Suitability Assessment of Construction and Demolition Waste as a Highway Material

For Being a developing country urbanization is growing rapidly in Bangladesh and there has been a significant increase in the construction of roads. But due to lack of financial aid many of the roads are still unsealed. However, not only the utilization of Construction and Demolition Waste (CDW) in flexible pavement will be helpful for the reduction of road construction costs but also it will help to reduce environmental pollution which may be caused by disposing CDW in open area. The objective of this research is to utilize the CDW in base and sub base layers in the flexible pavement design to reduce the cost of road construction and environmental pollution. Proceeding by collecting CDW like brick from demolished building and conventional brick from kiln, a no of standard test conducted in laboratory namely Aggregate Impact Value, Crushing Value, Specific Gravity, Water Absorption and Loss Angeles Abrasion Test for three times. After analyzing the test results, we found that the average Aggregate Impact Value for CDW and Conventional Aggregate (CA) are respectively 29.52% and 23.87%, Aggregate Crushing value for CDW and CA are respectively 28.10% and 22.88%, Los Angeles Abrasion value for CDW and CA are respectively 31.47% and 28.52%, specific gravity value for CDW and CA both is 1.75, water absorption for CDW and CA are respectively 7.62% and 12.23%. After analyzing the test results and comparing with the standard value, we figure out that the CDW are useful for using base and sub base layers in the flexible pavement.

Evaluation of the viability of recycling railroad ballast for reusing in railroads

The main objective of this study is to assess the reuse of naturally old ballast that was removed from an operating railroad. In order to verify the viability of its reuse, laboratory tests were carried out, based on the procedures and parameters established in literature. The reuse of ballast would reduce costs, minimize the disposal of this material and reduce quarry extraction. There are several standards regulations the ballast’s (gravel) properties, such as size, shape, hardness, abrasion resistance and composition to provide better performance of the rail platform, due to the wide variety of materials and environmental conditions to which they are subjected. Ballast specifications are based on the execution of characterization tests and can be divided according to strength properties and geometric properties. Thus, several specifications have been used by different railway organizations around the world to meet the needs of their projects. One test used to analyze ballast quality is the Los Angeles Abrasion, which provides data on resistance to fragmentation. The durability of the ballast depends on the quality of the gravel related to the original rock composition. This is an important parameter that can be associated with railroad maintenance, which is expensive. A series of tests were carried out to evaluate the ballast properties, as well as an analysis of the geometric and mineralogical characteristics of the gravel, and the impact of the variation of these properties in the performance of the ballast. The viability of reusing the ballast removed from an operating road was then evaluated, and it was concluded that the material is still suitable for reusing, although its properties have undergone a few changes, without modifying its main characteristics and functions.

Characterization of TBM Muck for Construction Applications

This paper investigates the potential utilization of the Tunnel Boring Machine (TBM) muck generated from Doha’s Metro Gold Line in different construction applications. The properties of the raw TBM muck were studied, and the results were compared to the specifications of Qatari Construction Standards (QCS 2014) of concrete aggregates, fill material under buildings and road subgrades. Compared to the requirements of concrete aggregates, the results indicated that the gradation of the raw TBM muck does not comply with the QCS 2014 requirements, and hence, sieving and screening may be essential. Moreover, the tests’ results showed that the properties of the muck meet the requirements of the concrete coarse aggregates, except for the water absorption, loss by magnesium sulphate soundness, loss by Los Angeles abrasion and the acid-soluble sulphate. As fill material under buildings or road subgrades, the gradation of the TBM muck complies with the QCS 2014 requirements, while the liquid limit and plasticity index are higher than the QCS 2014 permissible limits. Additionally, the morphological structure and the elemental composition of the raw TBM muck were determined by employing Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX), respectively. Digital images were also taken at larger scale to draw a full picture of the TBM muck morphology. A mixture of rough-rounded to angular-elongated shaped particles with relatively large voids could be observed. The EDX analysis demonstrated the presence of silicon (Si) as the predominant component of the muck, which may alter the Coefficient of Thermal Expansion (CTE) values for mixtures prepared using TBM muck. Hence, further investigations should be performed on the mechanical and thermal properties of mixtures containing TBM muck as aggregates’ replacement, and further work should be directed toward this end.

The Suitability of Tigris River Sediments from Tikrit, Northern Iraq, for Concrete Production and Road Construction Purposes

This study aims to assess the suitability of the sediments present in Tigris River, Tikrit city, northern Iraq for concrete production and road building purposes. Representative samples were collected from three selected stations at the study area using the channel modeling method. According to the grain size analysis, the sediments were classified as a type of poorly graded gravels (GP) depending on the unified soil classification system. The true specific gravity of the soil ranged between 2.28 and 2.568. The chemical analysis of the study samples revealed that gypsum content ranged between 0.82 and 1.69 %. Total soluble salts ranged 2.45- 3.87%, the organic matter content ranged 0.14- 0.76%, and the pH value was between 7.73 and 7.38%. The results of the Los Angeles Abrasion Test of selected samples showed weight loss ratios for the three stations (1, 2, and 3) of 19.9, 20.7, and 17.2%, respectively, while the maximum dry density values were 2.2739, 2.1940, and 2.2013 gm / cm3, respectively. The values ​​of the Californian Bearing Ratio test (C.B.R) were 53, 65 and 106 %, respectively. After comparing the results with the standard values of ASTM for concrete and roads materials, it was found that the samples were suitable for these purposes.

Influence of Aggregates on Stripping Behavior of Bituminous Mixes

Moisture damage leads to premature failure of flexible pavements. The removal of bituminous coating from aggregates lead to the disintegration of bituminous mixes and is known as stripping. Various mechanisms and factors have been identified to play a role in the process, properties of aggregates being one of the major factors. This study is an attempt to analyze the influence of chemical, mineralogical and physical properties of aggregates on the stripping propensity of the loose mix. For this purpose, aggregates are chosen from six different quarry sites with diverse chemical compositions used for construction and maintenance of a large network of roads. Stripping tests are thereafter conducted on the aggregates using different percentage of hydrated lime. The amount of hydrated lime required for the prevention of stripping for concerned aggregate sources is determined. The research leads to the findings that the presence of elements such as silicon and potassium leads to a decrease in bond strength whereas the presence of calcium, sodium, iron, magnesium and aluminium enhanced the bond strength. Statistical tools and techniques are used to verify the results. Comparatively softer aggregates showed lesser resistance to stripping which could be inferred from aggregate impact and Los Angeles abrasion tests. The findings of the study can be helpful in the selection of aggregates with different chemical content for bituminous road construction depending upon the sensitivity to stripping. Doi: 10.28991/cej-2021-03091671 Full Text: PDF

EVALUATING THE SAWABILITY OF ROCKS BY CHAIN-SAW MACHINES USING THE PROMETHEE TECHNIQUE

One of the most significant factors in the estimation of dimension stone quarry cost is the production rate of rock cutting machines. Evaluating the production rate of chain-saw machines is a very significant and practical issue. In this research, it has been attempted to evaluate and select the suitable working-face for a quarry by examining the maximum production rate in the Dehbid and Shayan marble quarries. For this purpose, fi eld studies were carried out which included measuring operational characteristics of the chain-saw cutting machine, the production rate and sampling for laboratory tests from seven active case studies. Subsequently, the physical and mechanical properties of rocks including: Uniaxial Compressive Strength (UCS), Brazilian Tensile Strength (BTS), Los Angeles abrasion, quartz content, water absorption percentage, porosity, Schmidt hardness and grain size for all sample measurements were studied after transferring the samples to a rock-mechanics laboratory. Finally, the sawability of the quarried working-faces was evaluated using the PROMETHEE multi-criteria decision-making (MCDM) model according to the physical and mechanical properties. The results of the study indicated that the number 1 and 5 working-faces from the Dehbid and Shayan quarries are the most suitable working-faces in terms of production rate with the maximum recorded production values (4.95 and 3.1 m2 /h), and with net fl ow rates (2.67 and -0.36) respectively.

Petrography and Physicomechanical Characteristics of Iyuku Granite, Southwestern Nigeria

Petrography and physicomechanical characteristics of Iyuku granite from southwestern Nigeria were investigated. Rock and aggregate samples were obtained from five different quarry sites for thin-sectioning and physical and mechanical tests. The rock slides were subjected to petrographic analysis, while the aggregates were tested for the parameters of specific gravity (S.G), water absorption, aggregate impact value (AIV), aggregate crushing value (ACV), Los Angeles abrasion value (LAAV), and flakiness and elongation indices in accordance with the British Standards (B.S), American Standards for Testing Materials (ASTM) and Federal Ministry of Works Standards (FMWS). The petrographic, physical, and mechanical characteristics were described by bar charts and linear graphs. The results revealed that the rocks are of medium to coarse interlocking grains, with no evidence of weathering influences, and quartz content ranging from 17% to 35%. The aggregates showed appreciable high S.G. values, very low water absorption values and low maximum permission limits for AIV, ACV and LAAV when compared with different standards. All the aggregates are adjudged to be generally strong and durable for road construction, but those with higher quartz contents are more preferable. Significant statistical correlations were established among both physical and mechanical tests conducted.

Factors Identification and Conformance of Quality of Cement and Coarse Aggregate used at Gautama Buddha Airport Upgrading Component, Nepal

Quality management system has been challenging in construction of airport project. The objective of study is to assess the factors affecting quality and conformance of Cement and Coarse Aggregate standard used at Construction Site of Gautam Buddha Airport Upgrading Component. This research is based on key informant interview with supervisor and site engineers, questionnaires survey with clients, consultants and contractors who were involved in airport construction projects along with lab test of cement and coarse aggregate of airport construction sites. Statistical tools mean value and relative importance index were used for the ranking of different quality methods. Airport follows specification and standard technical guidelines for the airport construction work. The major factors affecting the quality management in airport construction was Unavailability of competent staff, Low quality drawing and specification and Poor-quality procedure and department for ensuring quality assurance practice Provide training and seminar on quality assurance and Support the setting up of of cube of 3 days, 7 days and 28days is18.8N/mm2 (>16N/mm2), 27.20N/mm2 (>22N/mm2) and 39.40N/mm2 (>33N/mm2) respectively. The average initial setting Time and final setting time of cement is 180 min(>45min) and 351 min(<600min) respectively and average soundness of cement is 2.7mm(<10mm). The test for aggregate, it was found that average Los Angeles Abrasion value of aggregate was 32.8%(<40%), average crushing value of aggregate was 19.88%(<25%), Flakiness index of aggregate found that 19.85%(<25%) and the gradation of aggregate was found that within specification. Quality in airport construction starts from selection of material, inspection, tests employed.