Today, the road construction profession is more than ever facing limited and increasingly expensive resources for component materials of asphalt mixtures, which has also led to the need for continuous research on the use of waste materials. One such potentially usable waste material is ash obtained by the combustion of wood biomass that is used to produce heat and electricity. The goal of this paper is to ascertain the possibility of using wood ash (WA) as the filler in asphalt concrete mixtures for the base-wearing layers of a pavement. The properties of Marshall stability (MS), quotient (MQ) and deformations, and the indirect tensile strength of water-conditioned samples and dry samples were tested on asphalt samples of an AC16 surf mixture with different contents of wood ash as the filler. The obtained values of MS and MQ indicate that a 50% content of bio ash in the filler results in an increase in asphalt’s resistance to the appearance of plastic deformations and greater tensile strength and in good asphalt resistance to the action of water.

In this study, we evaluated the elastic and mechanical properties of a new type of cement-stabilised material made with steel slag, varying the content of cement and steel slag. To study the elastic properties of these mixes, we measured their density, compressive strength and ultrasound pulse velocity at curing ages of 7, 28 and 90 days. The aggregate type and curing age greatly affected the elastic properties and varied much depending on the cement content. The Poisson's ratio chosen in analyses had little influence on the dynamic modulus. Various expressions given by building codes were used to predict the elastic properties of the mixtures. These codes generated very different values of the static modulus of elasticity, making most of them unsuitable for predicting the elastic properties of cement-stabilised materials. Using our experimental data, we provide the best combination of existing equations to predict elastic properties, and we conclude that measuring the ultrasound pulse velocity is a suitable way to predict the mechanic and elastic properties of cement-stabilised materials.

Application of nondestructive methods in assessing the properties of materials and mixes is very popular because of their simplicity and noninvasive nature. The ultrasonic method is, as one of nondestructive methods, used for more than 60 years in determining the properties of concrete mixes. However, only recently it has been applied application in studies of the stabilization mixes intended for road construction. The ultrasonic method is based on measurement of the travel time of longitudinal ultrasonic waves through the sample. In this paper, the investigation of stabilized mixes containing sand from river Drava stabilized with cement and fly ash are presented. The aim of the research was to determine the impact of changes in the composition of mixes and in the regime of care on the density, compressive strength and ultrasonic velocity. An additional goal was to analyze the relationship between the investigated properties of mixes and the ultrasonic velocity. The compressive strength of the stabilized mixture is determined by the destructive method according to Croatian Standards HRN.U.B1.030 Unconfined Compressive Strength as the average stress in a sample during uniaxial compression testing at the ultimate force. Testing of density and compressive strength of mixes and determination of the ultrasonic speed has been performed after 7, 28 and 90 days of curing at four different temperatures: 5 ?C, 15 ?C, 25 ?C and 35 ?C. The obtained results indicated the direct influence of fly ash quantity on the observed properties. Increase in the amount of fly ash caused a decrease in the mixture compressive strength, its density and ultrasonic velocity. A significant influence of treatment temperature on the compressive strength, density and ultrasonic velocity was also observed. Finally, correlation between density and ultrasonic velocity, as well as compressive strength and ultrasonic velocity was established. Exponential relationship between the compressive strength of stabilized mixes and ultrasonic velocity proved to be very strong, and similar to those obtained in previous studies by other researchers. Test results showed that the ultrasonic method can be useful in assessing properties of stabilized mixes.

The influence of the calendaring process of nonwoven geotextiles on the water permeability normal to their planes, including influence of different loads, as well as pore characteristics investigated by two different methods has been studied. Methods of pore characteristics differ in obtaining different pore parameters. Two groups of samples were produced whereas first group is bonded by needle punching, while second group is needle punched samples taken from first group and additionally bonded by calendaring. Mass per unit area for both groups is in range of 150 to 500 g/m², with increasing by 50 g/m² for the next sample within groups. Calendaring process decrease water permeability of geotextile, but also decreases interval of geotextile water permeability change due to the applied pressure. Calendared geotextiles have controlled and predictable compressibility, respectively structure which will not significantly change in the practical application.