scholarly journals Effect of Admixtures on Concrete and Superplasticizers on Cementitious Material

Author(s):  
Mehak Bashir

Abstract: Use of chemical and mineral admixtures have proved beneficial in improving quality, workability and have enhanced finish ability of concrete. They also help in maintaining the concrete during its important stages such as mixing, transporting, placing, curing and also in adverse weather conditions. Superplasticizers are super water reducers that allow 15-20% water reducion thereby increasing the workability without any change in the composition of mix.The reduction in water and cement reduces creep, shrinkage and heat of hydration. In this paper effect of different chemical and mineral admixture was studied along with sand to aggregate volume ratio ,cement content and water were analysed by preparing different concrete mixtures using water reducers and superplasticizers. A specimen of 200mm and 300mm was prepared and tested for compressive strength, split tensile strength and young's modulus. Slump test was also performed at 15 min interval. Also superplasticizers (TJ III , LIGNIN-SULPHONATE-based and NAPHTHALENE-SULPHONATE-based) were taken and their effect on the heat of hydration and induction period of cementitious material (portland cement) was studied. Keywords: admixture, workability, superplasticizer, water cement ratio, heat of hydration.

2021 ◽  
Vol 2 (1) ◽  
pp. 46-62
Author(s):  
Santiago Iglesias-Baniela ◽  
Juan Vinagre-Ríos ◽  
José M. Pérez-Canosa

It is a well-known fact that the 1989 Exxon Valdez disaster caused the escort towing of laden tankers in many coastal areas of the world to become compulsory. In order to implement a new type of escort towing, specially designed to be employed in very adverse weather conditions, considerable changes in the hull form of escort tugs had to be made to improve their stability and performance. Since traditional winch and ropes technologies were only effective in calm waters, tugs had to be fitted with new devices. These improvements allowed the remodeled tugs to counterbalance the strong forces generated by the maneuvers in open waters. The aim of this paper is to perform a comprehensive literature review of the new high-performance automatic dynamic winches. Furthermore, a thorough analysis of the best available technologies regarding towline, essential to properly exploit the new winches, will be carried out. Through this review, the way in which the escort towing industry has faced this technological challenge is shown.


2018 ◽  
Vol 163 ◽  
pp. 502-517 ◽  
Author(s):  
N.P. Ventikos ◽  
A.D. Papanikolaou ◽  
K. Louzis ◽  
A. Koimtzoglou

Transfers ◽  
2013 ◽  
Vol 3 (3) ◽  
pp. 79-98 ◽  
Author(s):  
Shahnaz Huq-Hussain ◽  
Umme Habiba

This article examines the travel behavior of middle-class women in Dhaka, the capital city of Bangladesh and one of the world's largest and most densely populated cities. In particular, we focus on women's use of non-motorized rickshaws to understand the constraints on mobility for women in Dhaka. Primary research, in the form of an empirical study that surveyed women in six neighborhoods of Dhaka, underpins our findings. Our quantitative and qualitative data presents a detailed picture of women's mobility through the city. We argue that although over 75 percent of women surveyed chose the rickshaw as their main vehicle for travel, they did so within a complex framework of limited transport options. Women's mobility patterns have been further complicated by government action to decrease congestion by banning rickshaws from major roads in the city. Our article highlights the constraints on mobility that middle-class women in Dhaka face including inadequate services, poorly maintained roads, adverse weather conditions, safety and security issues, and the difficulty of confronting traditional views of women in public arenas.


2021 ◽  
Vol 7 (3) ◽  
pp. 52
Author(s):  
Yazan Hamzeh ◽  
Samir A. Rawashdeh

Research on the effect of adverse weather conditions on the performance of vision-based algorithms for automotive tasks has had significant interest. It is generally accepted that adverse weather conditions reduce the quality of captured images and have a detrimental effect on the performance of algorithms that rely on these images. Rain is a common and significant source of image quality degradation. Adherent rain on a vehicle’s windshield in the camera’s field of view causes distortion that affects a wide range of essential automotive perception tasks, such as object recognition, traffic sign recognition, localization, mapping, and other advanced driver assist systems (ADAS) and self-driving features. As rain is a common occurrence and as these systems are safety-critical, algorithm reliability in the presence of rain and potential countermeasures must be well understood. This survey paper describes the main techniques for detecting and removing adherent raindrops from images that accumulate on the protective cover of cameras.


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