A Practical Guide to Concrete Pavement Technology for Developing Countries

This guide provides technical information for planning and constructing concrete pavement. Theoretical and practical considerations discussed are comprehensive, interesting, and useful especially for developing economies.

Analysis of the Coupling Effect of Thermal and Traffic Loads on Cement Concrete Pavement with Voids Repaired with Polymer Grout

Under the repeated action of traffic and thermal loads, a cement concrete pavement slab may partially lose contact with its base course, and voids may develop underneath the slab. Such distress will greatly impact the pavement performance. To fill the voids and restore the base support to the slab, the technology of polymer grouting has been increasingly adopted in recent years due to its advantages of quick application and high efficiency. There is, however, a lack of research on the mechanistic responses and performance of such a repaired rigid pavement under coupled influences of thermal and traffic loads. Existing literature has mainly focused on normal cement concrete pavement structures (i.e., without polymer grouted voids). This study intends to fill the research gap by investigating the time-domain characteristics of thermal stress response of a cement concrete pavement with underlying voids filled with polymer grout, along with design traffic loads. The finite element method was adopted with a 3-dimensional nonlinear temperature field within the pavement. A program module was developed in the Abaqus FEA software environment for temperature effect analysis. It was found that under the coupling action of thermal and traffic loads, thermal stress had a greater influence on the critical slab stress at the slab corner than those at other slab locations. Through the comparative analysis before and after polymer grouting repair, the critical tensile stress at the slab corner under the vehicle and thermal loads can be effectively reduced. The polymer performance is stable after three years.

Full-scale Test on Emergency Repair Pavement under Airplane Loading

In order to reveal structural response law of emergency repair pavement under the airplane loading and verify the backfill material and structural applicability, two craters (Crater 1 composed of 2.4 m thick flying objects (FO) + 0.4 m thick graded crushed rocks (GCR) + 0.2 m thick roller compacted concrete + fibre reinforced plastic (FRP) course, and Crater 2 composed of 2.4 m thick FO + 0.6 m thick GCR + FRP course) were backfilled. Static and dynamic loads were applied using two airplanes. Results show that, laying FRP pavement layers reduced the maximum deflection of Crater 2 by 21%. Crater 1 and concrete pavement were both slightly rigid structures with a strong load transfer ability. The dynamic deflection basin curves of Crater 2 could be fit using a Gaussian function; while the curves of Crater 1 and concrete pavement could be fit using a quartic polynomial. Under static loading, the earth pressures of Crater 2 at −0.6 m, −0.4 m, and −0.2 m sites were 4.3, 9, and 9.6 times of those of Crater 1, respectively. At the −0.2 m site, the earth pressure of Crater 1 was 0.11 MPa, while that of Crater 2 reached 1.06 MPa. The research results can guide the rapid quality inspection and optimization design of emergency repair pavement structure and material.

New Long-Life Concrete Pavements in the Czech Republic

A jointed plain concrete pavement represents a reliable, historically proven technical solution for highly loaded roads, highways, airports and other industrial surfaces. Excellent resistance to permanent deformations (rutting) and also durability and maintenance costs play key roles in assessing the economic benefits, rehabilitation plans, traffic closures, consumption and recycling of materials. In the history of concrete pavement construction, slow-to-normal hardening Portland cement was used in Czechoslovakia during the 1970s-1980s. The pavements are being replaced after 40-50 years of service, mostly due to vertical slab displacements due to missing dowel bars. However, pavements built after 1996 used rapid hardening cements, resulting in long-term surface cracking and decreased durability. In order to build durable concrete pavements, slower hardening slag-blended binders were designed and tested in the restrained ring shrinkage test and in isothermal calorimetry. Corresponding concretes were tested mainly for the compressive/tensile strength evolution and deicing salt-frost scaling to meet current specifications. The pilot project was executed on a 14 km highway, where a unique temperature-strain monitoring system was installed to provide long-term data from the concrete pavement. A thermo-mechanical coupled model served for data validation, showing a beneficial role of slower hydration kinetics. Continuous monitoring interim results at 24 months have revealed small curling induced by drying and the overall small differential shrinkage of the slab.

Has Diamond Grinding Been A Cost Effective Pavement Preservation Treatment In Australia?

Australia introduced conventional longitudinal diamond grinding of highway concrete pavements in 2009 with the purchase of two "4‐foot" highway grinding machines by two contractors. The availability of these machines in Australia has enabled contractors to improve ride quality of new pavements, rather than accept a deduction to the tendered rate for the supply and placement of concrete pavement. Grinding of new concrete base is permitted up to an IRI of 3.5 m/km, thereby reducing the need to remove and replace concrete pavement which met the specified thickness, strength and density, but not ride quality. More importantly, with the introduction of the grinding machines, asset managers have the opportunity to use diamond grinding to treat existing concrete pavements that have a rough ride, or when the textured surface no longer meets specified levels for skid resistance. Although the primary use of diamond grinding was to improve ride quality of new and existing concrete pavements, it has also been used to: treat stepping across transverse contraction joints in PCP, improve skid resistance at roundabouts, improve both ride quality and texture for JRCP pavements (greater than 40 years of age) with a thin wearing course and spalling in the asphalt at transverse joints. The above treatments to concrete pavement allow asset preservation and avoid high reconstruction costs. The Austroads concrete pavement design procedure is based on the PCA design method and road smoothness is not a design parameter, unlike the USA approach to concrete pavement design where ride quality is a design input. There is still much work to be done to convince asset managers in Australia that the removal of the high areas of a concrete pavement to smooth the surface, reduces the dynamic wheel loading and minimises accumulated fatigue stress in the concrete. This paper reviews the last 10 years of diamond grinding projects and the success of this pavement preservation treatment for new and existing urban and rural concrete pavements in Australia. Recommendations to reduce the cost of diamond grinding concrete pavements and extend the use of this treatment are also provided.