Aims and Scope
Influence of Heterogeneity, Typology, and Contaminants of Recycled Aggregates on the Properties of ConcreteGilberto A. da Silva Neto, João P. V. de Oliveira, Pedro V. Salles, Raphael T. de Vasconcelos Barros, Maria T. Paulino, White J. dos Santos
The depletion of raw material resources, the preservation of the environment, and the need to compensate economic imbalances drive research efforts regarding the application of Construction and Demolition Waste (CDW) in concretes.
This paper aimed to assess the influence of the heterogeneity, typology, and presence of contaminants of CDW (collected in different seasons and locations) on the mechanical properties and durability of concretes.
Characterization procedures were performed for the aggregates (visual quantification and physical properties of the constituents), and for the concretes (compressive strength, splitting tensile strength test, modulus of elasticity, water absorption, porosity, electrical resistivity, carbonation depth, and digital microscopy). The replacement rate of natural aggregate for CDWA was of 20% in three different particle sizes: sand, gravel 0, and gravel 1.
The characteristics of the samples of CDW were very variable, influenced by the season and location of collection. The presence of materials with elevated porosity (ceramics, mortars) was observed in some samples and required increases in mixing water volume to keep the concretes’ consistency. A wide variation in mechanical properties caused by the CDWA constituents was also observed. Regarding the durability of the concretes, it was proven the greatest sensibility of this property to contaminants, thus requiring the removal of deleterious materials to using CDWA in structural concretes in order to avoid the formation of vesicles and guaranteeing their life span.
The heterogeneity, typology and contaminant content significantly influence the analyzed properties. Besides, the segregation of waste at source makes the use of CDWA feasible in concretes.
December 31, 2020
- December 21, 2020
- November 27, 2020
- October 08, 2020
- August 24, 2020
- August 19, 2020
- June 29, 2020
Uplift resistance of deep foundations or piles is a critical factor for deep foundation design in several civil engineering applications such as electric transmission towers, communication towers and wind power generators. Therefore, the behavior of the pile under uplift load, together with its influential parameters, should be studied to provide a proper design.
The aim of this study was to identify the effects of pile geometry, including diameter and embedment depth on the Maximum Uplift Resistance (MUR) of the small-scale piles.
To achieve the aims of this study, a total of nine laboratory experiments having various pile diameters (i.e. 9 mm, 12 mm and 15 mm) and embedment depths (i.e., 10 cm, 15 cm and 20 cm) were planned, designed and conducted.
Generally, the results indicated that both diameter and embedment depth have a significant effect on the MUR of piles. The values of the MUR of piles were increased by increasing the pile diameters in all conducted tests. Furthermore, a significant increase in the MUR results was observed when the embedment depths are increased from 10 cm to 20 cm. Moreover, in all cases, small-scale piles were failed in embedment depths ranging from 5 mm to 10 mm.
It was concluded that pile geometry has a deep impact on the MUR of the piles. Future research can be done to investigate the effects of other influential factors on the MUR.
December 31, 2019
- August 30, 2019
- March 28, 2019
- August 30, 2019
- January 31, 2019
- November 23, 2018
- November 30, 2017