Self-Levelling Concrete

The use of self-consolidating, self-leveling concrete was chosen due to the height of concrete placement and dense placement of reinforcing steel. Injection ports in the side walls of the forming system allowed the concrete to be pumped into place. Many ports within the form system allowed for the concrete to be placed relatively close to its final location, and kept the horizontal travel distance of the concrete to a minimum. 

Self-compacting concretes (SCC) and self-levelling concretes (SLC)... 

Rols, S., Ambroise, J., Pera, J. (1999) Effects of different viscosity agents on the properties of self-levelling concrete . Cement and Concrete Research, 29 261-66. 

The general term workability is used to express these overall properties of the fresh mix and is applied to all kinds of concrete. Special concretes that do not require any additional operations for placing and compacting, so-called self-compacting concretes (SCC) and self-levelling concretes (SLC)... 

Natural polymers usually produce very complex degradation product patterns, which make the identification of the products difficult. Casein, used in self-levelling concrete. 

J. Ambroise, S. Rols and J. Pera, Properties of self-levelling concrete reinforced by steel fibres , in H.W. Reinhardt and A.E. Naaman (eds) Mg/ Performanoe Fiber Reinforoed Cement Composites (HPFRCC3), RILEM Proceedings PR06, RILEM Publications, Bagneux, 1999, pp. 9-17. 

LMC is used in underwater concrete for both new construction and repair. The important requirements to obtain antiwashout capability, such as segregation resistance, flowability, self-leveling characteristics and lower bleeding are provided by the addition of viscosity-enhancing polymeric admixtures at polymer-cement ratios of 0.2-2.0%. These admixtures are water-soluble polymers, and classified under two groups, viz., cellulose types such as methyl cellulose and hydroxy ethyl cellulose and polyacrylamide types such as polyacrylamide and polyacrylamide-sodium acrylate [101]. 

With the advent of high-performance concrete and the development of third-generation (mostly acrylic polymer-based) superplasticizers which provide significantly higher water reduction at flowable consistencies, this demarcation has blurred. Through the use of a mixture of admixtures it is now possible to obtain highly durable low water-cement ratio concretes that are nearly self-leveling and yet quite cohesive. 

Often it is difficult to adjust the mixture proportions to achieve desired design parameters for all properties of concrete. Consequently the properties of colloidal underwater concrete are controlled by the addition of three chemical admixtures. Minimum water-cement ratios range from 0.36 to 0.40. Cement and fine-aggregate contents are usually higher than corresponding mixes placed on land, and silica fume may be used in conjunction with a superplasticizer or conventional water reducers to reduce segregation. The key to a non-dispersible concrete with self-leveling characteristics is the successful optimization of the VEA with the superplasticizer used to increase the slump. 

Concretes containing VEAs have consistencies that are structured while static but become highly flowable, with self-leveling characteristics, when work is imparted to it. Data presented in Fig. 7.28 show that medium-strength concretes with equal slumps perform very differently in the washout test. This indicates that the slump test does not correlate to washout... 

These are used to produce prepackaged products such as decorative wall coatings, ceramic tile adhesives, self-leveling floor overlays and patching mortars for concrete structures. On site, addition of the product manufacturers specified amount of water produces a material with the desired properties. During the wet mixing, the... 

Polymeric overlays are used on concrete pavements to protect them from dust, excessive wear, cracking, crazing, spalling and to provide an attractive appearance. These materials are applied on concrete pavements in the form of screeds, self-levelling material or floor coatings. Epoxies, polyurethanes and acrylics are commonly used, epoxies being the most commonly chosen. Table 1.4 gives the suitability of these materials for different environments. 

Self-levelling polyurethane sealants are used to seal horizontal movement joints and construction joints in a variety of materials subject to light traffic such as concrete pavements (Figure 4.4), access roads, yards, parking areas, between rails and metal enclosures and around equipment and machinery. 

Floor topping A polymeric material applied on concrete floors for a specific reason. Screed floorings and self-levelling floors are included in this category. 

Polyurea seals are 100% solid, with high elongation self-levelling elastomers. They are completely VOC free, used in horizontal saw or preformed joints on concrete or asphalt. 

Numerous and diverse products incorporate casein in their formulations. These include dish-washing liquids, cosmetics, lightweight concrete, gypsum wallboards, pesticide sprays, water purifiers, self-levelling underlayments, and so on [12-14]. 

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