Papers by Keyword: Pavement

Abstract: This study investigates the effects of microcellulose (MCC) and styrene-butadiene (SB) emulsion on the properties of cement-stabilized soil. The addition of MCC to cement-stabilized soil resulted in a reduction in hydraulic conductivity due to its water absorption properties, although it did not significantly improve mechanical properties. In contrast, SB emulsion modified cement-stabilized soil exhibited increased toughness and ductility, transitioning from brittle to ductile behavior. Interestingly, the combination of SB emulsion and MCC yielded a gradual decrease in hydraulic conductivity with increasing SB emulsion content. This was attributed to SB emulsion coating the surface of MCC particles, reducing their water absorption capacity and altering their influence on water flow through the soil-cement matrix. Overall, while MCC alone had limited impact on mechanical properties, SB emulsion showed promise for enhancing toughness and ductility. These findings underscore the importance of understanding additive interactions and their effects on the properties of cement-stabilized soil. Further research is needed to optimize additive compositions for specific engineering applications.

Abstract: In geotechnical engineering, the enhancement of soil properties is crucial for cost-effective construction practices. This study investigates the impact of incorporating microcrystalline cellulose into styrene-butadiene emulsion modified cement-stabilized soils. The mechanical properties, including unconfined compressive strength (UCS) and indirect tensile strength (ITS), were evaluated alongside morphological analysis using scanning electron microscopy. Results indicate that the addition of microcrystalline cellulose influences the mechanical behavior of the composite material in a nuanced manner. At lower microcrystalline cellulose content (1%), an improvement in tensile strength is observed due to enhanced interfacial bonding between cellulose hydroxyl groups and styrene-butadiene emulsion surfactants. However, at higher microcrystalline cellulose content (2% and 3%), a reduction in tensile strength occurs, attributed to hindered cement hydration. Nonetheless, the incorporation of styrene-butadiene emulsion contributes to the transition from brittle to ductile behavior, enhancing toughness. Morphological analysis corroborates these findings, highlighting the complex interactions between microcrystalline cellulose, styrene-butadiene emulsion, and cement-stabilized soils. This study provides valuable insights for optimizing the mechanical performance of polymer-modified cement-stabilized soils, paving the way for the development of sustainable construction materials with improved resilience and durability.

Abstract: This research focuses on the modification of Natural Rubber Latex (NRL) for its application in soil-cement pavement. The NRL was modified with Coumarone-Indene (CI) and various tests were conducted to evaluate the effects of this modification. The degree of swelling test showed that the NRL's ability to absorb and retain toluene solvent was influenced by the addition of CI. The tensile tests revealed that the inclusion of CI improved the tensile modulus and tensile strength of the NRL up to an optimal content, beyond which there was a decrease. Peel strength tests demonstrated that the incorporation of CI initially increased peel strength up to an optimal CI content, after which it decreased. The splitting tensile test and the unconfined compressive test indicated that soil-cement blends containing modified NRL with CI 8 phr exhibited higher splitting tensile strength and unconfined compressive strength compared to those with neat NRL. Overall, the modification of NRL with CI showed promise in enhancing the properties of soil-cement pavement materials. The findings contribute to the understanding of modifying NRL for pavement applications and provide insights for further research and development in this field.

Abstract: The present research aims to simultaneously have positive contribution in two environmental issues identified on global scale, but also locally, in Romania: the waste generation due to industrial processes, on one hand, and on the other hand, the exhaustible natural resources constant increasing demand and consumption, in the construction industry as well. The use of abrasive waterjet (AWJ) sand in specific industries, for material processing purpose, represents an advantageous and efficient methodology, with increased domain of applicability and experiencing a significant development and improvement in the last years; still, besides the numerous benefits of the AWJ cutting and material processing techniques, they also generate collateral by-products, mostly converted into wastes: the abrasive materials (Garnet Sands) used during the AWJ cutting generate a sludge, generally unutilized and randomly deserted into damps (Spent Garnets, SG). In the same time, the construction industry and the corresponding mortar and concrete production segments, present accelerated growth, associated with global population fast increase (mainly in urban poles) and also with the industrial drive. The population growth and the industry expansion demand the corresponding infrastructure, civil, industrial, agrozootechnical, road and energetic, etc., leading to related request for building materials, concrete and natural resource consumption, like aggregates. This was the context which induced the idea of potentially valorizing the SG industrial by-products, generated by the local AWJ cutting industry, into construction materials, namely fine grain aggregates substitution in mortar and concrete. In order to evaluate the waste compatibility to a typical composition of cementitious material, a regular mortar was developed, considered the Reference (R) and further partial substitution of the usual sand was performed, by using the Spent Garnet wastes generated by two local companies. The substitution percentage was established in accordance to the previous studies in the topic, and ranged from 10 to 50% with respect to the sand quantity in the Reference mix. The mechanical performance of the mortars was analyzed at specific ages, in order to establish the viability of the substitution: 7day-testing, 14-day testing, 28 day-testing. The first results of the experimental study, focused on mechanical and physical characteristics of the mixes, are clearly encouraging, leading to the conclusion that SG by-products could be efficiently integrated in concrete and mortar mixes, as partial replacement of the regular sand; thus, the study opens the path to a sustainable, preventive solution for industrial waste generation and natural resources consumption as well. The potential use of SG as aggregate partial replacement in pavement eco-blocks is also considered, as future direction of research.

Abstract: The increase in the production and utilization of plastics has created a never-ending problem of plastic waste. Developing countries face challenges with plastic waste disposal that in due process negatively impacts the environmental ecosystem. That notwithstanding, it suffices to mention that most developing countries have poor road networks that pose a burden towards smooth economic and social development. The problem is further exacerbated by the limited availability of bitumen which is usually imported but also has environmental concerns. It is against this background that we proposed alternative binders from plastic waste which can help developing countries to manage plastic waste as well as build road networks, thereby leading to sustainable development. We explored the 80/100 penetration grade bitumen modification (Penetration grade 85 and Softening temperature 46°C) using polyethylene terephthalate (PET) waste (2 – 12%) and lignin (0.2%) as a crosslinking agent by weight for every PET waste – Bitumen sample. The research showed that Plastic waste and lignin improved the performance of bitumen. The modified bitumen with 10% waste PET and 0.2% lignin enhanced the softening point and penetration points to 55°C and 46, respectively; hence the incorporation of PET and lignin provided better properties compared to the neat bitumen.

Abstract: This paper presents the comparison between sediment and natural subgrade material for road construction to check its stability to improve soil properties. Two samples were investigated which are sediment and subgrade construction material which were taken from Wilayat A’seeb, Oman. Sediment was collected from Alkhoud dam, Muscat, and subgrade construction material was collected from Al Mubilah construction site, Muscat. Elemental analyses and mechanical tests were conducted to achieve the purpose of the study. According to the AASHTO classification, the result of the sediment samples shows that it was silty and clayey gravel A-2-4 and clayey sands or sandy clay mixtures according to USCS classification. Also, investigations on the subgrade construction material show that it was silty and clayey gravel and sand A-2-7 according to AASHTO classification and well-graded sands, gravelly sands according to USCS. The result of grain size distribution curves shows that subgrade soil is applicable to be used but sediment is not applicable as pavement construction and. The maximum dry density (MDD) and optimum moisture content (OMC) of the sediment sample are 1.422 g/cm³ and 20.3% respectively. Also, the maximum dry density (MDD) and optimum moisture content (OMC) of the subgrade construction material are 1.634 g/cm³ and 15.5 % respectively. As compared between the two materials, it found that the result of maximum CBR value of subgrade material was 16.13% and the maximum CBR value of sediment material was 16.07% and that means both materials are very close in strength and sediment has the power to be used in road construction with some improvement. According to the experimental results, it shows that the investigated sediment and natural subgrade soil are suitable to be used in the subgrade layer because it is corresponding to the range of Omani standards but it is not suitable to be used as subbase and base layers. Other standards might be compatible with the results to be effective use in subbase and base layers.

Abstract: Pavement materials have developed significantly through many stages until they have reached what they are now. Despite the fact that there are many samples found in Oman which are not used or neglected, there are lots of natural samples can be depleted because of its huge use like the natural materials. Basically, the frequent’ use has a negative impact on nature. Accordingly, this study is going to shed lights on some considered samples that exist but are not used called waste products under some justifications and tests of particular samples classified as coarse-grained soil (coastal material, waste brick construction, desert sand) through some methodologies: Grain Sieve Analysis, Atterberg Limit Test, Clay Content Test, Proctor Compaction Test, and California Bearing Ratio test. The mechanical properties of these samples are tested to evaluate their efficiency and effectiveness in the paving layers. The most important parameter used in the evaluation process is the CBR and the sieve analysis. As a final result, it turns out that most of the samples are not complied with Oman's specifications for subbase and base use but some materials like Khour Al-Hamam can be modified using additive materials to be suitable.

Abstract: Improving the reliability and durability of sidewalks, footways, car parks and areas for various purposes, made of concrete paving blocks (CPBs), is an important task of construction. In order to improve the quality characteristics, new pavements consisting of concrete paving blocks with a ribbed underside surface are proposed. Hypotheses about the advantages of the developed structural solutions of pavements relative to traditional pavements of blocks with a flat underside surface were formulated. To confirm the hypotheses, studies of one of the developed pavement variants of in laboratory conditions were performed. The article describes the plan and methodology for implementation two series of experiments. In the first series of the experiment, a section of a traditional pavement of concrete blocks with a flat underside surface was investigated, in the second, a section from a pavement of concrete paving blocks with a ribbed underside surface consisting of three prismatic elements. Qualitative characteristics of the pavement are determined by various indexes. As a result of laboratory tests, the dynamics of settlement of experimental CPBs under the influence of vertically applied load was studied, and density index of a sand structural layer located under the tested CPBs was also obtained. The settlement indexes of the tested CPBs were investigated for three days. A comparative analysis of the experimental results confirmed the hypothesis about the advantages of pavements of concrete paving blocks with a ribbed underside surface. For the further implementation of the developed pavement variant in the construction industry, additional research is required. Further research directions of pavements of concrete paving blocks with a modified geometric shape of the underside surface are determined.

Abstract: Cement is the most utilized construction material. The energy-intensive processes that are involved in its production contribute up to 10% of total global CO₂ emissions, with potentially adverse environmental implications. It is however possible, that energy and cost efficiency can be achieved by reducing on the amount of clinker, and in its place utilising supplementary cementitious materials (SCMs) or pozzolans that require less process heating and emit fewer levels of CO₂. Currently, most sustainable concrete uses either GGBS (slag) or PFA (fly ash) to reduce the quantity of cement used in construction and highways applications. GGBS and PFA come from industries (steel and coal waste respectively) which are in decline that should not be relied upon in the long term. This report shows that cement in concrete can also be replaced with rice husk ash (RHA) which actually enhances the mechanical properties. RHA comes from the food production industry and is vital for the growing global population. It is thus a socially responsible objective to use a pozzolan in civil engineering applications that is sourced from an environmentally friendly and sustainable industry. This study investigated the potential of RHA to be used as a SCM by evaluating mechanical properties. Experiments were carried out by supplementing cement in concrete mixes with RHA at up to 10% replacement by mass. Results were compared with a control specimen (100% cement), with a water/binder (w/b) ratio of 0.4 and C32/40 design mix using CEM I. The results show excellent early age strengths with all RHA mixes surpassing 40 MPa strength within 7 days which is contrary to general trends in SCM concrete where strength development is slow in the initial stages in comparsion to 100% cement concrete. All RHA specimens exhibited impressive flexural and tensile strengths.

Abstract: This article deals with the evaluation of the effects on soil caused by leaching of materials from curbs, which were made using cement kinl dust from the cement plant Horné Srnie. Attention is also paid to a condition of the grass growing near the curbs. These laboratory curbs (bricks) were produced with addition of cement kiln dust and fly ash after denitrification by the SNCR method in alkaline activated materials based on blast furnace slag granules activated by anhydrous disodium metasilicate During the experiment the effects of laboratory curbs on grass growth in testing flower pots were investigated. The aim of the experiment was to obtain a product suitable for curbs with supposed direct contact with the soil. The experiment dealt with the properties of laboratory curbs stored in situ as well as with their influence on the soil and the effect of leached substances on the surrounding grass. The main part of the experiment was conducted in situ.