Combined effect of Polypropylene fibers and Silica Fume to improve the durability of concrete with natural Pozzolans blended cement

doi:10.1016/j.conbuildmat.2015.08.050

Construction and Building Materials

Volume 96, 15 October 2015, Pages 556-566

https://doi.org/10.1016/j.conbuildmat.2015.08.050 Get rights and content

Highlights

•
Durability parameters of Natural Pozzolan Cement concrete (NPC) were studied.
•
Silica Fume (SF) and Polypropylene short fibers (PPF) were used to improve durability.
•
Short fibers reduced early age cracking and permeability although increased shrinkage.
•
Against expected, SF enlarged shrinkage, cracking, permeability and carbonation.
•
Combined SF and PPF reduced shrinkage, cracking, permeability and carbonation.

Abstract

Early age shrinkage and cracking, water permeability and carbonation depth of concretes with natural Pozzolans blended cement (NPC) were investigated in order to assess the combined effect of Polypropylene short fibers (PPF) and Silica Fume (SF) on some durability parameters.

The addition of 10% of SF increased compressive strength, shrinkage and cracking, permeability and carbonation depth. But, the combination of 10% SF and 0.07% PPF volumetric fraction mitigated early age cracking and significantly reduced water permeability and carbonation depth.

The use of PPF in NPC concrete combined with SF can be recommended to reduce long-term impact of early age cracking, and enhance durability. However, cement should not be reduced when SF is added to mixtures without PPF, because lower CaO reserves may affect final pH, leading to concretes more sensible to carbonation.

Introduction

Natural Pozzolans Cements (NPC) are used in concretes exposed to aggressive chemical conditions, due to their improved chemical resistance resulting from its pozzolanic capacity [1], [2]. Pozzolanity refers to the chemical ability of silicate based fine materials to produce hydrated calcium silicates, through a reaction with Portlandite, which are more stable in time and with smaller CaO:SiO₂ molar ratio than those formed on the hydration of tri-calcium and bi-calcium silicates [3]. NPC also improves sulfate resistance, reduce water permeability and saline moist diffusion [2], [4]. NPC produce less hydration heat than conventional Portland Cement (PC), reducing the risk of early age micro-cracking due to autogenous shrinkage [5], [6].

However, as any other concrete, NPC concretes are prone to early age cracking due to drying shrinkage, which can compromise durability, as far as the material resistance to external attacks depends both on intrinsic permeability and cracking pattern, shape and size. The early cracking and capillary network become the first gateway to external agents that may reduce the lifespan of concretes [7], [8], [9], [10]. Permeability is a key point in concrete durability, as it conditions carbonation, chloride and sulfate attack [2], [9], [11]. In order to study the cracking patter, the cracking area and length of cracks of the concrete mixtures with SF, PPF and combined SF–PPF have been reported in concrete slabs submitted to double-restrained slab’s displacement during early age (24 h) [12].

During the first hours after mixing, the tensile strength of young concrete is very low and it is very sensitive to internal tensions due to drying shrinkage. If severe external conditions occur during setting, a fast water migration and a deficient hydration of the cement grains in the external layer of concrete would happen [13], leading to early age cracking [14], [15]. Cracking would affect permeability, diffusion, and, as a consequence, the lifespan expectations of concrete members [5], [6].

This paper reports a study of the effect of Polypropylene fibers (PPF) and Silica Fume (SF) on durability related parameters of NPC concretes. These additions are used simultaneously in the concrete mixtures to improve concrete durability, through the reduction of both the porous network and the size and amount of early age cracking.

In a previous paper, the effect of PPF on NPC concretes on durability parameters was assessed [16].

Silica Fume (SF) is a well-known addition in concretes due to its small size (0.15 μm) and its pozzolanic activity [17], [18], [19], [20], [21], [22]. SF improves mechanical performance (mainly compressive strength), reduces permeability (due to its small and spherical shape acts as filler) and increases adherence between aggregates and matrix in concretes [23]. Moreover, the addition of SF can also reduce the capillary network of concrete. However, SF pozzolanic reaction with Portlandite decreases pH of the hardened concrete [18], [19].

Short fibers of different raw materials are effective on crack growth control due to early age drying shrinkage on the exposed concrete surface [6], [14]. The length, diameter and geometry of fibers modifies their effectiveness [6]. The inclusion of fibers may also produce shear stresses due to the different mechanical stiffness of fiber and young concrete [24]. Fiber length influences stress intensity and modifies the time when maximum stress values occur. Fiber volumetric fractions (VF) of 0.05–0.1% can reduce early age cracking risk, although there is not a lineal relation between fiber VF and cracking control ability [24].

The addition of PPF in concrete reduces early age cracking because they restrained the volumetric displacements in restrain members by bridging and sewing the fine cracks [16], [25], [26], [27]. Some authors also reported a reduction of water permeability, sorptivity and carbonation of fly ash concretes reinforced with PPF [25]. Larger amounts of PPF (1–2%) could also improve mechanical behavior [28], [29].

Combined PPF and SF have been used to improve some conventional concrete properties in bridge overlays to obtain concretes with low permeability and low chloride diffusion [23], [30] and larger impact resistance of concretes [31].

Section snippets

Materials

The following materials were used on the concrete mixtures studied:

•
CEM II/B-P 32.5 R Portland cement blended with a 18% of Natural volcanic Pozzolans was used, designated according to UNE-EN 197-1:2000 [32]. The bulk oxide chemical composition of the Natural Pozzolan and the Natural Pozzolan Cement (NPC) is described in Table 1.
•
Aggregates: Coarse aggregates 10–20 mm, 5–10 mm and 0–5 mm coarse sand from crushed clinkstone were used. The reference mixture has also natural fine sand from Sahara dunes

Fresh concrete workability

Table 4 shows that the additions, both SF and PPF, reduced concrete workability. This effect was especially remarkable in the SFPPFC compositions, where both additions were combined. The use of a HRWRA mitigated this effect and w/c ratio remained constant [30]. According to some Refs. [16], [30], the fiber shape and its low deformability produce this effect. Moreover, there is a risk of balling-up among fibers, enlarged by the pointed shape of the coarse aggregate [16].

Early age shrinkage and cracking

Fig. 3 relates the free

Conclusions

This paper presents a study on the influence of Polypropylene fiber (PPF) on Natural Pozzolan Cement (NPC) concretes early age and durability performance with and without Silica Fume (SF). The main conclusions, according to the experimental results, are summarized next:

•
The use of PPF slightly reduced density, US Modulus and compressive strength; increased early age drying shrinkage, controlled cracking, reduced permeability and natural carbonation depth.
•
The use of SF increased compressive

Acknowledgements

The authors acknowledge the technical support provided by the University of Las Palmas and the Polytechnic University of Madrid, and the grant awarded by the Government of Canary Islands. They also thank Doris Calderín, David Gonzalez Amago of Grace Construction Materials and Arican S.A for the supply of materials used in the study and to Readymix Asland S.A for the physical–chemical study of the coarse aggregate.

References (38)

K. Sisomphon
Carbonation rates of concretes containing high volume of pozzolanic materials
Cem. Concr. Res.
(2007)
R.E. Rodríguez-Camacho
Importance of using the natural pozzolans on concrete durability
Cem. Concr. Res.
(2002)
E. Roziere et al.
A performance based approach for durability of concrete exposed to carbonation
Constr. Build. Mater.
(2009)
E. Holt et al.
Cracking risks associated with early age shrinkage
Cem. Concr. Compos.
(2004)
N. Banthia et al.
Influence of polypropylene fiber geometry on plastic shrinkage cracking in concrete
Cem. Concr. Res.
(2006)
K. Wang et al.
Permeability study of cracked concrete
Cem. Concr. Res.
(1997)
I. Monteiro et al.
Statistical analysis of the carbonation coefficient in open air concrete structure
Constr. Build. Mater.
(2012)
A. Younsi et al.
Accelerated carbonation of concrete with high content of mineral additions: effects of interactions between hydration and drying
Cem. Concr. Res.
(2013)
G. Barluenga et al.
Cracking control of concretes modified with AR-glass fibers at early age. Experimental results on standard concrete and SCC
Cem. Concr. Res.
(2007)
N. Flores Medina et al.
Enhancement of durability of concrete composites containing natural pozzolans blended cement through the use of polypropylene fibers
Composites: Part B
(2014)

R. Duval et al.

Influence of silica fume on the workability and the compressive strength of high-performance concretes

Cem. Concr. Res.

(1998)

A.M. Boddy et al.

The effect of the silica content of silica fume on its ability to control alkali-silica reaction

Cem. Concr. Res.

(2003)

Andrew J. Maas et al.

Alkali silica reactivity of agglomerated silica fume

Cem. Concr. Res.

(2007)

B.W. Langan et al.

Effect of silica fume and fly ash on heat of hydration of Portland cement

Cem. Concr. Res.

(2002)

G. Barluenga

Fiber-matrix interaction at early ages of concrete with short fibers

Cem. Concr. Res.

(2010)

O. Karahan et al.

The durability properties of polypropylene fiber reinforced fly ash concrete

Mater. Des.

(2011)

M.D. Lepech et al.

Water permeability of engineered cementitious composites

Cem. Concr. Compos.

(2009)

M.C. Nataraja et al.

Reproportioning of steel fiber reinforced concrete mixes and their impact resistance

Cem. Concr. Res.

(2005)

P. Zhang et al.

Effect of polypropylene fiber on durability of concrete composite containing fly ash and silica fume

Composites: Part B

(2013)

Cited by (72)

Effects of alkali equivalent and polypropylene fibres on performance of alkali-activated municipal waste incineration bottom ash-slag mortar
2024, Journal of Building Engineering
Slag demonstrate significant potential as an important cementitious material for alkali-activated systems; however, the increase in alkali-activated materials has resulted in a short supply of slag. Therefore, other industrial wastes must be identified urgently to replace slag as an alkali-activated material while considering the alkali equivalent (AE) as an important factor affecting alkali-activated materials and the modification of polypropylene fibre (PPF). Effect. In this study, the effects of the AE and PPF length on the fluidity, consistency, compressive strength, and flexural strength of municipal waste incineration bottom ash-slag mortar are investigated by partially replacing slag with bottom ash (BA) derived from waste incineration as an alkali-activated material. The mechanism is elucidated via X-ray diffraction analysis and scanning electron microscopy. Finally, studies were conducted on the freeze-thaw resistance and dry shrinkage of alkali-activated bottom ash-slag mortar (AABA-SM). The results show that the performance of an AABA-SM can be modified and enhanced by controlling the AE size and the PPF length. Consistency of AABA-SM increased with the AE. The fluidity and mechanical strength of the AABA-SM enhanced significantly when the AE is 6.5%. PPF length of 12 mm were more significant in increasing the flexural strength of AABA-SM. This is attributed to the denser microstructure formed by the appropriate AE and the superior reinforcing effect of the well-coated 12 mm PPFs.In particular, at an AE of 6.5% and a PPF length of 12 mm, the AABA-SM shows a similar change in terms of dry shrinkage as natural mortar and is better resistant to freezing and thawing. This research provides theoretical support to improve the performance of AABA-SM, enhance the utilization of BA, and reduce environmental pollution.
Influence of waste tire rubber powder, polypropylene fiber and their binary blends on mitigating alkali-silica reaction
2023, Journal of Building Engineering
This work aims to investigate the inhibitory effect and inhibitory mechanism of waste tire rubber powder (abbreviated as WRP) and polypropylene fiber (PPF), and their binary blends on mitigating the alkali-silica reaction (ASR). To achieve this, mortar bars containing either WRP, PPF, or WRP + PPF were prepared for the accelerated mortar bar test (AMBT). The mechanism of ASR inhibition was illustrated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray computed micro-tomography (X-ray CT). The results indicated that the combination of WRP and PPF showed excellent synergistic effect on improving the compressive strength of the mortar cubes. In addition, WRP could effectively alleviate ASR, but the effect depended on the particle size of WRP, with the inhibition effect of 120 mesh WRP being the best. The addition of WRP + PPF exhibited an excellent synergistic effect on the inhibition of ASR expansion, and 120 mesh WRP and PPF with a length of 9 mm and a dosage of 0.8 kg/mm³ showed the best inhibition effect when they were incorporated together. Moreover, the inhibition mechanism of WRP and PPF on ASR was physical effect: WRP consumed the swelling energy generated by water absorption of the gel through deformation, and PPF applied its own bridging effect to suppress crack propagation. Finally, the analysis of the X-ray CT scanning results showed that adding WRP and PPF to the slurry increased the porosity. With the progress of ASR, the gel filled the pores and decreased the expansion. This further revealed more about how WRP and PPF could work together to reduce the damage caused by ASR effectively.
Effects of silica fume type and cementitious material content on the adiabatic temperature rise behavior of LHP cement concrete
2022, Construction and Building Materials
Citation Excerpt :
Meanwhile, silica fume has been proved to further enhance the LHP cement concrete’s early strength [41–42] and improve the concrete structure’s durability [43–44]. Numerous studies have indicated that the performance of concrete is improved significantly by adding silica fume for two reasons: firstly, large surfaced-silica fume is able to quickly work in the pozzolanic reaction and accelerate cement hydration [45–48], and secondly, the pozzolanic reaction of silica fume produces less heat than the process of cement hydration [39–40]. To date, many researchers have explored the hydration heat features of LHP cement [24,28,31,49–50], the performance of silica fume in reducing temperature rises [37–40] and improving the early strength of concrete [41–42,51], and the influence of cementitious material content on the ordinary cement concrete’s adiabatic temperature rise [23,52–54].
In mass concrete, low-heat Portland (LHP) cement is widely used, which calls for a systematic study of LHP cement concrete’s adiabatic temperature rise behaviors to improve temperature control in the early stages of concrete. Herein, the impacts of two kinds of silica fume (purity: 94.97 % and 97.28 %) and three cementitious material contents (445, 475, and 500 kg/m³) on the adiabatic temperature rise and other thermal and mechanical performances of LHP cement concrete were investigated. The correlation between experimental parameters and LHP cement concrete’s adiabatic temperature rise was quantified, and a corresponding model suitable for this type of concrete was obtained. The results illustrated that silica fume type had a limited influence on the LHP cement concrete’s adiabatic temperature rise performance, with a maximum difference of only 1.88 %. By comparison, the effects of cementitious material content were more significant. When the cementitious material content was decreased from 500 kg/m³ to 445 kg/m³, the concrete’s final temperature could be reduced by 10.95 %. In addition, while the effects of silica fume type and cementitious material content on the thermal and mechanical properties of LHP cement concrete were found to be limited, the addition of high purity silica fume caused a more significant enhancement in the mechanical performance of LHP cement concrete. Compared with concrete containing 500 kg/m³ cementitious material, the thermal conductivity and thermal diffusivity of concrete of 445 kg/m³ were shown to increase by 12.53 % and 7.92 %, respectively. Moreover, the composite exponential adiabatic temperature rise model achieved higher accuracy than the hyperbolic model and was found reliable to be adopted to predict LHP cement concrete’s adiabatic temperature rise.
Constitutive model of polypropylene-fiber-fabric-reinforced concrete under uniaxial compression and index conversion of mechanical properties
2022, Construction and Building Materials
Polypropylene fiber (PPF) is often added to improve the mechanical properties of concrete in engineering applications. As a material used extensively in the textile industry, a huge amount of discarded polypropylene fabrics (PPFF) are produced each year. This study used the waste PPFF as the research object to investigate the feasibility of replacing PPF as concrete admixture on the basis of the concept of green environmental protection. The mechanical properties of polypropylene fiber fabric-reinforced concrete (PPFFRC) with five different fabric contents of 0–1.5 kg/m³ under three different curing ages of 14–60 days were tested. Results show that the dosage of 0.9 kg/m³ PPFF is the best. Compared with the polypropylene fiber reinforced concrete with the same dosage at the age of 60 days, the compressive strength increased from 35.83 MPa to 42.83 MPa, the flexural strength increased from 5.99 MPa to 6.344 MPa, and the splitting strength decreased slightly from 2.70 MPa to 2.57 MPa. A uniaxial compression constitutive model of PPFFRC with different fabric contents at different curing ages was established on the basis of the uniaxial compression constitutive model of concrete proposed by Hogenestand and Zhenhai Guo. The correlation coefficient in the constitutive model was determined by using an improved differential evolution algorithm. The conversion relationships between compressive-flexural strength, compressive-splitting strength, and compressive strength-elastic modulus of PPFFRC were constructed. Results show that the waste PPFF has broad application prospect in green concrete and can replace PPF in concrete to some extent.
Influence of natural zeolite on fresh properties, compressive strength, flexural strength, abrasion resistance, Cantabro-loss and microstructure of self-consolidating concrete
2022, Construction and Building Materials
This study aimed to evaluate the effect of natural zeolite (NZ) on some fresh and hardened properties of self-consolidating concrete (SCC). For this purpose, eight mixtures containing 0, 5%, 10%, and 15% NZ as partial replacement of portland cement with two water to binder ratios (w/b) were studied. In order to evaluate the mechanical properties of concrete, compressive strength and four-point bending tests were performed at the ages of 7, 28, and 90 days. The abrasion resistance and Cantabro-loss tests were performed according to ASTM C779-A (procedure A-revolving discs) and ASTM C1747, respectively at the ages of 28 and 90 days. The results indicated that the HRWR demand of SCC mixtures increases with NZ content. However, the viscosity and stability of the mixtures were improved by NZ. Overall, the mechanical properties of SCC mixtures were improved by using NZ. The optimum rate of NZ was found to be 10%. Although the reduction of the w/b ratio had a more significant effect on improving the mechanical properties compared to using NZ, the reduction of the w/b ratio along with the partial replacement of cement with NZ enhanced this effect. In addition, regression analysis showed a strong correlation between the results of abrasion resistance and Cantabro-loss tests. The results of SEM analysis showed a significant reduction in the width, length and number of micro-cracks in the bulk binder paste and the ITZ of 10% NZ mixtures compared to the plain portland cement mixtures. High peak intensities of C-S-H gel and low intensities of ettringite were also observed by XRD analysis in the ITZ of NZ- containing concretes due to pozzolanic reaction.
Effects of silica fume on the abrasion resistance of low-heat Portland cement concrete
2022, Construction and Building Materials
Citation Excerpt :
To avoid concrete cracking caused by shrinkage, researchers have explored the influencing factors affecting the autogenous and drying shrinkage of silica fume concrete, such as the sample size and curing method [41] and water–binder ratio [42]. They found that fly ash [40,43] and fibers [44,45] mixed with silica fume concrete can reduce shrinkage and crack development. Thus, fly ash is widely used in flood discharge systems to reduce early cracking.
With the wide application of low-heat Portland (LHP) cement in flood discharge systems, the requirements for the abrasion resistance of LHP cement concrete have gradually increased. In this work, the effects of silica fume type (Si-Ⅰ, Si-Ⅱ) and silica fume content (0%, 3%, and 5%) on the abrasion resistance and other mechanical properties of LHP cement concrete were studied using rotating jet method, and the correlation between the abrasion resistance and other mechanical properties was quantified. The results showed that the silica fume content significantly affected the abrasion resistance of LHP cement concrete. The abrasion resistance of LHP cement concrete increased by 10.0% and 15.8% when the added silica fume content was 3% and 5%, respectively. The type of silica fume also has a certain influence on the abrasion resistance, and the difference in the abrasion resistance of concrete with the same content but different silica fume types was 0.5–7.8%. Further, 5% silica fume addition increased the early-age strength (compressive strength and splitting tensile strength) and elastic modulus by 2.2–16.2% and improved the 90-d axial tensile properties (axial tensile strength and ultimate tensile strain) by 4.3–16.4%. Compared with the compressive strength and the splitting tensile strength, the elastic modulus of LHP cement concrete strongly correlated with its abrasion resistance and thus can be used as a primary parameter to evaluate the abrasion resistance of LHP cement concrete.

View all citing articles on Scopus

View full text

Combined effect of Polypropylene fibers and Silica Fume to improve the durability of concrete with natural Pozzolans blended cement

Highlights

Abstract

Introduction

Section snippets

Materials

Fresh concrete workability

Early age shrinkage and cracking

Conclusions

Acknowledgements

Cem. Concr. Res.

Cem. Concr. Res.

Constr. Build. Mater.

Cem. Concr. Compos.

Cem. Concr. Res.

Cem. Concr. Res.

Constr. Build. Mater.

Cem. Concr. Res.

Cem. Concr. Res.

Composites: Part B

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Mater. Des.

Cem. Concr. Compos.

Cem. Concr. Res.

Composites: Part B