Elsevier

Construction and Building Materials

Volume 124, 15 October 2016, Pages 312-342
Construction and Building Materials

Experimental application of EPS concrete in the new prototype design of the concrete barrier

https://doi.org/10.1016/j.conbuildmat.2016.07.105Get rights and content

Highlights

  • A new concrete barrier (NCB) is fabricated with a new shape.

  • EPS concrete is applicable in the concrete barrier.

  • The new model absorbs more impact energy using EPS beads.

  • EPS concrete energy dissipation is higher than that of normal concrete.

  • NCB undergoes failure only at the part facing the strike load.

Abstract

A new concrete barrier (NCB) design that separates the opposing lanes in roads was presented and tested experimentally. The proposed design comprises three parts. The expanded polystyrene (EPS) beads were used to cast the outer parts with 15%, 30%, and 45% replacement from coarse aggregate by volume with silica fume substituted with 10% of cement. Four pressures were applied to the concrete barrier models (2.3, 3.2, 4.5, and 5.8 MPa), which are respectively equivalent to four operational speeds of the vehicles (50, 70, 100, and 130 km/h). Results showed that the failure occurred only in the outer part facing the strike force, and the other parts did not fail. The use of EPS beads with percentages of 15% and 30% was to absorb the impact loads in a good way, and these percentages are better than 45%. The results demonstrated little lateral deflection. Moreover, the EPS beads led little strains and facilitated to absorb the impact force. The new prototype of concrete barrier can be functional in roads with good energy dissipation, and it has conformed with the requirements of the crash concrete barrier test.

Introduction

Concrete road barriers are used to divide opposing lanes of all types of highway roads. Concrete barriers are important in preventing vehicles from entering the opposite lane. Serious traffic accidents may occur when a vehicle crosses to the opposite lane; therefore, concrete barriers are necessary to prohibit vehicles from crossing to the opposite lane and to protect drivers from injury or death and prevent vehicle damage. In addition, concrete barriers are used to prevent vehicles from entering dangerous areas, such as roadsides, narrow medians, and bridge barriers [1], [2].

The protection of road users is one of the most important highway transportation problems. Road accidents may cause death because of currently inadequate concrete barriers. Reducing the effect of vehicle collisions with concrete divider barriers can enhance road safety. Newly designed concrete barriers can absorb large amounts of the energy released in collisions and minimize damage to both vehicles and the concrete barriers.

When a vehicle collides with a concrete barrier, the minimization of the continuity of the collision is very necessary. Existing concrete barriers are too solid. Concrete composite materials that are more flexible and elastic than normal reinforced concrete can absorb vehicle impact as well. Several types of concrete barriers vary in shape, height, width, length, and connection design. In addition, many forms of anchor methods have been improved to reduce the lateral deflection of concrete barrier systems [3].

In some cases, improving road protection is necessary to prevent pedestrians and vehicles from traveling to unsafe districts or using destructive methods. Concrete barriers should be designed such that they can absorb as much of the impact load as possible, which is exerted by vehicles that collide with them, and simultaneously preserve their stability [4].

In the last few years, practical observations have shown that the installed systems along Malaysian highways have remained unchanged. Concrete barriers must be easy to install. Moreover, the concrete barrier design permits replacement, exclusion of sections for repair, and emergency openings. In view of these benefits, the use of concrete barriers in high-impact areas has risen in recent years. More importantly, highway roads require concrete barriers [5], [6].

During accidents on Malaysian highways, vehicles are often completely damaged; vehicle drivers usually die or are injured, and concrete barriers are severely damaged. As a consequence, highway traffic is stopped. Road associations in the United States, as well as those in other countries, have estimated that reconstruction costs amount to millions [7], [8].

Impact resistance is critical for evaluating the dynamic performance of concrete barriers during vehicle collision. The use of sustainable or recycled materials to determine the impact performance of barriers has increased in the last five years. Expanded polystyrene (EPS) beads prepared from a mixture of cement, aggregate, and polystyrene beads with additives have helped improved the workability [9] and sustainability of the material used in studies. Wu et al. [10] experimentally tested EPS concrete in terms of splitting failure. In addition, Hu Jun et al. [11] used a split Hopkinson pressure bar (SHPB) to dynamically test EPS concrete using EPS beads with different sizes. EPS concrete was sensitive to the strain rate under the loading conditions. Energy absorption was studied by Hu Zebin et al. [12]. They found that the EPS concrete energy absorption capacity increased and then decreased with the increasing EPS concrete volume fraction; an EPS fraction of 20–30% presented the highest energy absorption capacity. Fan et al. [13] studied the early dynamic effect of early strengthened EPS concrete and compared it with 28-day EPS concrete. The impact mechanics property of EPS concrete increased with duration. Excellent impact toughness resulted from the use of EPS concrete. Ding et al. [14] experimented with early strengthened EPS concrete by using a split Hopkinson pressure bar (SHPB) to determine the dynamic mechanical properties. The extension of the conservation period resulted in an increase in the impact mechanical properties of EPS concrete. Tang et al. [15] used polystyrene aggregate concrete in reinforced concrete beams with glass fiber reinforced polymer (GFRP) to strengthen the flexural capacity of beams. An EPS concrete is used in the production of hollow bricks and blocks [16], [17], [18].

Moreover, rubber concrete composed of recycled tire rubber has been used in some studies. New Jersey-shaped concrete barriers made from rubber concrete materials were tested by Atahan et al. [19]. The results showed that a vehicle’s maximum deceleration forces at the moment of collision decreased when the rubber content was increased, which resulted in reduced damage caused by the accident. Elchalakani [20] experimented with rubberized concrete composed of silica fume (SF), and this composite concrete was implemented in the design of roadside barriers to reduce accidents. With these considerations, studying the use of sustainable materials in concrete, such as expanded polystyrene (EPS) beads, and reducing vehicle impact effects are important components in concrete barrier design.

In this study, a new concrete barrier (NCB) design is introduced; it is used in locations that are deemed to be dangerous areas for vehicles. A new shape with three parts and an interlocking connection between adjacent concrete barriers were used in the new design. The NCB is cast using EPS beads, as one of the composite materials, with other materials. EPS concrete is used in the outer part of the prototype model, whereas normal concrete is used for the middle part. Four concrete barrier models were tested in this study. One model was the control model, using normal concrete in all parts of the model. The three other models used EPS concrete, and they were produced by replacing 15%, 30%, and 45% of the coarse aggregate volume with EPS beads, with cement substituted by 10% SF. This composite concrete was used in the two outer parts, whereas normal concrete was used in the middle part. The four impact velocities for striking each model were 50 km/h, 70 km/h, 100 km/h, and 130 km/h.

Section snippets

New prototype of concrete barriers

Many factors affect the design of concrete barriers used as dividers on roads, including their shape, width, and length; concrete barrier segment connection; and connection of concrete barriers with the ground. The proposed design for the new prototype of concrete road barriers provides more stability, optimal dimensions, sustainability, and new architectural shapes.

Materials

Portland cement type I meeting the BS 8500-1:2006 specifications and a type of supplementary cementitious material called SF were used to complete this study. SF is a very fine material whose particle size distribution may be indeterminate because of agglomeration, and the effective mean of particle size is significantly greater for this material than for materials that are not agglomerated [22]. Adding SF to increase the bonding between EPS beads and the cement paste further increases the

Concrete properties

Table 3 reveals the concrete properties of compressive strength, modulus of elasticity, concrete density, and slump.

Finite element method (FEM) verification

In finite element software modeling, the analysis of engineering problems can be handled through the use of suitable codes or programs. The non-linear explicit dynamic ANSYS 14 finite element software was used for the numerical simulations conducted in this study to verify the experimental work of the new concrete barrier model. A computer simulation of the impact test was performed for the new concrete barrier model, as shown in Fig. 21.

The model meshing of the new concrete barrier design

Conclusions

The experimental study was conducted to test the NCB design. The models were tested using EPS beads by replacing 15%, 30%, and 45% of the coarse aggregate volume, and one model used normal concrete. The EPS concrete was used in the outer parts to reduce the effect of the energy generated from vehicle collision against concrete barriers.

  • 1-

    The reduction in the compressive strength of the concrete occurred in the EPS concrete of 79%, 64%, and 55% of the normal concrete strength for CSE15, CSE30, and

Acknowledgements

The authors would like to acknowledge the Department of Civil and Structural Engineering, Faculty of Engineering and Built Environment, UKM as well as the concrete laboratory for their help in this research. This study is part of a research project financially supported by the Faculty of Engineering and Built Environment, UKM, Malaysia (grant number: FRas/1/2013/TK06/ukm/01/1).

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