Mixture Optimization of Concrete Paving Blocks Containing Waste Silt

Most of the waste materials recycled for the production of new construction materials are by-products of various manufacturing processes, such as the aggregate washing process. Recycling such materials is of paramount importance since it could reduce the adverse environmental impacts resulting from landfilling. Various studies have attempted to recycle different types of waste materials and by-products into concrete paving blocks. However, the availability of literature on concrete paving blocks containing waste silt is quite scarce. Thus, the current paper focuses on mix design optimization and production of concrete paving blocks containing high amounts of waste silt resulting from the aggregate production process. Using the mixture Design of Experiments (DOE), 12 sets of concrete paving blocks with different aggregate blends were produced to optimize the mix design. Once the final mix design was achieved, the physical and mechanical properties of the concrete paving blocks were investigated following the EN 1338 standard. Shape and dimension measurements and various tests, including water absorption, tensile splitting strength, abrasion resistance, and slip/skid resistance were conducted on the experimental concrete paving samples. Overall, the produced concrete paving blocks showed promising properties for future applications in pedestrian walking paths.

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.