In this study, the rheology and early reaction process of sodium hydroxide-activated ground granulated blast furnace slag (GGBFS) were investigated. Test results showed a strong relationship between Vicat initial setting time ultrasonic pulse wave for NaOH activated mixtures identifying characteristic points or inflection in curves reaching specific value velocity. The pastes determined by calo...

Spatial variability of concrete is an important characteristic, which qualifies the non-homogeneity of concrete properties within structural components. Assessing it can be of great interest for damaged areas localization and for reliability analysis of structures. A two-stage experimental program was carried out using non-destructive testing (NDT) on laboratory concrete slabs in outdoor enviro...

The setting and hardening process of concrete is considered to be the most critical time period during the life of a concrete structure. Previous research has been conducted on an ultrasonic wave reflection method that utilizes a steel plate embedded in the concrete to measure the reflection loss of shear waves at the steel-concrete interface. The reflection loss has been shown to have a linear...

Focusing an ultrasonic surface or bulk wave to a point can maximise the amount of ultrasonic energy at a point and increase the sensitivity of a measurement. Using noncontact ultrasonic methods we focus an ultrasonic wave pulse on or in a sample. Focusing can be achieved by using a shaped source or by the surface profile of the sample itself. Experiments and modelling confirm the known result t...

Gypsum is a mineral belonging to the group of sulfates, i.e., sulfuric acid, which often found in Earth's crust. In this paper, two main types gypsum, gypsum α and β, with different water content were prepared. Samples without polypropylene fibers, fiber lengths during preparation, produced factory located Debar region, North Macedonia, studied. Physical properties such as density, porosity, ab...

continuous exposure to high-energy ultrasonic waves depolymerises macromolecules in solutions and produces a permanent reduction in viscosity. different factors affect the efficiency of this ultrasonic depolymerisation. in this work ultrasonic degradation of one commercially important hydrogel based on acrylic acid and acrylamide was carried out in aqueous solution at room temperature (25oc). a...

Coherent ultrasonic Doppler velocimeters provide precise and accurate measurements of velocity profiles in many applications. However, these instruments suffer from the well known range-velocity ambiguity, making this kind of instruments not well suited for velocity measurements in channels of several meters depth and water velocities of some meters per second. On the other side, incoherent ult...

Pulse period of earthquake records has been known as a key parameter in seismology and earthquake engineering. This paper presents a detailed characterization of this parameter for a special class of earthquake records called pulse-like ground motions. This type of motions often resulting from directivity effects is characterized by a strong pulse in the velocity time history of motion, in norm...

The objective of this study was to examine the potential of ultrasonic velocity as a rapid and nondestructive method to predict the dimensional stability of oak (Quercus petraea (Mattuschka) Lieblein) and chestnut (Castanea sativa Mill.) that are commonly used in flooring industry. Ultrasonic velocity, specific gravity, and radial, tangential and volumetric shrinkages were measured on seventy-f...

The production of ordinary Portland cement (OPC) as the most expensive constituent of concrete is associated with destructive environmental effects and significant energy consumption. Thus, the use of supplementary cementitious materials such as Natural or synthetic pozzolans is a fundamental solution that affects the kinetics of hydration of cementitious materials. In this article, to evaluate...