Skid resistant surfacings

Nosing lifting at shrinkage crack or transverse joint 

Despite the development of resin mortar technology in recent years such that many of the causes of the earlier failures have now been eliminated, the confidence of the industry has been severely dented and resin nosings are now a rarity in UK bridge construction. 

Some of the earliest major applications of adhesives in civil engineering involved the use of resins for abrasion resistant and non-slip surfaces to heavy duty floors and roads. This was achieved by the use of synthetic anti-skid grits, such as calcined bauxite, set in a resin base. Both epoxy and polyester resins have been used, applied either by trowel or in slurry form by squeegee. Trowelled systems are usually heavily filled mortars with an aggregate resin ratio of the order of 6 1 and as such usually require a priming 

On steel surfaces solvent degreasing and gritblasting is recommended as the surface preparation method, although where this has to be done in the factory prior to delivery, application of an anti-corrosion priming layer is often specified. A primer which is compatible with the surfacing formulation must be used but, even when applied correctly, there is usually some reduction in bond strength. If a primer is used it is recommended that all solvents be 

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Designers may want to use traditional granite setts as a road surface while Road Safety Auditors want adequate skid-resistant surfaces to enable drivers to stop safely. 

ACI 503.3 Standard specifications for producing a skid-resistant surface on concrete by the use of a multi-component epoxy system. 

A skid resistant surface is an essential part of any pavement surface improvement, regardless of the scope of geometric problems or upgrading. Current policy requires that each Federal-aid project, including RRR projects, involving pavement construction shall provide a skid resistant surface. 

The situation is complicated, however, because some of the drag on a skidding tire is due to the elastic hysteresis effect discussed in Section XII-2E. That is, asperities in the road surface produce a traveling depression in the tire with energy loss due to imperfect elasticity of the tire material. In fact, tires made of high-elastic hysteresis material will tend to show superior skid resistance and coefficient of friction. 

Traction zone or actual contact zone This region is the rear part of the contact area, beginning with the end of transition zone. It is the zone where most of the traction or skid resistance is developed. Here, the lubricating water him has been totally or substanhaUy removed, and vertical equilibrium of the tread elements on road surface has been attained. 

FIGURE 33.17 Effect of silica surface area on wet-skid resistance of vulcanizates filled with different fillers. 

Unsecured objects, such as bricks and gas cylinders, near the edges of elevated surfaces, such as catwalks, roof tops, and scaffolding, which may dislodge and fall on workers Debris and weeds that obstruct visibility Install skid-resistant strips and other antiskid devices on slippery surfaces Construct operation pads for mobile facilities and temporary structures Construct loading docks, processing and staging areas, and decontamination pads... 

The friction of road surfaces is often measured with a skid tester developed by the Road Research Laboratory17 and this has also been widely used on other surfaces and floors, including artificial sports surfaces. It is a pendulum device, the movement of which is arrested by the foot of the pendulum skidding on the surface to be measured. The skid resistance indicated can be approximately related to coefficient of friction by ... 

The values shown in the table indicate that the material compacts to the desired level with a 5-ton vibrating compactor. Surface skid resistance of the sections was measured using a California portable skid tester in accordance with California test method 342 D. The skid values are comparable with published values for fresh-open or dense-graded asphaltic concretes. The friction values increased with increasing sulfur concentration. 

Figs. 11 to 13 illustrate the temperature dependence of strain at failure (in bending test), change in surface roughness with additional traffic exposure period, and skid resistance of the asphalt mixtures using powdered rubbers, respectively. The advantages of the asphalt mixtures are improvements in skid resistance and abrasion resistance, a reduction in traffic noise and a prevention effect of freezing. 

The results for surface smoothness, deformation and skid resistance (Figs. 8-10) were also good for both the new and recycled HMA areas, and no difference was seen between these areas. The recycled HMA areas were not inferior to the new HMA area. 

In 1971, a three-quarter mile surface overlay was placed in Oakville, Ontario using thirteen mix formulations. Skid resistance, wear, and permeability have been measured periodically to assess the suitability of sand-asphalt-sulfur mixes as surfacing materials. 

Sand-asphalt-sulfur surface-wearing courses prepared with coarse sands have a sharp, sandpaper-like surface texture. Skid resistance tests carried out up to speeds of 50 mph have given favorable results. The road surface is not susceptible to polishing because as soon as a sand grain is worn away or dislodged, another sharp sand grain is exposed. Fine sands, such as dune sands, are not suitable for riding surfaces because they yield surfaces which are too smooth. 

The noise generated from moving vehicles on open-textured surfaces, similar to PA, has been found to be reduced when compared with conventional surfacing materials of the same macro-texture and skid resistance coefficient. The reduction measured was 3 to 4 dB(A), when the pavement surface was dry, and 7 to 8 dB(A), when the surface was wet (Nelson and Ross 1981). Similar results were also found by the Belgium Road Research Centre (Decoene 1989) and by Phillips et al. (1995). At a later study, resurfacing an old concrete pavement with PA led to wind-normalised reductions in noise exposure of the order of 4.5 to 6 dB(A) L/ io,i8h at villages approximately 0.5 km from the motorway (Baughan et al. 2002). 

Cold asphalts for slurry surfacing are commonly used worldwide for surface maintenance, for surface maintenance prevention and, above all, for the restoration of surface skid resistance of highways, city streets and airport pavements. 

Type 3 slurry surfacing is suitable to provide, in addition, maximum skid resistance and an improved wearing surface. This type of micro-surfacing is appropriate for heavily trafficked pavements and rut filling. 

The main structural function of a pavement is to sustain traffic loads and distribute them to the subgrade. The stresses transferred to the surface of the subgrade should be such as to cause minimal deformation of the subgrade soil layer. Additionally, part of the upper layers of the pavement structure should be almost impervious to water, so that the subgrade, as well as the unbound layers, is protected from the detrimental effect of surface water. Finally, the pavement surface should be skid resistant, resistant to the polishing action of tyres and even. 

Although the concrete layer is more durable than an asphalt layer, it requires frequent joint maintenance and restoration of the skid resistance property of the surface. The frequency of intervention depends on the quality/suitability of the material used and workmanship achieved. 

Joint maintenance, although time consuming, is generally effective restoration of the concrete surface s skid resistance though is a difficult task and needs special consideration and not always as effective. 

Inadequate curing before opening the pavement to traffic may result in concrete with poor skid resistance owing to loss of surface mortar. Areas with heavy traffic or lanes for commercial vehicles are going to suffer first. 

Gravity fill is also used when cracking is random or patterned. The material normally used is gravity polymer covered with hard and durable sand. Epoxy resin-based materials instead of elastomer/plastomer-based materials are preferred when a longer-lasting surface skid resistance is required. However, this method of repair can be very expensive. 

The surface of the concrete slab should have good texture to provide sufficient and lasting skid resistance. Other factors such as noise generation may be of concern. The provision of good texture is obtained by usual techniques such as tining, hessian drag, broomed, exposed aggregate concrete, stamped concrete and so on, the details of which can be found... 

The activities included in the preventive and corrective maintenance are not essentially independent of each other, except perhaps crack filling, and thus they will not be individually mentioned per case. Works for preventive and corrective maintenance include crack filling, pothole filling, patching, surface skid resistance restoration and surface evenness restoration. 

All types of surface distresses occurring in flexible pavements can be classified into four categories cracking, distortion, disintegration and loss of skid resistance. 

Loss of surface skid resistance is a skid hazard associated with smooth and slippery surface, which directly affects traffic safety. Unlike all other surface distresses, a smooth and slippery surface does not affect the structural deterioration of the pavement. 

Slippery surface may result from polishing and abrasion of the surface aggregate or asphalt bleeding. Both factors reduce the macro- and micro-texture of the pavement surface and the surface skid resistance provided. 

In the presence of water, the surface becomes more slippery hence, the pavement s surface becomes more dangerous. An excess amount of water may result in aquaplaning, a situation where skid resistance is eliminated. 

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