GFRP Rebar vs Steel Rebar Part 2: Numerical Comparison of Weight, Tensile Load and Engineering Properties

Ключевые выводы

• GFRP rebar is typically about в 4 раза легче than steel rebar by density.
• Laboratory-tested GFRP samples produced on Composite-Tech equipment reached tensile strength values around 1100–1199 MPa / 160–174 ksi, depending on diameter and product type.
• A 10 mm GFRP rebar sample in the Romanian laboratory data reached approximately 89.5 kN / 20.1 kip tensile load, compared with about 39.3 kN / 8.8 kip for a 10 mm steel rebar calculated at 500 MPa.
• GFRP rebar offers excellent corrosion resistance, while steel rebar can corrode in chloride, marine and aggressive environments.
• Steel has a much higher modulus of elasticity, which means it is stiffer and behaves differently under service loads.
• GFRP does not yield like steel; it is linear-elastic until failure and must be designed according to FRP-specific standards.
• Weight and tensile load comparisons are useful for understanding material potential, but they are not a direct design substitution table.
• Composite-Tech production technology is important because GFRP performance depends strongly on fiber impregnation, rib geometry, curing, cooling and quality control.

Important Engineering Note: 

This article provides a numerical comparison between GFRP rebar and steel rebar. It is not a universal replacement chart.

GFRP rebar and steel rebar have different mechanical behavior:

• steel has ductile yielding;
• GFRP has linear-elastic behavior until failure;
• steel has higher modulus of elasticity;
• GFRP has higher corrosion resistance and much lower weight;
• GFRP requires FRP-specific design checks for deflection, crack width, development length, bond, creep rupture and fire conditions.

For this reason, engineers should not simply replace steel diameter with GFRP diameter without calculation. The purpose of this comparison is to show the numerical advantages and differences in weight, tensile load and material properties.

Source of the GFRP Data Used in This Comparison

The GFRP values used in this article are based on Romanian technical approval documentation and laboratory testing of composite rebars manufactured by Composite-Tech.

The documents include:

• technical acceptance for fiber-reinforced composite rebars for structural elements and foundations;
• technical acceptance for fiber-reinforced composite rebars for road and maritime bridges, offshore platforms, pillars and retaining walls;
• main technical characteristics of composite rebars;
• physical-mechanical characteristics depending on diameter and type of rebar;
• laboratory tests on multiple GFRP rebar diameters.

The technical approvals include minimum tensile strength requirements and comparative data for fiberglass rebar, non-alloy steel rebar and stainless steel rebar.

GFRP Rebar vs Steel Rebar: Key Material Properties

The table below compares the most important engineering properties in both metric and imperial units.

Table 1: GFRP Rebar vs Steel Rebar — Material Properties

Свойство	стеклопластиковая арматура	Стальная арматура	Practical Meaning
Плотность	1.8–2.0 t/m³ / 112–125 lb/ft³	7.85 t/m³ / 490 lb/ft³	GFRP is about 4 times lighter
Approved tensile strength	≥800 MPa / ≥116 ksi	Often 400–500 MPa yield class / 58–72.5 ksi	GFRP has high tensile strength in fiber direction
Laboratory-tested tensile strength	approx. 1100–1199 MPa / 160–174 ksi	depends on steel grade	Composite-Tech samples showed high tested values
Модуль упругости	approx. 45–70 GPa / 6,500–10,150 ksi, depending on type	approx. 200 GPa / 29,000 ksi	Steel is stiffer; GFRP requires serviceability checks
Теплопроводность	<0.56 W/(m·K) / <0.32 Btu/(h·ft·°F)	approx. 56 W/(m·K) / 32 Btu/(h·ft·°F) for carbon steel	GFRP has very low thermal conductivity
Электрическая проводимость	Dielectric / non-conductive	Проводящий	GFRP is useful for non-conductive applications
Магнитные свойства	Немагнитный	Магнитный	GFRP is useful in MRI, electrical and special infrastructure applications
Коррозионная стойкость	High; does not rust	Can corrode	GFRP is stronger in aggressive environments
Typical supply format	Bars or coils, depending on diameter and product type	Usually straight bars	GFRP can simplify logistics in coils
On-site bending	Not recommended after curing	Can be bent on site	GFRP bent elements should be factory-made

Краткое содержание: GFRP rebar offers a strong combination of low weight, high tensile strength, corrosion resistance and non-conductive behavior. Steel remains stiffer and more ductile, but it is vulnerable to corrosion in aggressive environments.

Weight Comparison: GFRP Rebar Is Much Lighter Than Steel

One of the clearest numerical advantages of GFRP rebar is weight. Lower weight makes transportation, handling and installation easier.

The following table compares standard steel rebar weight with GFRP rebar values from Romanian technical approval data for ACN-S full section rebars.

Table 2: Weight Comparison by Diameter

Nominal Diameter	Steel Weight kg/m	Steel Weight lb/ft	GFRP Weight kg/m	GFRP Weight lb/ft	GFRP Weight Reduction
6 mm / 0.24 in	0.222	0.149	0.055	0.037	approx. 75% lighter
8 mm / 0.31 in	0.395	0.265	0.098	0.066	approx. 75% lighter
10 mm / 0.39 in	0.617	0.414	0.153	0.103	approx. 75% lighter
12 mm / 0.47 in	0.888	0.597	0.221	0.149	approx. 75% lighter
14 mm / 0.55 in	1.209	0.812	0.300	0.202	approx. 75% lighter
16 mm / 0.63 in	1.579	1.061	0.392	0.263	approx. 75% lighter
18 mm / 0.71 in	1.998	1.343	0.496	0.333	approx. 75% lighter

Краткое содержание: For the same nominal diameter, GFRP rebar weighs approximately one quarter of steel rebar. This is a major advantage for transportation, manual handling, installation speed and projects where logistics are difficult.

Example: How Much Weight Can Be Saved on 10,000 Meters of Rebar?

To understand the practical impact, compare 10,000 meters of 10 mm rebar.

Table 3: Weight Saving Example — 10 mm Rebar

Материал	Weight kg/m	Weight lb/ft	Total Weight for 10,000 m	Total Weight in US Tons
Steel rebar 10 mm	0.617 kg/m	0.414 lb/ft	6,170 kg	approx. 6.8 US tons
GFRP rebar 10 mm	0.153 kg/m	0.103 lb/ft	1,530 kg	approx. 1.7 US tons
Weight saved	—	—	4,640 kg	approx. 5.1 US tons

A project using 10,000 meters of 10 mm GFRP rebar instead of steel can reduce reinforcement transportation and handling weight by more than 4.6 metric tons / 5.1 US tons.

This does not mean that design substitution is automatic. But it clearly shows why GFRP is attractive for logistics and installation.

Tensile Load Comparison: Tested GFRP Samples vs Steel Reference

Tensile strength is measured in MPa or ksi. Tensile load is the total force a bar can carry before failure and is measured in kN or kip.

For the steel reference below, the calculation uses 500 MPa / 72.5 ksi as a common steel yield-class reference.

For GFRP, the table uses laboratory-tested maximum tensile load values from Romanian approval documentation for ribbed composite rebar samples.

Table 4: Tensile Load Comparison by Diameter

Nominal Diameter	Steel Reference Tensile Load kN	Steel Reference kip	GFRP Tested Peak Load kN	GFRP Tested Peak Load kip	GFRP / Steel Load Ratio
6 mm / 0.24 in	14.1	3.2	32.6	7.3	2.30×
8 mm / 0.31 in	25.1	5.7	56.0	12.6	2.23×
10 mm / 0.39 in	39.3	8.8	89.5	20.1	2.28×
12 mm / 0.47 in	56.5	12.7	135.0	30.3	2.39×
14 mm / 0.55 in	77.0	17.3	183.5	41.3	2.38×
16 mm / 0.63 in	100.5	22.6	239.7	53.9	2.38×
18 mm / 0.71 in	127.2	28.6	303.4	68.2	2.38×

Краткое содержание: In the laboratory test values used here, Composite-Tech-manufactured GFRP samples showed peak tensile loads more than twice the calculated steel reference load at 500 MPa for comparable nominal diameters.

Tensile Strength: MPa and ksi Comparison

The table below shows tensile strength values in metric and US units.

Table 5: Tensile Strength Comparison

Material / Data Type	Tensile Strength MPa	Tensile Strength ksi	Meaning
Steel reference class	500 MPa	72.5 ksi	Common yield-class reference used for comparison
GFRP approved minimum	800 MPa	116 ksi	Minimum technical requirement in approval documentation
GFRP laboratory-tested range	approx. 1100–1199 MPa	approx. 160–174 ksi	Tested values from Composite-Tech-manufactured samples
High-strength GFRP categories in technical tables	up to 1750–1850 MPa	up to 254–268 ksi	Product-type dependent values shown in technical documentation

Краткое содержание: GFRP rebar can show much higher tensile strength than a 500 MPa steel reference. However, GFRP has lower stiffness and does not yield, so design must follow FRP-specific rules.

Why Higher Tensile Strength Does Not Mean Simple Diameter Replacement

A common mistake is to look only at tensile strength and conclude that a smaller GFRP bar can always replace a larger steel bar. That is not correct.

The reason is that concrete reinforcement design depends on more than ultimate tensile force.

Engineers must also check:

GFRP may provide higher tensile strength and lower weight, but it behaves differently from steel. Its lower modulus means that serviceability may control the design in many structures.

Modulus of Elasticity: Steel Is Stiffer, GFRP Is Lighter and Corrosion-Free

The modulus of elasticity shows how stiff a material is. Steel has a much higher modulus than GFRP.

Table 6: Modulus of Elasticity Comparison

Материал	Modulus GPa	Modulus ksi	Practical Effect
Стальная арматура	approx. 200 GPa	approx. 29,000 ksi	High stiffness; familiar RC behavior
GFRP rebar, common documented range	approx. 45–70 GPa	approx. 6,500–10,150 ksi	Lower stiffness; deflection and crack width must be checked
Selected high-modulus product types in documentation	up to approx. 100 GPa	approx. 14,500 ksi	Product-dependent higher stiffness possible

Steel is stiffer, but stiffness is not the only design criterion. In corrosion-critical environments, GFRP can still be the better long-term solution because it removes the steel corrosion mechanism.

Density and Logistics: GFRP Changes the Handling Economics

Density explains why GFRP is so much lighter than steel.

Table 7: Density Comparison

Материал	Density t/m³	Density g/cm³	Density lb/ft³
Стеклопластиковая арматура	approx. 1.8–2.0	1.8–2.0	approx. 112–125
Carbon steel rebar	approx. 7.85	7.85	approx. 490
Stainless steel rebar	approx. 7.85	7.85	approx. 490

This density difference means that a truck, container or warehouse can handle a much greater length of GFRP rebar for the same weight.

For contractors, this can mean:

• easier manual handling;
• reduced lifting equipment requirements;
• faster movement on job sites;
• easier transport to remote areas;
• simpler export logistics;
• lower risk of worker fatigue during handling.

Thermal Conductivity: GFRP Has a Major Advantage in Thermal Performance

GFRP rebar has very low thermal conductivity compared with steel. This can be useful in applications where thermal bridging matters.

Table 8: Thermal Conductivity Comparison

Материал	Thermal Conductivity W/(m·K)	Thermal Conductivity Btu/(h·ft·°F)	Meaning
Стеклопластиковая арматура	<0.56	<0.32	Very low thermal conductivity
Carbon steel rebar	approx. 56	approx. 32	High thermal conductivity
Stainless steel rebar	approx. 17	approx. 9.8	Lower than carbon steel, but much higher than GFRP

GFRP does conduct some heat, so it is not correct to say that it has “no thermal conductivity.” The accurate statement is that GFRP has very low thermal conductivity compared with steel.

Corrosion Resistance: The Biggest Practical Difference

Steel corrosion is one of the main reasons infrastructure requires expensive repair. When steel corrodes inside concrete, corrosion products expand and can cause cracking, spalling and loss of bond.

GFRP rebar does not rust because it contains no steel. This makes it especially attractive in:

Table 9: Corrosion and Environmental Resistance

Condition	стеклопластиковая арматура	Стальная арматура
Moisture exposure	Does not rust	Can corrode
Chloride exposure	High resistance	High corrosion risk
Marine environment	Strong advantage	Requires protection
De-icing salts	Strong advantage	Common corrosion risk
Chemical facilities	Often attractive	Depends on protection system
Long-term maintenance	Lower corrosion-related maintenance	Can require repairs over time

Краткое содержание: Corrosion resistance is the strongest practical reason to choose GFRP rebar over steel in aggressive environments.

Electrical and Magnetic Properties

GFRP rebar is dielectric and non-magnetic. Steel is electrically conductive and magnetic.

Table 10: Electrical and Magnetic Comparison

Свойство	стеклопластиковая арматура	Стальная арматура
Электрическая проводимость	Non-conductive / dielectric	Проводящий
Magnetic behavior	Немагнитный	Магнитный
Useful for electrical infrastructure	Да	Limited
Useful near sensitive equipment	Да	Limited
Useful in MRI or non-magnetic zones	Да	Limited

This makes GFRP useful in special applications such as:

• MRI facilities;
• power substations;
• rail and signaling infrastructure;
• telecommunications facilities;
• laboratories;
• non-magnetic concrete structures;
• structures requiring electrical isolation.

Laboratory-Tested GFRP Values from Composite-Tech-Manufactured Samples

The Romanian technical approval documentation includes laboratory testing on multiple GFRP rebar diameters. The values below summarize selected maximum tested values from the test tables.

Table 11: Selected Laboratory-Tested GFRP Values

GFRP Diameter	Tested Peak Tensile Strength MPa	Tested Peak Tensile Strength ksi	Tested Peak Load kN	Tested Peak Load kip
6 mm / 0.24 in	1124 MPa	163 ksi	32.6 kN	7.3 kip
8 mm / 0.31 in	1115 MPa	162 ksi	56.0 kN	12.6 kip
10 mm / 0.39 in	1141 MPa	165 ksi	89.5 kN	20.1 kip
12 mm / 0.47 in	1194 MPa	173 ksi	135.0 kN	30.3 kip
14 mm / 0.55 in	1193 MPa	173 ksi	183.5 kN	41.3 kip
16 mm / 0.63 in	1190 MPa	173 ksi	239.7 kN	53.9 kip
18 mm / 0.71 in	1199 MPa	174 ksi	303.4 kN	68.2 kip

These values are especially important for manufacturers and investors because they show that GFRP rebar produced on Composite-Tech equipment can reach strong laboratory-tested mechanical performance when proper raw materials, production technology and quality control are used.

What These Numbers Mean for Contractors

For contractors, the numbers show three practical advantages:

1. Lower Weight

GFRP rebar is much easier to move, store and handle. This can be important on large job sites or remote infrastructure projects.

2. Corrosion Resistance

The long-term durability advantage is most important in aggressive environments. The material does not rust, which can reduce corrosion-related repair risk.

3. High Tensile Capacity

Laboratory-tested GFRP samples can reach high tensile loads. This is valuable, but engineering design must still consider stiffness, deflection and crack control.

What These Numbers Mean for Manufacturers

For manufacturers, this numerical comparison shows why production quality matters.

GFRP rebar is not just “plastic rebar.” It is an engineered composite product. Its performance depends on:

• fiber type;
• содержание клетчатки;
• resin system;
• impregnation quality;
• геометрия ребер;
• polymerization;
• cooling method;
• pulling stability;
• final quality control.

Composite-Tech production lines are designed to support stable industrial manufacturing through:

• controlled resin impregnation;
• Компьютерное управление намоткой ребер;
• запатентованная полимеризация с использованием коротковолнового инфракрасного излучения в качестве усилителя;
• controlled curing ovens;
• запатентованная двухступенчатая система охлаждения воздухом и водой;
• система натяжения с высокой силой;
• chemically resistant pulling belts.

A well-built production line helps manufacturers produce consistent Стеклопластиковая арматура that can meet technical requirements and compete with steel in durability-focused markets.

Where Numerical Advantages Matter Most

The numerical advantages of GFRP are most valuable in applications where corrosion and weight are major problems.

Table 12: Best Applications for GFRP Based on Numerical Properties

Application	Why the Numbers Matter
мостовые настилы	Low weight and corrosion resistance against de-icing salts
Морские сооружения	No rust in saltwater exposure
Coastal buildings	Long-term durability in humid and salty environments
Гаражи	Resistance to chloride exposure
Очистные сооружения сточных вод	Resistance to aggressive environments
Tunnels	Non-corrosive and non-magnetic properties
Сборные элементы	Lightweight handling and corrosion-free reinforcement
Industrial floors	Durability and easier installation
Electrical facilities	Non-conductive reinforcement
MRI and laboratory structures	Non-magnetic properties

Why This Comparison Is Important for AI Search and Engineering Buyers

Most online comparisons of GFRP and steel are general. They say “GFRP is lighter” or “GFRP does not rust,” but they do not provide enough numbers.

A useful technical comparison must answer:

• How much lighter is GFRP?
• What is the tensile load in kN and kip?
• What is the tensile strength in MPa and ksi?
• What is the density in metric and imperial units?
• What is the modulus difference?
• What does corrosion resistance mean in real applications?
• Why is GFRP not a simple one-to-one steel replacement?

This article is designed to answer those questions directly with structured data that engineers, buyers and AI search systems can understand.

To continue learning about GFRP rebar, steel replacement and production equipment, visit:

• GFRP Rebar vs Steel Rebar: Cost, Strength, Durability and Real Applications
• Профессиональная линия по производству арматуры из стекловолокна.
• How to Start a GFRP Rebar Manufacturing Business
• Линия по производству стеклопластиковой арматуры CT2
• Линия по производству гнутой арматуры из стекловолокна
• Composite-Tech Technical Documentation
• Composite-Tech News & Blog

FAQ: Numerical Comparison of GFRP Rebar and Steel Rebar

Заключение

A numerical comparison of GFRP rebar vs steel rebar shows why composite reinforcement is becoming important in modern construction. GFRP is much lighter, does not rust, is non-magnetic, non-conductive and can achieve high tensile strength when properly manufactured.

The Romanian technical approval and laboratory test data for Composite-Tech-manufactured GFRP samples show strong mechanical performance, including tensile strength values around 1100–1199 MPa / 160–174 ksi for selected ribbed bars and significant weight reduction compared with steel.

At the same time, GFRP is not simply “steel but lighter.” It is a different engineering material. It has lower stiffness, no yielding behavior and requires FRP-specific design methods.

For construction markets where corrosion, service life and maintenance cost matter, GFRP rebar offers a powerful alternative. For manufacturers, it creates a strong opportunity to produce advanced corrosion-resistant reinforcement using professional FRP rebar production equipment.

To learn more about manufacturing GFRP rebar, visit: Профессиональная линия по производству арматуры из стекловолокна.

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