Concrete Manufacturing

The concrete should be used as efficient as possible. Nowadays researches efforts are continuously looking for new, better and efficient construction method. Various theories related to the analysis of structural elements reduced the self-weight of element for a given load- carrying capacity. Structural material optimization can reduce the dead load which reduce the contribution of seismic effect in high rise structures and also very good at the vibration dampers and heat isolation. According to the natural behaviour of the concrete, it is strong in compression and weak in tension.

13) The 50 (MWCO) Dialysis Membrane was placed in the center of the left and the right beaker. 14) Nine millimolar of Na⁺Cl⁻ is poured into the left beaker. 15) Deionized Water is placed in the right beaker. 16) A sixty-minute timer was started to see how the 9 Na⁺Cl⁻ (mM) solvent diffuses through the 50 (MWCO) Dialysis Membrane. 17) The outcome was cataloged.

Standard Preparation: 100 mg of standard ascorbic acid was weighed precisely and transferred to a 100 ml volumetric flask, added 70 ml of 0.5% sodium metabisulphite and dissolved by shaking. The volume was made up to the mark with 0.5% sodium metabisulphite for getting a concentration of 1 mg/ml. 2 ml of this solution was taken into another 100 ml volumetric flask and made the volume up to the mark with 0.5% sodium metabisulphite which resulted in concentration of 0.02 mg/ml. The solution was filtered through 0.45 µ nylon syringe filter. Sample Preparation: 2.5 g of sample was weighed accurately and transferred to a 100 ml volumetric flask.

In practice, this is often not the case, and instead, fractures may take place in the bond material, the substrate, or both and may extend beyond the initial bonded area. What is actually being measured is the fracture force of a bonded system for a particular method of load application and should only cautiously be interpreted as bond strength [12]Hence, the failure modes of e.g. Glass ionomer cement [12],[13] and Biodentine [14],[15] to dentine were largely cohesive within the cement rather than at the interface. Therefore, the rigidity of the material has a significant influence on the interpretation of bond strength

3.5.2. CONCRETE MANUFACTURE This is a process that describes the making of fresh concrete cubes and testing for compressive strength. The test cubes had a nominal size of 150mm and maximum aggregate size of 20mm. Making test cubes from fresh concrete procedure was in accordance to BS 1881: Part 108: 1983 (cited in Ministry of works, 2000). EQUIPMENT USED • Moulds of cast iron or steel, with removable base plate were prepared.

Table 4.3 shows the density test in 1.0wt.%, 1.5wt.% and 2.0wt.% of magnesium doped calcium phosphate pellets at 1000ºC sintering temperature for five samples. The mean density of different concentration are measured based on the average of five samples.

3.6.4 Assay of Catalase (CAT) Catalase activity was assayed by measuring the inhibition rate of Hydrogen peroxide at 240nm according to the method described by Luck (1974). For this assay, • A 20% homogenate of the leaf extracts of different plants was prepared in phosphate buffer, 0.067 M (pH 7.0). The homogenate was then centrifuged. The supernatant was then used as enzyme extract. • Hydrogen peroxide (H2O2, 2mM) in phosphate buffer (3.0ml) was taken in an experimental cuvette, followed by the rapid addition of 40μl of enzyme extract and mixed thoroughly.

For the nominal water volume of 5ml, apparent mass of water for Trial 1, Trial 2 and Trial 3 are 5.064g, 4.976g and 4.945g respectively. The true mass of water of each trial are 5.070g, 4.982g and 4.951g respectively. Since all three trials have the same temperature, the density is 0.997296g/ml. After calculation, the actual volume of water being transferred for Trial 1 is 5.084ml, for Trial 2 is 4.996ml and for Trial 3 is 4.964ml. The average of water transferred is

Plastic shrinkage crack may not affect the strength of structure but will ruin the appearance of the structure and the crack to full depth may allow water to penetrate it. Figure 9. Plastic Shrinkage Crack Figure 9[10] is a representation of plastic shrinkage crack where crack propagation is highly evident. There are several ways to minimize this crack such as in hot weather, lower the temperature of the fresh concrete by using chilled mixing water or replacing some of this water with crushed ice. Covering the concreted area to avoid excess evaporation or proper curing can help reduce this crack formation.

Because this lime is fixed in the soil and is not available for other reactions, the process has been referred to as lime fixation (Hilt and Davidson, 1960). The lime fixation point corresponds with the point where further addition of lime does not bring about further changes in the plastic limit. This therefore is the optimum addition of lime needed for maximum modification of the soil. Beyond this point excess lime can only produce cementitious compounds, which bind the flocculated particles and develop extra strength (Al-Rawas et al. 2002; Bell, 1996; Mathew and Rao, 1997).