Review of Sustainability in Self Compacting Concrete: the use of waste and mineral additives as supplementary cementitious material and aggregate.

Concrete is one of the commonly used construction materials, but there is a need to develop a new and sustainable technology to make concrete more affordable. With the advancement in technology, concrete was no longer seen as a three entity (binder, aggregate, and water). The unique workability properties of SCC make it unique in the concrete industry. This review assessed the materials, strength, rheological properties of agricultural waste, industrial waste and mineral additives in SCC production. The effect of the utilization of these additives and replacements on structural, mechanical and rheological properties of SCC was espoused. The review revealed that the use of both industrial and agricultural waste enhances the strength properties of SCC. Additionally, the use of agricultural waste improves the rheological properties of fresh concrete. The utilization of expansive material should be discouraged in SCC production. The review revealed that SCC developments ensure a good balance between deformability and stability. It was therefore recommended that SCC should be utilized in pavement construction, particularly when high axle load is expected

Variations of Density and Compressive Strength Before and After Charring of Some Selected Construction Timber Species of Southwestern Nigeria

This study aimed to evaluate the percentage variations of density and compressive strength of some selected timber species mostly used for constructional purposes in Southwestern Nigeria after undergoing fire exposure. The species are: Terminalia superba (Afara), Milicia excelsa (Iroko), Nauclea diderrichii (Opepe), Khaya ivorensis (Mahogany), Mansonia altissima (Mansonia), Tectona grandis (Teak).The densities and the compressive strengths of the species were determined at Moisture Contents (MC) of 9.0, 12.0, and 15.0%. Nine specimen per species, were exposed to fire at various temperature ranges.The results of analysis by variance revealed that at 9% MC, Mahogany had the lowest density value of 439±10.58Kg/m³. At 12 and 15% MC, Afara had the lowest density values of 444±4.18Kg/m³ and 469±7.07Kg/m³ respectively. At 9, 12 and 15% MC, Opepe had the highest density values of 630±28.85Kg/m³, 686±22.64Kg/m³ and 752±17.22Kg/m³ respectively. Afara of 9, 12 and 15% MC had the lowest compressive strength parallel to the grain values of 9.59±1.08N/mm2, 9.59±1.08N/mm2 and 8.13±1.01N/mm2 respectively, while Mahogany had the highest compressive strength parallel to the grain values of 16.57±0.50N/mm2, 15.17±0.49N/mm2 and 12.12±0.42N/mm2 at the three MC levels. Post fire exposure revealed that Afara had the highest percentage change in density and compression in parallel values, while both Iroko and Mahogany exhibited the lowest percentage change in density and compression in parallel values. This study indicated that Mahogany and Iroko species which had lowest post fire change in density and compression in parallel values are useful and recommended to ensure the safety in case of fire outbreaks

Investigation of the Properties of “Pure Water” Sachet Modified Bitumen

The increasing volume of traffic loads on our roads is currently a challenge on flexible pavement design and construction.  Factors such as durability, strength and economic needs have to be considered in the design and construction of road pavement.  Many researches have been conducted to explore supplementary material that can make a durable asphalt pavement. It is not unfamiliar that the modification of bitumen with the use of polymers enhances its performance characteristics but at the same time significantly alters its rheological properties. One of the environmental issues in most regions of Nigeria is the large number of polymeric wastes made from polyethylene water sachet (PWS) popularly called “Pure Water” Nylon deposited in domestic wastes and landfills. This study was conducted to investigate the effect of PWS on the properties of conventional bitumen and suitability of discarded PWS as bitumen modifier and to reduce the environmental effects of PWS disposal.  Bituminous blends containing PWS at various percentages 2.5%, 5%, 7.5%, 10%, 12.5% and 15% weight of conventional bitumen. Penetration, softening point and float tests were carried out on the samples to evaluate the penetration index, viscosity, stiffness modulus and the suitability of PWS as bitumen modifier. Sieve analysis and infrared spectroscopy of the shredded PWS sample were also carried out. Result obtained from tests was compared between control sample (0% PWS) and PWS modified samples. The test results show that PWSs influence more on the penetration of the modified sample with the increase in the viscosity of the bitumen as can be observed by the decrease in the value of penetration with the increase in concentration of PWS. The penetration index values of Samples 2.5% PWS and 7.5% PWS makes them to be classified as blown bitumen and the PI value of Sample 5% PWS makes it less susceptible to temperature changes and can be classified as oxidized bitumen. PWS is a cheap and readily available material in construction when used appropriately in bitumen and the recycling of PWS for asphalt base roads helps alleviate an environmental problem and saves energy. Keywords: Bitumen, pure water sachet (PWS), infrared spectroscopy analysis, penetration test, softening point, viscosity tes

Mechanical Properties of Dehydroxylated Kaolinitic Clay in Self-Compacting Concrete for Pavement Construction

The high increase in the cost of cement has led to a reduction in concrete production in most developing and under-developed countries. Therefore, the need for a sustainable and cost-effective substitute for cement is necessary. This research focused on the application of dehydroxylated kaolinitic clay in the production of self-compacting concrete for pavement construction. The elemental and oxide composition of the cementitious material (cement and metakaolin) was assessed using atomic absorption spectrometry and a scanning electron microscope was used to determine the particle geometry. Six mixtures of SCC with 0%, 5%, 10%, 15%, 20% and 25% metakaolin replacement were incorporated into this concrete mix. The passing ability,segregation ability and the flowing ability of the fresh concrete were assessed. The strength properties of the various mixtures (compressive and flexural) of the samples were also assessed at 3, 7, 14, and 28 days. The rheological properties showed that the addition of dehydroxylated kaolinitic clay higher than 10% showed poor rheology. However, percentages greater than 15% gave a reduction in compressive strength and flexural strength. In a bid to encourage sustainability in road construction and adopt the use of eco-friendly material, metakaolin is a viable material

Self-compacting concrete in pavement construction: Strength grouping of some selected brands of cements

This paper investigates strength properties of some selected cement brands for self-compacting concrete application in pavement construction. Three brands each of Portland limestone cement grades, CEM II/A-L 42.5 (Brand A), CEM II/B-L 32.5 (Brand B) and CEM II/B-L 32.5 (Brand C), were used. Rheological test was carried out using the L-Box, V-Funnel and slump cone while compressivegas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decreas

DEVELOPMENT OF MELTED EXPANDED POLYSTYRENE AS ΒITUMEN MODIFIER FOR PAVEMENT CONSTRUCTION

This study was designed to investigate the Performance of melted Expanded Polystrene (EPS) wastes on the quality of bitumen used in asphaltic concrete. The EPS materials were ground and then melted (200-400 oC) to form a slurry. Specific gravity of the EPS and chemical composition were determined by AAS analyses. The melted EPS was used as a modifier in mix proportions of 0, 2.5, 5, 7.5 and 10% by weight of bitumen. The 5% unmodified bitumen content obtained from the Marshall mix design was used to prepare asphalt concrete samples with 0 to 10% contents of melted EPS. The products were tested for Marshall stability, specific gravity, penetration, softening point, ductility, loss on heating, viscosity, flash and fire points and the melting point tests using standard methods. The ground EPS was uniform and well-graded (4.750-0.010 mm) with a specific gravity of 0.012, having a styrene structure with methanol on the ring. The specimen prepared with the specified mix proportion of EPS produced results that ranged between 5598.71-16937.70 N for Marshal stability; 2.02-3.54 for specific gravity; 129-152 mm for penetration; 42.80-47.50 oC for softening point; 75.00-32.90 cm for ductility; 0-3.48% for loss on heating; 208-2204 sec.STV for viscosity; 243.3-269.0 oC for flash point; 196.1-211.0 oC for melting point. The results also showed that with correlation coefficients ranging from r = 0.658-0.999, there is a strong positive correlation between the improvement exhibited in the specimen tested properties and melted EPS used in bitumen. At the 5% bitumen with 5% EPS by weight of asphalt concrete, the results of stability, flow and optimum bitumen content satisfied the British Standard Specification framework for polymer-modified bitumen and it is therefore suitable for flexible pavement construction

DEVELOPMENT OF MELTED EXPANDED POLYSTYRENE AS ΒITUMEN MODIFIER FOR PAVEMENT CONSTRUCTION

This study was designed to investigate the Performance of melted Expanded Polystrene (EPS) wastes on the quality of bitumen used in asphaltic concrete. The EPS materials were ground and then melted (200-400 oC) to form a slurry. Specific gravity of the EPS and chemical composition were determined by AAS analyses. The melted EPS was used as a modifier in mix proportions of 0, 2.5, 5, 7.5 and 10% by weight of bitumen. The 5% unmodified bitumen content obtained from the Marshall mix design was used to prepare asphalt concrete samples with 0 to 10% contents of melted EPS. The products were tested for Marshall stability, specific gravity, penetration, softening point, ductility, loss on heating, viscosity, flash and fire points and the melting point tests using standard methods. The ground EPS was uniform and well-graded (4.750-0.010 mm) with a specific gravity of 0.012, having a styrene structure with methanol on the ring. The specimen prepared with the specified mix proportion of EPS produced results that ranged between 5598.71-16937.70 N for Marshal stability; 2.02-3.54 for specific gravity; 129-152 mm for penetration; 42.80-47.50 oC for softening point; 75.00-32.90 cm for ductility; 0-3.48% for loss on heating; 208-2204 sec.STV for viscosity; 243.3-269.0 oC for flash point; 196.1-211.0 oC for melting point. The results also showed that with correlation coefficients ranging from r = 0.658-0.999, there is a strong positive correlation between the improvement exhibited in the specimen tested properties and melted EPS used in bitumen. At the 5% bitumen with 5% EPS by weight of asphalt concrete, the results of stability, flow and optimum bitumen content satisfied the British Standard Specification framework for polymer-modified bitumen and it is therefore suitable for flexible pavement construction