No description available.

No description available.

This is a bachelor thesis in the course Industrial Automation, PPU301, commissioned by Volvo Construction Equipment in Eskilstuna. This thesis treats how we can increase the effectiveness of production in roadside construction through automation. The report presents different concepts of automation and in the end of the report you can read about the concept I recommend and why. The work has been divided into different stages. In the first stage I have collected information by reading articles and by site visits. The black top process has been identified though a storyboard. The focus is on which machine that would benefit the most from automation. After identifying the process and the customer’s needs, I get a clear view of what the machines should be able to do. After studying both the paver and compactor, I decided to focus on the compactor. There are significant potential for further development of the compactors in regards of automation. I will present a concept of a totally autonomous compactor. The compactor must, among other things, be able to position and identify objects, like machines, workers and other road users. The compactor needs to get a clear signal when the road piece is finished with compaction. The packing operation is automatic controlled depending on the type of mix of asphalt, thickness and speed. There are different solutions to make the compactor autonomous. In the report, I have detailed the different concepts and the sensors needed to realize an autonomous machine.

The Home Committee Report, published in 1985, identified the need for the reinstatement of service trench backfill to be performed to a higher and more reliable standard. This end was perceived as desirable, not only to improve road quality and safety, but also to increase the protection afforded to utility apparatus, thereby reducing the number of excavations required for its repair and replacement. The replacement of existing method specifications with a performance specification, based on the testing of an appropriate property of the reinstated material, is one possible means of improving the quality of reinstatement works. The Clegg meter is finding increasing usage for the purpose of compaction measurement. This device is simple to use and measures the decceleration response of a mass in collision with the ground surface. The decelartaion response is characterised by the Impact Value. The sampled volume is, however, very small in relation to the volume of material compacted and, for full evaluation, each compacted layer must be individually tested prior to the placing of the subsequent layer. The ideal test would be non-intrusive and operable from the final surface of the granular backfill; wave transmission velocity measurements are thus a potential technique. The propagation of sinusoidally excited Rayleigh-type surface waves is identified as the most promising method of measurement for reinstatement backfill quality. Experimental measurements of particle displacement at depth lend credence to the classical assumption that the depth of propagation of Rayleigh-type surface waves is equal to one-half the wavelength (z = γ/2).Included in this thesis is a review of the salient aspects of reinstatement works and a presentation of the necessary theory of wave propagation. The experimental results presented relate to tests on two sand materials compacted using different levels of compactive effort in all above-ground laboratory based trench and also to tests conducted on a crushed limestone aggregate under field conditions. Results from a short programme of field-based case studies are also presented. In addition to the surface wave velocity and Impact Value results, values for dry density and CBR are also presented. The data generally show a good correlation with compactive effort, whether defined simply as the number of passes/layer (N(_p)) or by a new parameter, the ratio of N(_p) to the mean layer thickness (N(_p)/h). Sensitivity analyses indicate that the Impact Value is a more sensitive measure of the degree of compaction than are either the surface wave velocity or the dry density. Conversion of the surface wave velocity results to shear modulus values, using measured density values, gives a sensitivity to compactive effort that is broadly comparable to that of the Impact Value. A novel technique for the analysis of Rayleigh-type surface wave attenuation data is presented. This allows the calculation of the material attenuation coefficient while obviating the need for potentially erroneous estimates as to the state of the attenuation curve, close to the source of vibration, to be made.

No description available.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

The thesis represents an effort to assess the current and future development of expert systems relating to civil engineering problems. It describes the development and evaluation of an Expert System (ESEMPS) that is capable of advising on earth allocation and plant selection for road construction similar to that of an expert in the domain.

Roads constructed on expansive clays may be adversely affected by the behaviour of the clay. Expansive clays suffer volume change due to changes in moisture content which causes heaving, cracking and the break up of the road pavement. Stabilisation of these types of soil is necessary to suppress swelling and increase the strength of the soil and thus partially decrease the thickness of road pavement layers. The use of by-product materials for stabilisation has environmental and economic benefits. Ground granulated blastfurnace slag (GGBS), a by-product material in Egypt, and lime are used in the current work to stabilise samples of a clay soil similar to a typical Egyptian clay soil. This test soil comprises 80% River Aire soil and 20% calcium montmorillonite. The main objectives of this research were to investigate the effect of GGBS, with and without lime, on the engineering behaviour (plasticity characteristics, compaction, unconfined compressive strength (UCS) and swelling potential) of the test soil and to identify the reaction products of the stabilised materials to determine the mechanisms by which changes in engineering properties are obtained. In order to achieve these objectives, extensive laboratory investigations were carried out. Various mixes (up to 10% GGBS by dry weight of the test soil and up to 30% replacement by hydrated lime) were prepared and cured under two representative conditions {20°C with 90-100% relative humidity (CCI) and 35° C with 50-60% relative humidity (CC2)} for up to 12 months. Compaction and plasticity were measured soon after mixing, the swelling potential and UCS were measured after longer curing periods. Four analytical techniques {X ray diffraction, scanning electron microscopy, differential thermal analysis and nuclear magnetic resonance (NMR)} were used to identify the reaction products of the clay fraction of the test soil mixed with various amount of GGBS and lime. This pure clay test soil was used to ease identification of the reaction products. The investigations showed that generally the engineering properties (UCS, swelling, plasticity) improved with the addition of GGBS and with increasing curing period and temperature. The addition of lime resulted in a dramatic improvement within the test ranges covered in the programme. The maximum dry density, MDD, decreased and the optimum moisture content, OMC, increased with increasing GGBS and lime content. The major changes in the UCS and swelling behaviour are due to the formation of new cementitious materials. The analytical investigation confirmed two major reactions when GGBS and lime were added to the pure clay soil, hydration of GGBS activated by lime to produce calcium aluminosilicate hydrate gel (C-A-S-H) and hydrotalcite type phase, and the clay-lime reaction to produce calcium silicate hydrate (C-S-H), (C-A-H) and (C-A-S-H). The NMR test results revealed that the aluminosilicate chain length (EL), the aluminium: silicate (Al/Si) ratio and the amount of Si in the formed C-S-H significantly increased with an increase in the curing temperature and period, which indicates a more stable and well crystalline C-S-H. The results indicate that the use of GGBS alone, or preferably with lime, could have a significant effect on the behaviour of potentially swelling clays. Recommendations for further studies include a study of the effect of cyclic loading on the test soil. Also, site trials should be carried out to assess the suitability of using these materials in the field.

Gypcrete occurs in the western arid and semi-arid regions of South Africa and Namibia. These soils exhibit a complex nature and abnormal behaviour due to their gypsum content and as such they have become more prevalent in research. As these soils are finding more use in industry, a keen understanding of their properties and behaviour is required. Powdery and indurated gyprete samples collected from the Northern Cape (Geelvloer) and Western Cape (Rooiberg and R355) Provinces, are subjected to a series of standard test protocols for road construction materials and then compared to similar studies done on gypcrete both in South Africa and abroad, where gypcrete is researched more extensively and used successfully. The samples collected were dried at 40 °C to prevent phase transitions that will affect the properties of the material. The strength of powdery gypcrete is sensitive to density changes; therefore achieving a high density during compaction is imperative, while the strength of more indurated samples remains unaffected by density. The soaking period before the CBR is also deemed unsuitable for gypcrete as four days results in an overestimation of strength. It is apparent that the properties of gypcrete are affected by several factors, including the formation conditions, type of gypsum, and amount of gypsum, particle size distribution, the size of gypsum particles relative to other particles in the soil and the presence of other salts, all of which affects gypcrete differently making it difficult to form clear trends. The samples are also subject to wetting and drying cycles at 40 °C and 60 °C before the CBR values are determined again, to assess the variation in strength due to mineral alteration. An increase is seen for all samples dried at the higher temperature. This leads to the notion that gypcrete possesses self-stabilising properties, where temperatures in hot areas could dehydrate the gypsum, which will then readily re-absorb atmospheric moisture, leading to the formation of cementing between particles and an increase in strength. The testing served as preliminary research to guide further studies into the topic. The natural powdery gypcrete samples, with high gypsum contents and a lot of fine material, and five prepared samples of differing gypsum contents, were subject to falling-head permeability tests using both water and brine. It is understood that particle size distribution contributes to the hydraulic conductivity of soils, where a higher portion fines results in a lower hydraulic conductivity. In the case of gypcrete, the solubility is of significance as well, as it may have long term effects, through leaching and eventual cavity formation. With the intent of evaluating the effect of the aforementioned factors on the hydraulic conductivity of gypcrete in South Africa, the samples used represent differences in particle size distribution, gypsum content and origin. All samples, both natural and prepared, resulted in similar k values, in the order of 7.26x10-6 m/s, for water and the brine, despite the differences in properties. The results show that while the hydraulic conductivity is believed to be influenced by particle size distribution and origin, in the case of gypcrete in South Africa, on a small scale, it remained largely consistent. / Dissertation (MSc)--University of Pretoria, 2019. / Geology / MSc (Engineering Geology) / Unrestricted