Attempts to study the effect of vibration of fresh concrete have mainly been based on visual observation of, for example the radius of influence of the insertion vibrator, or the rate of flow of concrete down a tube when vibration is applied. The reason for this has been the difficulty of measuring the sinusoidal wave form created by mechanical vibrators. Advances in electronic equipment have made devices for measuring this wave form commercially available, and they have therefore been used in this research project to gain a better understanding of the consolidation process. The amplitude of the sinusoidal signal was calculated from the acceleration measured at distances up to 250mm from the surface of the insertion vibrator. Preliminary tests indicate that the amplitude of the vibratory wave decays exponentially with distance. The damping coefficient is greater for superplasticized high-strength concrete mixtures with low W/C than it is for normal-strength concretes. An attempt was made to relate the damping coefficients to the rheological properties, yield (g) and plastic viscosity (h) values determined from tests carried out with Tattersall's two point test apparatus. Both the yield (g) and plastic viscosity (h) values were found to increase by decreasing the W/C, despite the concrete having an equal slump of 150 mm. This shows that the slump values obtained by the use of high dosages of superplasticizers, as is the case with low W/C, are not directly comparable to those resulting from high water contents, with respect to the rheological behavior of concrete.

High-performance concrete (HPC) has been studied extensively at many research centres, because of its increasing use in reinforced concrete buildings. Since HPC is a brittle material, studies have been done to increase its ductility. Increases in longitudinal and /or transverse steel ratios can improve the ductility of HPC elements. The addition of fibres also increases the deformability and thus the ductility. Hence, the transverse steel ratio can be reduced by using fibres. This paper presents a study of axially loaded columns made with high-performance concrete containing steel fibres. The average compressive strength of the concrete was 80 Mpa. The volumetric ratios of fibres were: .25%; .50% and 1.00%, and the stirrup ratios were .55% and .82%. The longitudinal steel ratio was the same for all columns tests, the W/C was .37, 10% silica fume was added and it was also necessary to use about 3% superplasticizer to improve workability. A comparison was made between the results for columns in high-strength concrete with and without fibres. It was observed that only the cross-sectional core effectively contributed to the load capacity of the columns.

This paper give some results of flowing and high strength concretes using type F fly ash (FA) and naphthalene based superplasticizer (SP). In series S.Sp was used only to produce flowing concrete and in series H was used to reduce W/C and to cause the concrete to flow. In each studied series the portland cement content was maintained fixed of 250 kg/m3. Fly ash was added as a percentage of the normal portland cement from 10% up to 150%. For reference series a .8 W/C was used, and for series S. 200 liters of water was used to attain a nominal consistency of 60.0 cm DIN. For reference series H a reduction of 35% of mixing water of series S was used (70 L). To find the maximum amount of FA and SP dosage in series S, SP admixture was used to obtain the reference consistency of 60.0 cm DIN. In series H where the admixture was used as high-range water-reducing-retardant admixture (HRWRRA) in large dosages, the concrete becomes very cohesive and significant slump loss was noted. When superplasticizer-retardant admixture (SPRA) was used as HRWRRA to produce flowing concrete under established conditions, it was possible to obtain a very significant compressive strength gain at 56 days, which was the upper limit of the age covered in this study. An increment of 160% (from 25 to 65 Mpa) at 56 days was attained for series H in relation to the reference mixture without FA and SP. To obtain high strength concretes using high volumes of fly ash, it is essential to use SP admixture.

A "realistic" structural computer simulation system, SPACE, has been developed to assess the characteristics of dense random packings of particles in opaque materials like concrete. The paper presents a short introduction to the system, thereby only dealing with the essential design features. Nest, some applications to particle packing problems will be demonstrated, in which use is made of the simulation system. It will be shown that it can be a useful tool to support or even to evaluate experimental studies. But most of all, it will be shown that it can offer information on structural details that can not be obtained in another way, or only at the expense of considerably more effort. These structural details provide insight into complicated assessed that interface discontinuities in a particulate composite will extend much further into the interior of the material body than suggested by density or porosity measurements near such interfaces.

This paper discusses a new method for the determination of the optimum W/C plus FA for maximum compaction of no slump concrete made with high volumes of fly ash. It explores the effect of fly ash fineness and particularly, carbon content on the explores the effect of fly ash fineness an particularly, carbon content on the compressive strength of the mixtures made with 50% and 70% replacement of normal portland cement with fly ash. By using an appropriate surfactant the no slump concrete mixtures are rendered workable and suitable for structural applications. The strength attained at 28 days is 60 Mpa or more, and therefore these mixtures are considered to yield high-strength concrete. The performance of the high-volume fly ash concrete is assessed in terms of abrasion and fatigue resistance that are the most appropriate performance indicators for concrete that will be used for the construction of pavements.