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.
Experimental Research and Application of Super-Retarding Mortar
In scores of experiments indicates that the super-retarding mortar, keeping plasticity long-term, can make cement setting and hardening at a slower speed through chemical additive. Based on large numbers of orthogonal tests and theoretical analyses, the super-retarding mortar which satisfies the demands of actual engineering was developed successfully in present paper. And it is consist of cement, sand, water and composite retarder blended in an appropriate rate. From 0°C to 40°C, setting time can be adjusted from 1 day to 22 days in the light of to the engineering requirements, and after condensation, it begins to harden gradually and ends with the compression strengthen over 30MPa. Experiments were employed to test the influences of accession amounts of composite retarder dosage on setting time and compression strengthen of super-retarding mortar. Besides, the retarding mechanism was studied, and the super-retarding mortar was applied to experimental models. The results show the super-retarding mortar can be applied to the actual engineering, and it can be treated as the theoretical reference for the actual project application of the new prestressed concrete system.
Rapid determination of the effectiveness of insect resistant packaging
A technique was developed to evaluate the usefulness of odour barriers and to determine the effect of package content in consumer size packages on resistance to infestation by insects. Female Plodia interpunctella (Hubner) could distinguish sealed packets containing food from non-food items as a suitable site for oviposition. Utilization ofthis technique will reduce the time needed to evaluate new materials for use in insect resistant packaging.