Cement/concrete mixers

Frieficements (83), manufactured in Belgium, are produced as a wet slurry of finely ground slag. When activators such as Pordand cement, lime, or sodium hydroxide are added in a concrete mixer, the slurry sets and hardens to produce concretes with good strength and durabiUty. 

Jahjah [the prior art reference cited by the USPTO] combines the preformed foam into various cement and concrete mixtures wherein known aggregates may optionally be incorporated. The foam is introduced from a reservoir into a concrete mixer containing the cement mix, and, in our opinion, it would be obvious to a technician having ordinary skill in the art to add the foam gradually to the cement mix while it was being mixed, since, as pointed out by the Examiner, conventional cement mixers operate in this fashion. Further, Jahjah obtains uniform dispersion of the foam and produces a multicellular cementitious product not differentiated in this record from that obtained by appellant. 

Alternatively, fly ash may be introduced directly into the fresh concrete mix as a separate component, rather than as a constituent of the cement. To do this, Portland cement, fly ash, and mixing water, together with the aggregate, are mixed in the concrete mixer to produce fly ash concrete. 

Dry mixing— where the fibers are initially mixed with a fine dry aggregate (5 mm), then cement and silica fume added, followed by mixing in a Hobart industrial mixer for about 5 min. The mixing was completed in a concrete mixer to which the coarse gravel aggregate (25 mm) was added [9]. The silica fume helps the dispersion of the carbon fiber and reduces the porosity of the concrete, resulting in an improved bond. 

Portland silica fume cement Addition of silica fume can yield exceptionally high strengths, and cements containing 5-20% silica fume are occasionally produced. However, silica fume is more usually added to Portland cement at the concrete mixer. 

Polymer concrete can be placed by either premix, dry pack or prepack methods. The premix method is similar to the conventional Portland cement concrete mixing and placing. The binder, fine aggregate and coarse aggregate are added to the mixer in that order and mixing is continued until all aggregate particles are thoroughly wetted. Then the material is placed where it is required and consolidated. It is usually recommended that the surface to be treated is primed with the binder before placement. 

The method of producing precast polymer concrete is similar to that of precast Portland cement concrete. The extremely short hardening period of polymer concrete is an obvious advantage over Portland cement concrete. Form removal may be as short as 40 seconds, depending on the type of monomer used [11]. The formwork, vibrators and mixers used in producing polymer concrete precast elements are no different to those used for Portland cement concrete precast elements. Flowever, it should be noted that the formwork should be durable, smooth surfaced and must be able to withstand the heat developed during the exothermic polymerisation process. 

The polymer concrete samples were mixed according to the polymer concrete test method 1.0 of the Society of Plastic Industry (referred to as SPI 1.0) [1-6]. The samples were mixed using a conventional concrete mixer for a period of about 3 min, poured into moulds, vibrated and cured at room temperature according to ASTM C1479 [1-7]. There are no standard tests that are directly applicable to polymer concrete specimens therefore, ASTM standards developed for cement were adopted as applicable guidelines. 

The mix capacity was also varied using the full-size mixer with the same concrete mixes and admixtures. Results are given in Table 3.10 where it will be seen that the effect of batch size is only slight and, in the higher cement content mixes, shows a trend towards higher air content as the capacity of the mixes is approached. 

Generally, polymer latexes used as cement modifiers are not toxic, are safe materials to handle and require no special precautions. However, because they have an excellent adhesion to various materials, even to metals, all the equipment and tools such as mixers, trowels, and vibrators should be washed down or cleaned immediately with water after use. For concrete requiring formwork, it is advisable to use the most effective mold-release agents, e.g., silicone wax or grease [87, 96]. 

Except for the CMUs which were produced in an industrial block plant, the batches were completed following the same procedure. Before starting a typical concrete batch, the water, sand and pea gravel were adjusted for moisture content. The two aggregates and the plastic filler were introduced into the mixer and mixed for approximately 30 seconds. The cement and two-thirds of the total water were added and the drum was rotated for 2 minutes more. The rest of the water was added within the next 30 seconds. After two minutes the drum was stopped, and the slump test was performed. The drum was then scraped to loosen any material not previously mixed. It was restarted and rotated... 

The treatment zones consisted of curtains of zero-valent iron suspended in a kaolin clay slurry. The clay, water, and iron filings were mixed in a cement mixer and were delivered to the installation equipment using a standard concrete pump. The slurry contained 50% iron by weight. The iron filings remain in place after operations and will continue to treat residual TCE in the soil long after the DC power is turned off. This prevents any rebound issues associated with some extractive remediation systems for low-permeability or heterogeneous sites. 

Through this study, dry mortar system, in which mortar with carbon fiber was produced at site by adding only water, was created. All materials but water, such as cement, carbon fibers, fine aggregate and admixture, were mixed at a factory. Mortar with carbon fiber can get at site with a usual mortar mixer. Mix proportion and properties are shown in Table 5. This dry mix system are being used as a finishing material of block, wooden surface and concrete. 

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