An Experimental Study of Effects of Superplasticizer on Fresh and Hardened Properties of Concrete
This paper presents the results of an experimental research on the workability and compressive strength of ordinary and standard concrete. Superplasticizers are commonly known as High Range Water Reducers (HRWRs) because it permits low water cement ratio as well as the workability also affected. In this paper the properties of concrete mixtures with three different dosages of superplasticizers SNF have been investigated. In this experimental programme superplasticizer Sikament®170(SWP) of basically modified naphthalene/melamine formaldehyde sulphonate dispersion and having brown liquid confirming to IS: 91031999 & IS: 2645, ASTM C 494/C494M, Type F has been used. The properties investigated are workability on the fresh state and compressive strength on the hardened state of concrete by using three mixes with three superplasticizer dosages (0.2%, 0.4% and 0.6%) is used. Various concrete mixes (M-20, M-30 and M-40) are design by IS 10262:2009, Concrete Mix Proportioning Guidelines. Compressive strength at 7 and 28 days was also determined. The graphs between different percentage of superplasticizers with W/C ratio and compressive strength are plotted. Overall 72 specimens (concrete cube) with the dimension of 150 mm x 150 mm x 150 mm were fabricated at laboratory.
Effect of superplasticizer dosages on compressive strength of self compacting concrete
Self-compacting concrete has to fulfil contradictory requirements of high flowing ability when it is being cast and high viscosity when it is at rest, in order to prevent segregation and bleeding. These requirements make the use of mineral and chemical admixtures essential for self-compacting concrete. High flowing ability is achieved using superplasticizers, while stability against segregation is achieved either by using a large quantity of fine materials, or by using appropriate viscosity modifying agents. This paper presents the results of an experimental research carried out to investigate the effect of dosages of superplasticizer on compressive strength of self- compacting concrete.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.