Mixes designs

Although the mix consists mainly of the polymer dispersion, it is usual to use several additives to achieve the desired performance. A typical mix for producing a glove is shown in Tab. 15-1 and the various additives are discussed below. 

Talx 15-1 Typical latex-based formulation for dipped gloves. 

Antioxidant is normally included in the latex by the polymer manufacturer, but if not it can be added to the mix by the compounder. 

The alkali (in the example of Tab. 15-1, potassium hydroxide) is normally added to 

The zinc oxide also reduces the colloidal stabihty of the mix and so influences the amount deposited on the former during coagulant dipping. 

The concrete composition and the constituent materials for designed or prescribed concrete are chosen to satisfy the requirements specified for fresh and hardened concrete, taking into account the production process and the intended method of execution of concrete works. A single mix has to be defined that is able to satisfy all the requirements. The procedure used for selection of a concrete mix (type and proportion of cement, water, aggregate, and admixtures) is called the mix design. Several procedures for mix design can be found in the technical literature, which are based on empirical correlations that associate the requirements for concrete to different parameters of its composition, such as the w/c ratio, the water content, etc. [4,10-12]. Some of these parameters are associated with more than one of the requirements. This is the case for the wjc ratio. 

Once the w/c ratio has been found, the dosage of cement, water and aggregates has to be calculated. The water content (kg/m of concrete) can be estimated on the basis of the consistency class, the properties of the aggregate, and the use of a plasticizer. For instance Table 12.2 shows the water content suggested by the ACI Manual of concrete practice [4]. 

The procedure of mix design should finish with a trial mix (or initial test) in order to check, before the production starts, if the concrete meets all the specified requirements in the fresh and hardened states. 

---

Mix Design Methods for Asphalt Concrete MS-2), The Asphalt Institute, 1974. 

Attempts have also been made to carry out surface modifications of the aggregate to enhance interactions with the asphalt (135) and other workers have made attempts to measure or predict the strength and type of asphalt—aggregate bonds (136,137). However, it must also be remembered that mix design parameters play an important role in determining the performance of asphalt—aggregate mixes (138—142). 

Mix Design Methods forMsphaltic Concrete, Manual Series No. 2, The Asphalt Institute, CoUege Park, Md., 1974. 

For an all-steel heat exchanger AAith mixed design pressures the total extra for pressure is 0.7 X pressure extra on shell side plus 0.3 X pressure extra tube side. 

Mottel and Colvin (U.S. AEC DP-254, 1957). Continuous heat transfer between kerosine and water vessel of Pump-Mix design (Fig. 15-28). 

Nozzle-Mix Burners The most widely used industrial gas burners are of the nozzle-mix type. The air and fuel gas are separated until they are rapidly mixed and reacted after leaving the ports. Figure 27-32c, d, e,f, h shows some examples of the variety of nozzle-mix designs in use. These burners allow a wide range of fuel-air ratios, a wide vari-... 

Asphalt Institute recommended cold mix method Resistance to plastic flow of bituminous mixtures using Marshall Apparatus Immersion—Marshall method Immersion—Marshall method Superpave mix design... 

Asphalt concrete is properly proportioned to resist the potentially damaging effects in the road. Asphalt concrete paving mixtures should be evaluated for the following properties stability, flow, air voids, stripping resistance, resilient modulus, compacted density, and unit weight. Table 4.18 provides a list of standard laboratory tests that are presently used to evaluate the mix design or expected performance of fresh and hardened asphalt concrete. 

Carbon mixes, designing, 12 729-730 Carbon molecular sieves... 

Develop mix design Determine end use Excavate and produce product Confirm effectiveness Construct end use (i.e., road base, pavement, etc.)... 

The mix design was as follows strength 30 MPa, cement OPC 280 kg. fly ash 120kg, water 140kg, stone, 19mm 1110kg, stand 245 kg, crushed dust 585kg,W/C ratio 0.5. 

The other members of the water-reducing admixture group possess some other function which could not be obtained by mix design considerations. 

When a normal, accelerating, or retarding water-reducing admixture is utilized to increase the workability of a concrete mix by direct addition, it would be reasonable to assume that the extent of the effect would be markedly affected by changes in mix design parameters such as cement content, aggregate size, shape and grading, and the water-cement ratio. A study of many hundreds of results, however, indicates that this is not the case and Fig. 

This independence of efficiency in relation to mix design parameters is only true with regard to workability increases where a concurrent change in water-cement ratio is made, a number of variables must be considered and this will be discussed later. 

The most widely used application of water-reducing admixtures is to allow reductions in the water-cement ratio whilst maintaining the initial workability in comparison to a similar concrete containing no admixture. This, in turn, allows the attainment of a required strength at lower cement content to effect economies in mix design. 

Table 1.17 summarizes published data for a variety of water-reducing admixtures in a range of mix designs. 

It is clearly not the purpose of this book to give a guide to the principles of good mix design, which is already catered for by a number of excellent books and reviews [79-82] but rather to set down a few points which are relevant to the use of water-reducing admixtures. 

Economies in mix design are effected by reducing the cement content whilst maintaining the same water-cement ratio. In view of the reduction of paste volume, conflicting recommendation are made of how this should be compensated for. The following is a guide [84] ... 

---