Cement Stone

Small amounts of pyridine bases increase the corrosion resistance of cement stone without any associated loss of strength [1016]. The use of nitrilo-trimethyl phosphonic acid and an adduct between hexamethylene tetramine and chlorinated propene or butene improves the adhesion to the metal, hardening times, mobility, and strength [ 1770]. The latter adducts are further claimed to be useful as additives in cementing oil and gas wells in salt-bearing strata [1768]. 

Isobutanol is used as an alcohol component, to increase strength of produced cement stone. It should be noted, however, that gallium and indium are precious and better used in the nonferrous metal industries. 

R. A. Allakhverdiev, B. Khydyrkuliev, and N. V. Reznikov. Plugging solution for repairing oil and gas wells-contains plugging Portland cement, isobutanol, water and liquid metal alloy of gallium, indium and tin, to increase strength of cement stone. Patent SU 1802082-A, 1993. 

The Babylonians and Assyrians cemented stone slabs as well as bricks with bitumen (which is sometimes also referred to as asphalt), a mixture of a black or brown natural organic material with a pitchy luster and comminuted mineral. Bitumen is a thermoplastic solid material when heated above 50°C, it softens and becomes a thick, viscous liquid that reverts to a solid on cooling. It is composed of a natural mixture of hydrocarbons (organic substances composed of carbon, hydrogen, and oxygen) that occurs in natural... 

Electric Utility Development Operation Construction, Heavy Civil Engineering Cement, Stone Asphalt Production Road Bridge Holdings Water Utility... 

Concrete is an excellent example of a more modern composite, being made up of cement, stones, and/or sand. It is often reinforced with steel rods. 

It should be emphasized that the concept of linear fracture mechanics can be applied only to materials with fine structure, such as a cement stone or fine-grained concrete, that is, to linear-elastic bodies. For such bodies, a condition of self-similarity for the prefracture zone exists... 

Film coatings are widely applied in forming concrete and reinforced concrete structures to accelerate concrete hardening and reduce crack appearance at setting. The film prevents evaporation of the water contained in the concrete, promotes hydration of the cement, and thus provides reliable contact of the cement stone and filler. It promotes an increase in concrete strength up of up to 30%, reduces damage and time of processing, and restricts moisture absorption. 

Materials (kg/m ) Cement Stone Sand Silica Sand Silica Fume Crushed Quartz Steel Fiber Super- plasticizer Total Water... 

Keywords shrinkage, PCC, PCM, polymer modified, cement stone, adhesive bond, longitudinal change behaviour, shrinkage stress, porosity... 

Determination of shrinkage on polymer-modified cement stones... 

After the investigations on PCCs in modified shrinkage channels had not led to the expected results, the aim was to verify the gained findings by means of experiments on polymer-modified cement stones (Fig. 3). CEM I - cement stone recipes were used. The water requirement of the stone granulation as to its w/c ratio was taken into account. 

Figure 4 Shrinkage of cement stone, with polymer 1 modified cement stone (ZSl) and with polymer 2 modified cement stone (ZS2)...

Experiments on the longitudinal change behaviour of polymer-modified cement stones on the adhesive bond... 

In the experiments carried out so far, it was shown that the longitudinal change behaviour of mortars is negatively influenced by polymer modification. In order to draw conclusions what kind of effect this has as far as cohesion in the PCCs is concerned, model tests were carried out on stone samples which were coated on both sides with modified cement paste. In preliminary works before, the development of the dynamic E-modulus as well as of the tensile strength of the cement stones had been investigated. 

The result shows that the determined values for the tensile adhesion strength are extremely low. The tensile adhesion strengths of all cement stone samples are significantly lower than the tensile strengths of both stones and the cement stones themselves. When judging the fracture pattern it could be observed that above all it had come to a cohesion failure of the stones. The examination of the test pieces before test start showed a pre-damage on all samples which had not been there on the stone slices after demoulding (Fig. 7). 

The resulting values are strongly abstracted and can only be compared with caution. Unconsidered remains the fact that a major part of the stresses is brought down by plastic deformations of the cement stone, or stresses are reduced by crack formation. Furthermore it has to be said that only the dynamic E-modulus was available for calculations. It differs from the static E-modulus which is us-ally taken for the stress determination. For these reasons the results from the polymer-modified cement stones were related to those from the not modified ones. In doing so, it becomes possible to make statements by trend as to the influence of polymer modifications. 

The influence on the shrinkage caused by the polymers is only visible some days after mixing. This could be proven for the mortar as well as for the cement stone by means of experiments in modified shrinkage channels. 

Soroka, I., and Sereda, P. J., The Structure of Cement Stone and the Use of Compacts as Structural Models, Proc. 5 Int Symp. Chem. Cement, Tokyo, 111 67-72, (1968)... 

Hughes, D. C., Sugden, D. B., JagMn, D., and Mucha, D., Calcination of Roman Cement A Pilot Study Using Cement Stones from Whitby, submitted to Constr. Build. Mater.. 

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