bending performance of basalt fiber reinforced cement
TRANSCRIPT
Bending Performance of Basalt Fiber Reinforced Cement
Fanjie Chu1,a, Huawu Liu1,4,b, Zongbin Yang2, Hongming Dai3
1Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Tianjin 300160,
China
2Tianjin Silica Research Institute, Tianjin 300111, China.
3Tianjin Dingshang Technology Limited, Tianjin 300384, China.
4Hunan Textile Research Center, Hunan 414200, China.
[email protected], [email protected]
Keywords: Basalt fiber, Basalt Gridding Cloth, Mortar, Flexural Strength.
Abstract. Basalt fiber is highly active when react with cement, thus was used as a replacement of
steel rebar to enhance the flexural performance of cement mortar. Basalt fiber and its grid fabric
were used in this study. The resulting bending strength revealed that the bending strength of short
fiber and grid fabric reinforced mortar were improved 29.4% and 49.03%, respectively. The
bending strength of mortar reinforced by the combination of short fiber and grid fabric increased up
to 59.57%, which is significant.
Introduction
Cement mortar is the mixture of cement, sand, water and additives and has been widely used in civil
construction[1]. High-performance mortar should have good workability, water retention, toughness,
tensile strength and crack resistance, to meet the requirement of high quality structures. Cement is a
typical capillary porous body. In the early stage of drying, the removal of water results in shrinkage
and cracks. The reinforcing fiber and fabric may reduce the shrinkage and internal checks, thus
improving the mortar tensile strength and toughness [2].
Carbon and aramide fibers are too expensive to be adopted as the reinforcement of cement
mortar. Fiberglass may be quickly corroded in the alkaline environment of cement, thus is forbidden
in cement structures. The ideal cement reinforced fibers should have high active index, stiffer than
cement, high tensile strength, uniform dispersion, and heavy-duty anti-corrosion. So far, only basalt
fiber meets all the stated criteria among all high performance fibers [3, 4].
Therefore, basalt fiber and its grid fabric were used as reinforcing materials for improving the
bending strength of cement specimens. The reinforcing materials were categorized into short basalt
fiber, basalt grid fabric and the mixture of the former two.
Materials and method
Cement PO32.5 was an ordinary Portland cement, provided by Tianjin Cement. Chopped basalt
fiber and grid fabrics were supplied by Sichuan Tuoxin Aerospace Basalt Industrial Limited. Sand
was middle size river sand and the water was obtained from the laboratory tap. The ratio of cement:
sand: water was 2: 3: 1 and basalt fibers added to the five specimen groups were 0 Kg.m-3, 0.5
Kg.m-3, 1.5 Kg.m
-3, 2.5 Kg.m
-3, and 3.5 Kg.m
-3(M0-M4), progressively.
Advanced Materials Research Vols. 332-334 (2011) pp 2142-2145Online available since 2011/Sep/02 at www.scientific.net© (2011) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.332-334.2142
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The cement, sand and reinforcing basalt fiber were poured into a cement mortar mixing
machine. The ingredients were slowly dry-stirred for 1.5 minutes, then fast wet-stirred for 1.5
minutes. The same mixing ratio of cement, sand and basalt materials was applied for fabric
reinforcement. The grid fabrics were laid into the cement mortar matrix, with the weft or warp
direction parallel to the potential load. The reinforcing fabrics were marked as M5, M6, M7 and M8
for the first, second, third and fourth layers, respectively. When the reinforcement was the mixture
of fibers and grid fabrics, the chopped basalt fiber was 2.5 Kg.m-3 and the first, second, third and
fourth fabric layers were labeled as M9, M10, M11 and M12, progressively.
According to standards GB_T50081-2002, sample size was 100mm ×100mm ×400mm. The
specimens were moved out from their molds after 24 hours, sprinkler maintaining for 28 days at
room temperature. A 1000KN hydraulic universal testing machine was used for the bending test [5].
Results and discussion
The effect of fiber mixing ratios on the bending properties of cement mortar. Basalt short
fibers formed a reticular structure inside the samples, which may be pulled out or broken down to
bear the external load and improve the bending strength of the concrete samples [6]. Table1 reveals
that from M0 to M4, with the increase of basalt fiber mass, the bending strength went up firstly and
decreased afterwards. When the mass ratio of the basalt fiber was 1.5 Kg.m-3(M2), the flexural
strength of the mortar reached its maximum 4.67MPa, the relative growth rate increased 26.9%. It
may be concluded that the optimum proportion was in between 1.5 Kg.m-3and 2.5 Kg.m
-3.
Table 1 The effect of fiber mixing ratios on flexural properties of the cement mortar
number enhancement mixing amount failure load flexural strength growth rate
pattern (Kg.m-3) ( KN) ( MPa) (%)
M0 normal mortar 0 12.03 3.61 -
M1 short fiber 0.5 13.10 3.9 8.03
M2 short fiber 1.5 15.55 4.67 29.4
M3 short fiber 2.5 12.6 3.78 4.71
M4 short fiber 3.5 15.25 4.58 26.9
The effect of fabric on flexural properties of the cement mortar. Table 2 shows the
relationship between the flexural strength and the amount of fabric layers. With the increase of the
fabric layers from M5 to M8, the flexural strength went up stably. The maximum bending strength
was found in sample M8, which was 49.03% stronger than the sample without reinforcement. There
was a fabric laid parallel to the neutral plane, when 3 reinforcing fabrics were applied. In theory, the
bending rigidities should be very close when 2 or 3 fabrics were laid in the concrete matrix.
However, the fabric in the neutral plane might be a little apart from the designed position, which led
to a relative large difference in bending rigidities. It can be seen from Table 2 that the bending
strength moved up with the numbers of fabrics applied.
Table 2 The effect of fabric mixing on flexural properties of the cement mortar
Number enhancement layer number mixing amount failure load flexural strength growth rate
pattern (Kg.m-3) ( KN) ( MPa) (%)
M0 normal mortar 0 0 12.03 3.61 --
M5 fabric 1 2.61 13.13 3.94 9.14
M6 fabric 2 4.32 13.35 4.01 11.1
M7 fabric 3 6.48 13.54 4.06 12.47
M8 fabric 4 8.64 17.92 5.38 49.03
Advanced Materials Research Vols. 332-334 2143
The effect of fiber and fabric mixing ratios on flexural properties of the cement mortar.
The reinforcing fibers were 2.5 Kg.M-3 and uniformly distributed for all the samples to eliminate the
influence of fiber weight and position. It may be seen from Table 3 that with the increase of fabric
layers, the failure load and flexural strength went up stably, the maximum value of flexural strength
was 5.76MPa, which was 59.57% stronger than the sample without reinforcement.
Table3 The effect of fiber and fabric mixing ratios on flexural properties of the cement mortar
Number enhancement mixing amount layer number total adding failure load flexural strength growth
pattern (Kg.m-3) amount (Kg.m-3) (KN) (MPa) rate (%)
M0 normal mortar 0 0 0 12.03 3.61 --
M9 short fiber +fabric 2.5 1 4.66 16.50 4.95 37.12
M10 short fiber t+ fabric 2.5 2 6.82 17.81 5.34 47.92
M11 short fiber +fabric 2.5 3 8.98 18.2 5.46 51.25
M12 short fiber +fabric 2.5 4 11.14 19.2 5.76 59.57
M 0 M 1 M 2 M 3 M 4 M 5 M 6 M 7 M 8 M 9 M 1 0 M 1 1 M 1 2
0
2
4
6
Flexural strength (MPa)
S p e c im e n s n u m b e r
Figure 1.Enhance the flexural strength values in different ways
Conclusions
In Figure 1, the comparison sample without reinforcement was labeled M0; the first sample group
was enhanced by different weights of fibers and marked with M1, M2, M3 and M4; the second
sample group was enhanced by different number of fabric layers and marked with M5, M6, M7 and
M8; the third sample group was reinforce by the combination of fiber and fabrics, where the fiber
was 2.5 Kg.M-3 and the layers of fabrics for samples M9, M10, M11 and M12 were 1, 2, 3 and 4,
respectively.
The experimental data of the first group revealed that the bending properties and toughness of
the cement mortars were significantly improved compared with sample M0. In addition, the
bending strength went up with the weight of reinforcing fibers. The peak 4.67MPa was reached
when the weight of basalt fiber was 1.5 Kg.m-3, which was 26.9% stronger than that of sample M0.
The fabrics were evenly laid inside the samples. From the experimental data shown in Table 2,
we may find that the fabrics placed in the neutral plane and compression side did bear much load.
The best position for the reinforcing fabrics should be close to the surface under tension.
Nevertheless, the bending strengths increased with the number of fabrics and the maximum
5.38MPa was reached when 4 grid fabrics evenly distributed in sample M8, which was 49.03%
stronger than the sample without reinforcement.
2144 Advanced Textile Materials
The reinforcements of the third sample group were 2.5 Kg.M-3 short fibers and grid fabrics. As
expected, the maximum strength 5.76MPa was achieved in sample M12 with 4 enhancing fabrics
evenly distributed inside the sample, which was 59.57% stronger than the sample without
reinforcement. From the statement above, we find that all the reinforcements were effective, except
for the fabrics placed in the neutral plane and in the compression side.
References
[1] Z. Wu: Concrete and Cement Products, (1):5-6(1999)
[2] X. Shi: Chemical Industry Press in Beijing, 2007
[3] D. Tamás: Textile Research Journal, 79(7):645-651. (2009)
[4] Z. Zhong and H. Liu: Technical Textiles, (2):33-35. (2008)
[5] B. Jiang and T. Chen: Concrete and Cement Products, (4)50-51. (2008)
[6] D. Zhao and H. Liu: Technical Textiles, (8)39-44. (2010)
Advanced Materials Research Vols. 332-334 2145
Advanced Textile Materials 10.4028/www.scientific.net/AMR.332-334 Bending Performance of Basalt Fiber Reinforced Cement 10.4028/www.scientific.net/AMR.332-334.2142