In most cases, an additional two inches of concrete surround the afflicted region is removed for increased safety. To boost safety even further, sounding devices may be utilised to detect any irregularity in the proximity of the afflicted region caused by spalling. Any area of concern can also be addressed to avoid potential incidents. To eliminate any rust in the steel, wipe the reinforcement with a wire brush. The exposed surfaces must be cleaned with compressed air, and the reinforcements must be coated with an anti-rust polymer or paint. To guarantee adhesion, the existing concrete surface can be roughened to provide enough teeth for good bonding, or bonding chemicals might be utilised. Normal concrete or polymer-based concrete must be used to fill the damaged area. It is critical to ensure that the thermal expansion coefficients of the old concrete and the new filler material are the same. This will eliminate any inconsistencies caused by uneven heating or cooling. To avoid water collection on the surface, the surface should be polished smoothly. Water resistant paints must be applied to the surface to prevent water seepage.

Steel Structures components are usually constructed offsite, whereas reinforced concrete components are mostly cast-in-place. In this circumstance, steel structure has a significant benefit over reinforced concrete because multi-steel elements may be manufactured concurrently, whereas reinforced concrete components are cast step by step, part by part, one at a time, with a 28-day gap (curing) between them. Furthermore, because steel structures are generally lightweight, constructions with steel frames, particularly steel structure buildings, require smaller foundations than reinforced concrete structures. When changes are required, simply removing a steel structural part is far more feasible than dismantling a large reinforced concrete member (Shahrubudin et al., 2019).

Recycling accounts for up to 90% of all Steel Structures on the market today. Steel may be recycled indefinitely without losing strength. The steel industry has kept greenhouse gas emissions below acceptable production limits and is continually improving. Concrete elements are naturally occurring in our surroundings, which means they are not damaging to our ecosystem (Wan  et al., 2018).

Inspection of Steel Reinforcement Receiving, Fabrication, and Installation

Structural steel is extremely malleable and can be molded into any shape without losing its characteristics. It is observed that since it is malleable it can be transformed into sheets or wires. It is observed that it can survive a long span of time. External stresses such as earthquakes, thunderstorms, and cyclones can be reduced by structural steel constructions. If the structure is properly maintained, a well-built steel structure can survive up to 30 years.

At extreme temps, it is observed that steel tends to lose its identity. Steel creation is prone to buckling which results in the rise of length and column. It is observed that when the temperature fluctuates, steel quickly expands, thereby making the worst effect on the total structure (Ghareeb & Farhat, 2018).

It is fairly common in the design-bid-build sector to utilize what is known as prescriptive requirements. If one were to look at a typical highway building contract, he would find the owner directing the contractor on what equipment to use and how to utilize it. Prescriptive specifications are recipes: do this, then this, then this, and so on. If one accomplishes all of those things, he knows that whatever the outcome is, people will accept it. That can be an effective method of specifying work on a design-bid-build project. It's been around for ages. However, it does not work well in the design-build process, since you are unsure exactly what you will receive (Kumar and Gill, 2018)

Standard standards are the types of specifications that may be more appropriate for design-build projects. These requirements are not instructions. They do not instruct the contractor on how to do the task. What they tell the contractor is what the customer wants (Elias & Stathopoulos, 2019).

A standard specification, for example, would inform the contractor exactly what size motor is required to power the vacuum cleaner. A performance specification, on the other hand, would inform them what type of suction is wanted at the other end. The design-builder then decides how to size the motor to fulfill the performance requirements (Zhang et al., 2020).

When the two requirements are compared, it is discovered that the standard specification is more suited for steelworks. The reasons behind that are:

Prescriptive specifications include detailed information and directions, whereas standard specifications include intended outcomes. Prescriptive requirements limit the flexibility of the supplier or contractor, whereas standard standards do. The expenses of prescriptive standards are more foreseeable and fixed, whereas standard specifications allow for budget improvements and cost reductions. Contractors must only follow the prescriptive requirements, but standard specifications allow them to be more creative (Cascone, 2019).

References

Cascone, S. (2019). Green roof design: State of the art on technology and materials. Sustainability, 11(11), 3020.

Elias, C. N., & Stathopoulos, V. N. (2019). A comprehensive review of recent advances in materials aspects of phase change materials in thermal energy storage. Energy Procedia, 161, 385-394.

Ghareeb, N., & Farhat, M. (2018). Smart materials and structures: State of the art and applications. Nano Res. Appl, 4, 1-5.

Huang, J., Meng, H., Cheng, X., Pan, G., Cai, X., & Liu, J. (2020). IOP conference series: materials science and engineering. SYNTHESIS, 12090, 0.

Kumar, K., Gill, R. S., & Batra, U. (2018). Challenges and opportunities for biodegradable magnesium alloy implants. Materials technology, 33(2), 153-172.

Lanko, A., Vatin, N., & Kaklauskas, A. (2018). Application of RFID combined with blockchain technology in logistics of construction materials. In Matec Web of conferences (Vol. 170, p. 03032). EDP Sciences.

Mahajan, A., & Sidhu, S. S. (2018). Surface modification of metallic biomaterials for enhanced functionality: a review. Materials technology, 33(2), 93-105.

Shahrubudin, N., Lee, T. C., & Ramlan, R. (2019). An overview on 3D printing technology: Technological, materials, and applications. Procedia Manufacturing, 35, 1286-1296.

Wan, C., Chen, G., Fu, Y., Wang, M., Matsuhisa, N., Pan, S., ... & Chen, X. (2018). An artificial sensory neuron with tactile perceptual learning. Advanced Materials, 30(30), 1801291.

Wang, F., Wang, K., Zheng, B., Dong, X., Mei, X., Lv, J., ... & Wang, W. (2018). Laser-induced graphene: preparation, functionalization and applications. Materials technology, 33(5), 340-356.

Yang, Y., Song, X., Li, X., Chen, Z., Zhou, C., Zhou, Q., & Chen, Y. (2018). Recent progress in biomimetic additive manufacturing technology: from materials to functional structures. Advanced Materials, 30(36), 1706539.

Zhang, Z., Wang, Z., Shi, T., Bi, C., Rao, F., Cai, Y., ... & Zhou, P. (2020). Memory materials and devices: From concept to application. InfoMat, 2(2), 261-290.