Influence of high water contents on pavement layers stiffness caused by flooding

Moisture inside the construction of road pavements is the problem for road engineers all around the world. This issue is mentioned in many European or the US papers and studies, but still it needs to be developed. From the road engineers’ point of view, very important for solving above problems are the studies on the influence of water and moisture inside the construction of road pavement during deflection measurements using Falling Weight Deflectometer (FWD). The paper raises this issue by showing a short review of Polish and foreign literature and presenting the first step of research work at the test site on Voivodeship Road 933 in Poland

A Comparison of Nondestructive Testing Backcalculation Techniques for Rigid and Flexible Pavements

In designing new pavements, engineers rely on many different measures to characterize the average traffic, climate and soil conditions of the region. Of those, soil conditions are the most elusive, but are also the most crucial for designing a pavement of proper thickness and stiffness. This problem is compounded when the design is for an overlay instead of a new pavement. For overlay designs, engineers require a quantitative characterization of the strength of the existing pavement as well as the underlying soil. Especially for new Mechanistic-Empirical design procedures, direct measures and/or estimates of pavement stiffness are essential inputs. A variety of methods exist for measuring the appropriate strength properties for soil, concrete and asphalt. The most traditional method - regardless of the material - is to retrieve a sample of the material from the field and use laboratory tests to determine the strength of the material, which is then considered representative for other materials near the location from which the sample was taken. The problem with this approach is that, in the field, construction materials experience a confining pressure from the other materials that surround them; even when carefully removed, the strength properties measured in the laboratory are not truly representative of the strength of the materials in the field. Nondestructive testing (NDT) refers to a collection of methods that are used to estimate material properties without removing or otherwise damaging the material. Generally, NDT is faster, cheaper and less intrusive to the traveling public. Two NDT methods, the falling weight deflectometer (FWD) and the spectral analysis of surface waves (SASW), have both become popular for their ability to estimate in-situ (in-place) stiffness properties of pavement materials. Each method measures a different local response (i.e. deflection or wave propagation) caused by a specific load. The measurement of the local response is then used to backcalculate the strength property that is desired. The appropriate backcalculation technique is different for each test, and for each test the appropriate technique varies according to the type of material on which the test is being performed and for which stiffness is sought. This study proposes to assess the validity of several backcalculation procedures associated with these two NDT methods and to compare their relative appropriateness in backcalculating pavement stiffness

A Study Of The Strength Of Pervious Pavement Systems

This thesis presents a study on the strength properties of the different pervious pavement systems installed at the Stormwater Management Academy field laboratory at University of Central Florida (UCF), Orlando. The strength tests were performed both in the laboratory and in the field. Laboratory testing was conducted to determine the compressive strength and flexural strength of the various pavement surfaces. Evaluation of field pavement performance was performed by comparing the deflection basins using the Falling Weight Deflectometer test on pervious concrete and porous asphalt with conventional impervious concrete and asphalt pavements of similar layer profile and thickness, respectively. From literature and previous work at the academy, it is evident that pervious pavements should not be used to withstand heavy traffic loading. They are mostly used in low traffic volume areas such as parking lots, driveways, walkways and some sub-divisional roads. This research studied the compressive strength and flexural moduli. Also it investigated the relationship between the compressive strength and void ratio, unit weight and volume by carrying out laboratory testing of different pervious pavements such as pervious concrete, porous asphalt, recycled rubber tires, recycled glass and porous aggregate. Different sizes of cylinders and beams were cast in place molds for these laboratory tests. Furthermore, the in-situ resilient moduli of the twenty four pavement sections in our research driveway were back calculated with Modulus 6.0 (Liu, et al., 2001) computer program. The calculated deflection basins were compared to the results obtained from a well known computer program called KENPAVE (Huang, 2004). The design of the requisite pavement layer thickness design was performed by doing hand calculations using American Association of State Highway Transportation Officials (AASHTO) method for flexible and rigid pavements and utilizing a Texas Transportation Institute (TTI) computer software known as FPS 19W (Liu, et al., 2006). The structural number for flexible pavements were calculated and tabulated for two different reliability levels (90% and 95%). Traffic loading was estimated in the absence of actual traffic count measurement devices at the field test site. Based on the laboratory testing, the maximum compressive strength of the cored pervious concrete was about 1730 psi. Backcalculated pervious concrete and porous asphalt moduli values were within the specified range discussed in literature. The in-situ modulus of elasticity range for pervious concrete is found to be 740 - 1350 ksi, for porous asphalt 300 - 1100 ksi, for permeable pavers 45 - 320 ksi, for recycled rubber tire 20 - 230 ksi, recycled glass pavement 850 ksi and porous aggregate 150 ksi. For low volume traffic loading, the minimum layer thickness was calculated for rigid pavements and it is presented in this study. In conclusion, this research summarizes the result of laboratory and field testing performed at the University of Central Florida Stormwater Management Academy Research laboratory to determine the strength related properties of pervious pavement systems