Influence of Carbon Fiber on Mechanical Properties of Polymer Modified Concrete under Impact Load

doi:10.16552/j.cnki.issn1001-1625.2026.0170

Abstract

Abstract:

Polymer modified concrete （PMC） has attracted considerable attention in civil and protective engineering because of its improved toughness， crack resistance， and bonding performance compared with ordinary concrete. However， despite these advantages， PMC remains a quasi-brittle material and still exhibits limited resistance to impact and dynamic loading. To further enhance its mechanical performance and energy absorption capacity under extreme loading conditions， carbon fibers， characterized by high strength， high modulus， and excellent crack-bridging capability， were incorporated into PMC. This study aimed to systematically investigate the influence of carbon fiber content on the static and dynamic mechanical behavior of carbon fiber reinforced polymer modified concrete （CFRPMC） and to reveal its strengthening and toughening mechanisms under impact loading. Four groups of specimens containing carbon fiber volume fractions of 0%， 0.1%， 0.2%， and 0.3% were prepared. Static mechanical tests were conducted to determine compressive strength， split tensile strength， and flexural strength. Dynamic compression tests were performed using a split Hopkinson pressure bar （SHPB） system under different impact pressures. Dynamic stress-strain responses， dynamic compressive strength， peak strain， peak toughness， and failure characteristics were analyzed. Furthermore， the influence of carbon fiber content on crack propagation and fragmentation behavior was evaluated through macroscopic failure observations. The experimental results demonstrate that the mechanical performance of CFRPMC exhibits a distinct trend of initial improvement followed by deterioration with increasing carbon fiber content. Under static loading， the optimal fiber content was found to be 0.2% by volume. At this content， the compressive strength， split tensile strength， and flexural strength reach 31.72， 4.66， and 8.96 MPa， respectively， representing increases of 9.0%， 48.9%， and 43.8% compared with the fiber-free PMC. In addition， the split tensile-compressive strength ratio and flexural-compressive strength ratio increase significantly， indicating a substantial reduction in brittleness and a remarkable improvement in toughness. Under impact loading， all specimens exhibit pronounced strain-rate sensitivity. Dynamic compressive strength， dynamic peak strain， and dynamic peak toughness increase continuously with increasing strain rate. Compared with PMC， CFRPMC shows wider stress-strain plateaus around the peak stress， indicating enhanced post-cracking load-carrying capacity and improved deformation resistance. Among all mixtures， the specimen containing 0.2% carbon fiber exhibits the best dynamic performance. At comparable strain rates， its dynamic compressive strength increases by up to 23.5% relative to PMC， while its impact toughness reaches approximately 2.1 times than that of control specimen. The maximum dynamic compressive strength recorded for CFRPMC with 0.2% carbon fiber reaches 60.17 MPa at a strain rate of 133.3 s^-1.Analysis of concrete crushing morphology reveals that carbon fiber can effectively bridge microcracks and delay crack initiation and propagation during impact loading. Consequently， the failure mode gradually transforms from severe brittle pulverization to block-like fragmentation. Fragment-size observations further confirm a reduction in the proportion of fine particles after fiber incorporation， reflecting enhanced energy dissipation capability and improved structural integrity. However， excessive fiber content （0.3%） leads to fiber agglomeration， increases internal defects， and localizes stress concentrations， ultimately reducing both static and dynamic mechanical properties. Overall， the synergistic modification of polymer and carbon fiber significantly enhances the strength， toughness， and impact resistance of concrete. A carbon fiber volume fraction of 0.2% provides the optimal balance between crack-bridging efficiency and fiber dispersion， achieving simultaneous improvements in static strength， dynamic load-bearing capacity， and energy absorption performance. The findings provide valuable theoretical support and practical guidance for the design and application of high-performance impact resistance concrete materials in protective structures， transportation infrastructure， military engineering， and other critical engineering fields.

Key words: carbon fiber, carbon fiber reinforced polymer modified concrete, dynamic compressive strength, dynamic peak strain, dynamic peak toughness, failure morphology

CLC Number:

TU528

LI Mengyang, ZHANG Chao, WANG Zhihang, ZHANG Yue, SONG Xiaobo, BAI Erlei, MA Jianjun. Influence of Carbon Fiber on Mechanical Properties of Polymer Modified Concrete under Impact Load[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(8): 2664-2675.

Figures/Tables 17

Fig.1 Appearance of redispersible latex powder and carbon fiber

Table 1 Main performance indicators of redispersible latex powder

Exterior

Solid content/%

Ash content/%

Bulk density/（g·cm^-3）

Particle

size/μm

Glass transition

temperature/℃

Minimum film forming temperature/℃

White， light white powder

≥

13 ± 2

400~550

1~7

Table 1 Main performance indicators of redispersible latex powder

Exterior

Solid content/%

Ash content/%

Bulk density/（g·cm^-3）

Particle

size/μm

Glass transition

temperature/℃

Minimum film forming temperature/℃

White， light white powder

≥

13 ± 2

400~550

1~7

Table 2 Main performance indicators of carbon fiber

Diameter $/ μ m$	Length/ $m m$	Carbon content/%	Relative density/（g·cm^-3）	Tensile modulus/GPa	Tensile strength/ $G P a$	Elongation at break/%	Resistivity/（Ω·cm）
$7.0 ± 0.2$	6	≥93	1.76	220~240	>3.0	1.25~1.60	1.5×10^-3

Table 2 Main performance indicators of carbon fiber

Diameter $/ μ m$	Length/ $m m$	Carbon content/%	Relative density/（g·cm^-3）	Tensile modulus/GPa	Tensile strength/ $G P a$	Elongation at break/%	Resistivity/（Ω·cm）
$7.0 ± 0.2$	6	≥93	1.76	220~240	>3.0	1.25~1.60	1.5×10^-3

Table 3 Specimen mix proportion

Specimen No.	Mix proportion/（kg·m^-3）
Specimen No.	Carbon fiber	Polymer	Cement	Water	Gravel	Sand	Dispersant	Water reducer	Defoamer	Film-forming aid
PMC	0	24.50	204	100	536	376	0.82	2.45	0.61	1.23
CFRPMC01	0.83	24.50	204	100	536	376	0.82	2.45	0.61	1.23
CFRPMC02	1.66	24.50	204	100	536	376	0.82	2.45	0.61	1.23
CFRPMC03	2.49	24.50	204	100	536	376	0.82	2.45	0.61	1.23

Fig.2 Preparation process of CFRPMC specimen

Fig.3 SHPB test device

Table 4 Static mechanical properties test results of CFRPMC

Specimen No.	Compressive strength/MPa	Split tensile strength/MPa	Flexuralstrength/MPa	Split tensile-compressive strength ratio	Flexural-compressive strength ratio
PMC	29.09	3.13	6.23	0.108	0.214
CFRPMC01	30.77	4.19	8.47	0.132	0.267
CFRPMC02	31.72	4.66	8.96	0.152	0.291
CFRPMC03	28.67	4.19	8.26	0.146	0.288

Fig.4 Static property curves of CFRPMC

Table 5 Impact compression test results

Specimen No.	Strain rate/s^-1	Dynamic compressive strength/MPa	Dynamic peak strain	Dynamic peak toughness/（kJ·m^-3）	Specimen No.	Strain rate/s^-1	Dynamic compressive strength/MPa	Dynamic peak strain	Dynamic peak toughness/（kJ·m^-3）
PMC	44.9	37.95	7.96	0.172	CFRPMC01	48.9	38.40	8.99	0.227
	68.5	43.38	8.86	0.219		70.7	43.71	9.94	0.315
	82.3	45.81	9.59	0.247		89.7	45.73	10.71	0.373
	99.7	47.26	10.23	0.252		108.7	47.82	11.67	0.386
	114.7	48.80	10.63	0.250		116.9	49.26	11.99	0.465
CFRPMC02	52.2	46.88	10.20	0.328	CFRPMC03	50.7	40.85	9.68	0.239
	75.3	51.56	11.47	0.351		64.8	43.92	10.71	0.272
	89.8	53.87	12.32	0.409		87.4	47.58	11.70	0.344
	115.9	58.07	13.19	0.436		104.3	49.70	12.34	0.399
	133.3	60.17	13.52	0.499		129.6	52.96	12.94	0.401

Fig.5 Dynamic stress-strain curves of CFRPMC

Fig.6 Dynamic compression failure modes of CFRPMC

Fig.7 Dynamic compressive strength of CFRPMC

Fig.8 Dynamic peak strain of CFRPMC

Fig.9 Dynamic peak toughness of CFRPMC

Fig.10 Particle size distribution curves of CFRPMC under different impact compression loads

Fig.11 Particle size distribution curves of CFRPMC under 0.25 MPa impact compression loads

Fig.12 SEM images of CFRPMC

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