Properties of mortar and concrete containing fine sand contaminated with light crude oil

Sand contaminated with crude oil has become a major environmental concern worldwide. This problem poses threats to human health, the ecosystem, and the properties of the surrounding sand. Due to the prohibiting cost of the existing remediation methods, a more cost-effective way of utilizing oil contaminated sand is warranted. Mixing oil contaminated sand with cement and using this mix as alternative construction material is considered an innovative approach to reduce its environmental impact. This study is the first to investigate the effect of light crude oil on the physical and mechanical properties of fine sand, and mortar and concrete where contaminated sand is an ingredient. This approach is a critical step to sufficiently evaluate the suitability of this waste product as a sustainable building and construction material. In the first stage, an extensive experimental study was conducted on the important geotechnical properties of fine sand contaminated with light crude oil. The results showed that water absorption, permeability, contact angle, frictional angle, and cohesion decreased with high levels of oil contamination. However, these properties of fine sand were enhanced at 1% oil contamination. The highest value of cohesion (10.76 kPa) and 10% enhancement in shear strength was observed at this oil contamination level. More importantly, the results of this stage provided information on the suitability of using this waste material as fine aggregates in mortar and concrete. The second stage consisted of an evaluation of cement mortar properties containing fine sand contaminated with light crude oil. Mixing cement and water before adding the oil contaminated sand yielded up to 19% higher compressive strength compared to the cement mortar prepared by mixing the sand and cement before adding the water, due to a better reaction of cement particles and water during the hydration process. Similarly, curing in a fog room produced mortar of up to 45.6% higher compressive strength compared to mortars cured under other curing conditions, i.e. in water, in air, and in plastic bags. The scanning microscope observations revealed that cement mortars cured in the fog room had lower total porosity, smaller capillary pores, and denser calcium silicate hydrate compared to those cured under other methods. A w/c ratio of 0.5 was found to produce cement mortar with a higher compressive strength than mortar with a w/c ratio of 0.4 or 0.6. It was also found that the cement mortar with sand having more than 2% oil contamination requires a longer curing period to fully develop its compressive strength. The results of this stage demonstrated that proper mixing and curing methods, w/c ratio, and reasonable curing time are important for a cement mortar containing oil contaminated sand to achieve reasonable physical and mechanical properties for building and construction. An investigation of the suitability of a geopolymer binder to produce mortar containing oil contaminated sand was investigated during the third stage. It was found that heat curing can increase the compressive strength of geopolymer mortar up to 54% compared to ambient curing situation. The geopolymer mortar with 1% of light crude oil contamination yielded a 20% higher compressive strength to mortar containing sand with a saturated surface dry condition. This was due to the high alkalinity of the solution, leading to the generation of more geopolymeric binder. Similarly, the formation of efflorescence decreased as the level of oil contamination decreased due to light crude oil filling up the pores. From this stage, it was demonstrated that geopolymer mortar containing oil contaminated sand has the potential as a new engineering material which has a positive impact on the environment. An investigation of the properties of concrete containing oil contaminated sand was implemented as the last stage. The results of the investigation showed that the density of concrete deceased as the amount of crude oil increased due to an increase in the surface voids and total porosity. The highest compressive and splitting tensile strength was obtained for concrete with 1% of light crude oil contamination due to the oil optimising the sand cohesion. Above 1%, the bond between the cement paste and aggregates was affected, resulting in a decrease in strength properties. The developed simplified prediction equations to estimate the compressive strength of mortar and concrete containing fine sand contaminated with light crude oil gave a 98% accuracy between the experimental results and the predicted values. An enhanced understanding of the behaviour of fine sand contaminated with light crude oil and the properties of mortar and concrete utilising this waste material is the outcome of this investigation. This outcome will provide a benchmark for future studies and useful information to carefully consider oil contaminated sand for use in building and construction, and as a cost-effective alternative remediation method

Oil Contaminated Sand: Sources, Properties, Remediation, and Engineering Applications

Oil leakage during the exploration, production, and transportation of crude oil is a significant issue worldwide because crude oil spills severely impact the physical and chemical properties of the surrounding soil. A range of remediation methods for oil-contaminated soil is recommended, consisting of sand washing, bioremediation, electro-kinetic sand remediation, and thermal desorption; however, none are cost-effective. To find a suitable alternative remediation method, oil-contaminated sand utilisation in construction was considered. Several researchers found that oil contamination generally has an adverse effect on the mechanical properties of sand, but certain levels of contamination have beneficial effects on some of the important properties of the sand and its produced concrete. This chapter reviews the main sources of oil contamination and the existing remediation methods for this waste material. It analyses the different factors that affect the properties of oil-contaminated sand and concrete, including the type of crude oil and permeability of sand, like its properties, absorption, chemical composition, and spillage quantity. Furthermore, the intensive evaluation results of light crude oil effects on the geotechnical properties of fine sand, cement mortar and concrete were presented. Potential applications for oil-contaminated sand were also identified for the re-use of this material in engineering and construction

Oil contaminated sand: an emerging and sustainable construction material

Crude oil spillage severely impacts the environment and affects the physical and chemical properties of the surrounding soil. Due to prohibitive cost of cleaning and disposing oil contaminated sand, mixing and stabilizing them with cement and using them in construction is now considered as an alternative and cheap remediation method. In this paper, the effect of o il contamination on the mechanical properties of sand and its concrete were reviewed . In addition, the results of the on-going research and development on the effects of light crude oil contamination on the properties of fine sand and the produced mortar are presented. For fine sand contaminated with light crude oil, it was found that the cohesion increased significantly up to 1% of oil contamination and then decreased with increasing percentage of crude oil while a slight reduction in frictional angle was observed with oil contamination. The highest compressive strength was obtained for mortar with 1% oil contamination and with only a 18% decrease in strength of mortar with 10% oil contamination compared to the uncontaminated samples. More importantly, the compressive strength of mortar with oil contaminated sand was found suitable for some engineering applications indicating their high potential and beneficial use as an emerging and sustainable material in building and construction

Influence of Elevated Temperature on the Mechanical Properties of Hybrid Flax-Fiber-Epoxy Composites Incorporating Graphene

Natural fibers are now becoming widely adopted as reinforcements for polymer matrices to produce biodegradable and renewable composites. These natural composites have mechanical properties acceptable for use in many industrial and structural applications under ambient temperatures. However, there is still limited understanding regarding the mechanical performance of natural fiber composites when exposed to in-service elevated temperatures. Moreover, nanoparticle additives are widely utilized in reinforced composites as they can enhance mechanical, thermal, and physical performance. Therefore, this research extensively investigates the interlaminar shear strength (ILSS) and flexural properties of flax fiber composites with graphene at different weight percentages (0%, 0.5%, 1%, and 1.5%) and exposed to in-service elevated temperatures (20, 40, 60, 80, and 100 °C). Mechanical tests were conducted followed by microscopic observations to analyze the interphase between the flax fibers and epoxy resin. The results showed that a significant improvement in flexural strength, modulus, and interlaminar shear strength of the composites was achieved by adding 0.5% of graphene. Increasing the graphene to 1.0% and 1.5% gradually decreased the enhancement in the flexural and ILSS strength. SEM observations showed that voids caused by filler agglomeration were increasingly formed in the natural fiber reinforced composites with the increase in graphene addition

Long-Term Water Absorption of Hybrid Flax Fibre-Reinforced Epoxy Composites with Graphene and Its Influence on Mechanical Properties

Interest in the use of natural fibres as an alternative for artificial fibres in polymer composite manufacturing is increasing for various engineering applications. Their suitability for use in outdoor environments should be demonstrated due to their perceived hydrophilic behaviour. This study investigated the water absorption behaviour of hybrid flax fibre-reinforced epoxy composites with 0%, 0.5%, 1% and 1.5% graphene by weight that were immersed in water for 1000, 2000, and 3000 h. The flexural and interlaminar shear strength before and after immersion in water was then evaluated. The results showed that graphene nanoparticles improved the mechanical properties of the composites. The moisture absorption process of hybrid natural fibre composites followed the Fickian law, whereas the addition of graphene significantly reduced the moisture absorption and moisture diffusion, especially for hybrid composites with 1.5% graphene. However, the flexural and ILSS properties of the composites with and without graphene decreased with the increase in the exposure duration. The flexural strength of hybrid composites with 0%, 0.5%, 1% and 1.5% graphene decreased by 32%, 11%, 17.5% and 13.4%, respectively, after exposure for 3000 h. For inter-laminar shear strength at the same conditioning of 3000 h, hybrid composites with 0.5%, 1% and 1.5% graphene also decreased by 13.2%, 21% and 17.5%, respectively, compared to the dry composite’s strength. The specimens with 0.5% graphene showed the lowest reduction in strength for both the flexural and interlaminar tests, due to good filler dispersion in the matrix, but all of them were still higher than that of flax fibre composites. Scanning electron microscope observations showed a reduction in voids in the composite matrix after the introduction of graphene, resulting in reduced moisture absorption and moisture diffusion

Physical and mechanical properties of cement mortar containing fine sand contaminated with light crude oil

Oil contaminated sand resulting from oil leakage has continuously been a major environmental concern worldwide. This problem affects the physical and chemical properties of the surrounding soil. Due to prohibitive cost of the existing remediation methods for oil contaminated sand, mixing them with cement and using in construction is considered as a cheaper alternative. In this study, the effect of light crude oil contamination on the physical and mechanical properties of cement mortar was investigated. Fine sand with different percentages of light crude oil by weight ranging from 0% to 10% was mixed with Ordinary Portland cement and cured in a fog room. The compressive strength of the cement mortar was then determined at 7, 14 and 28 days. Results showed that the workability and the total porosity of the cement mortar increased as the amount of crude oil increases. Moreover, the compressive strength increased with the increasing curing time for all specimens. The cement mortar containing fine sand with 1% light crude oil exhibited the highest compressive strength, which is 18%, 30% and 17% higher than the uncontaminated samples at 7, 14 ad 28 days, respectively. Interestingly, the cement mortar with up to 2% oil contamination has higher compressive strength than the 0% oil contamination while increasing the crude oil content more than 2% and up to 10% cause a reduction in the compressive strength by 50%. Still, the strength properties of mortar with oil contaminated sand up to 10% are suitable for landfill layering and production of bricks results indicating their high potential and beneficial use as a sustainable material in civil engineering and construction

Properties and structural behavior of concrete containing fine sand contaminated with light crude oil

Mixing crude oil contaminated sand with cement and using this mix as an alternative construction material is considered an innovative and cost-effective approach to reduce its negative environmental impact. In this study, the compressive and splitting tensile strength of concrete with different levels of light crude oil contamination (0, 1, 2, 6, 10 and 20%) were evaluated. Microstructure observation was also conducted to better understand better on how the oil contamination is affecting the concrete properties. The bond strength of steel reinforcement and a comparative evaluation of the flexural behaviour of steel reinforced beams using concrete with 0% and 6% oil contamination was carried out. Results showed that concrete with light crude oil contamination can retain most of its compressive and splitting tensile strength at a contamination level of up to 6%. A good bond between the steel reinforcement and concrete can be achieved up to this level of oil contamination. The concrete beam with 6% oil contamination exhibited only a 20% reduction in the moment capacity compared to a beam using uncontaminated concrete. Simplified empirical equations were also proposed to reliably predict the mechanical properties of concrete containing oil contaminated sand

Behavior of circular concrete columns reinforced with hollow composite sections and GFRP bars

Hollow concrete columns (HCCs) constitute a structurally efficient construction system for marine and offshore structures, including bridge piers and piles. Conventionally, HCCs reinforced with steel bars are vulnerable to corrosion and can lose functionality as a result, especially in harsh environments. Moreover, HCCs are subjected to brittle failure behavior by concrete crushing due to the absence of the concrete core. Therefore, this study investigated the use of glass fiber- reinforced polymer (GFRP) bars as a solution for corrosion and the use of hollow composite- reinforced sections (HCRSs) to confine the inner concrete wall in HCCs. Furthermore, this study conducted an in-depth assessment of the effect of the reinforcement configuration and reinforcement ratio on the axial performance of HCCs. Eight HCCs with the same lateral- reinforcement configuration were prepared and tested under monotonic loading until failure. The column design included a column without any longitudinal reinforcement, one reinforced longitudinally with an HCRS, one reinforced longitudinally with GFRP bars, three reinforced with HCRSs and different amounts of GFRP bars (4, 6, and 8 bars), and three reinforced with HCRSs and different diameters of GFRP bars (13, 16, 19 mm). The test results show that longitudinal reinforcement—whether GFRP bars or HCRSs—significantly enhanced the strength and displacement capacities of the HCCs. Increasing the amount of GFRP bars was more effective than increasing the bar diameter in increasing the confined strength and the displacement capacity. The axial-load capacity of the GFRP/HCRS-reinforced HCCs could be accurately estimated by calculating the load contribution of the longitudinal reinforcement, considering the axial strain at the concrete peak strength. A new confinement model considering the combined effect of the longitudinal and transverse reinforcement in the lateral confinement process was also developed

Rheological properties of blended metakaolin self-compacting concrete containing recycled CRT funnel glass aggregate

Rheology is a field of fluid mechanics that studies the flow of materials and the interaction between stress states and deformation according to their viscosity, elasticity and plasticity and with the appearance of new materials and the complex behaviour of concrete pumpability, since the field of civil engineering is interested in the study of concrete flow. This work will examine how the use of catodique ray tube (CRT) glass as sand replacement in proportions of 0, 10, 20, 30, 40 and 50%, and metakaolin (MK) powder in proportions of 5, 10 and 15% will affect the rheological properties of self-compacting concrete (SCC). In this investigation, the flow ability of SCC was evaluated by slump flow, L-Box, and V-funnel tests. Its resistance to segregation was measured by the sieve stability test and the yield stress and plastic viscosity was determined by a modified slump test. This investigation concluded that CRT glass improved the rheological properties and minimised the dosage of superplasticiser (SP); the best results came from concrete with 50% of CRT sand glass. This improvement helps to overcome the negative effect of MK in SCC pumpability and reduces the time of casting. An acceptable relationship between rheological properties shows that a modified slump test can be used to evaluate yield stress and viscosity. Keywords: CRT, metakaolin, rheological properties, self-compacting concrete Kulcsszavak: CRT, metakaolin, reológiai tulajdonságok