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 SUPERPLASTICIZERS ON WORKABILITY AND STRENGTH OF CONCRETE
It has long been a concrete technologist’s dream to discover method of making concrete at the lowest possible water/cement ratio while maintaining a high workability. To a considerable extent this dream has been fulfilled with the advent of superplasticizers. Have indeed added a new dimension to the application of admixtures with regards to production of high strength and flowing concretes. It is now possible to produce concrete with compressive strength of the order of 13000 psi (90 Mpa). In addition, these are also suitable for use with other cementations materials like fly ash and blast furnace slag. In the wake of energy conservation policy and diminishing supplies of high quality raw materials, there is a need to use marginal quality cements and aggregates for the production of concrete. In such instances the use of superplasticizers permits the production of concrete at low water/ cement ratios. Thus many waste materials of today become the useful by products of tomorrow. It is the particular role of superplasticizers, which is very importance for us here in Pakistan, because of our poor economy and less developed industrial base. Besides, the addition of superplasticizers to produces concrete with less cement but normal strength and workability is another application, which has received more attention. In this research programme two types of superplasticizers(Rheobuild 1100,Rheobuild561M) of synthetic polymer base confirming to ASTM C-494 type A&F and ASTM type B,D&G respectively has been used. Three nominal ratios of 1:1:2, 1:1.5:3 and 1:2:4 were used for mix proportioning of concrete constituents by weight. The water cement ratio was maintained as 0.50, 0.55 and 0.60 to study the effect of these SP on various properties of concrete. The dosage of superplasticizers was adopted as constant @ 0.80% by the weight of cement. To study the effects of superplasticizers the experiments have been divided into three series namely workability series, water reduction series and cement saving series. The result have shown substantial improvement in the properties of concrete after use of the superplsasticizers.The Rheobuild 561M high range water reducer,superplasticizer has given more promising results as compared to Rheobuild1100.
Thermodynamics on the Carbochlorination of Titanium-bearing Ores
The equilibrium compositions of the multi-component, multi-phase and multi-reaction system of carbochlorination of titanium-bearing ores are calculated with HSC, a computational chemistry software. The thermodynamic equilibrium calculation of the reaction system shows that a complete conversion of titanium-bearing ores is feasible at a temperature near 200oC. At temperatures ranging from 800 to 1600oC, the products of the reaction system are all in gaseous phase. Thermodynamic analysis accords with the industrial practice. The simulated results provide reasonable scientific basis for improving suitable technological conditions of the carbochlorination reduction.