Maria Ratajczak

Effect of Modern Air Entraining Admixtures on Physical Properties of Construction Mortars

The basic feature characterising the concrete’s quality and its usefulness for a structure is compressive strength. However, other features, such as frost resistance, absorbability, tightness, abrasiveness, decide on the durability of concrete in the structure as well. The paper presents the results of tests conducted on an ecological air entraining agent applied as a concrete mix admixture. The air entrainment of a concrete mix is aimed at entraining additional air pores with appropriate shape, size, and distribution into the concrete structure. The air entrainment is one of the main technological processes aimed at improving the concrete’s resistance to destructive effect of frost [1,2,3,4].

Ecological hydrophobizing admixture in special purpose concretes

Nowadays, on the construction market, there are offered agents for concrete hydrophobization. In most cases, these are preparations that are applied on surfaces of already existing elements. The main disadvantage of such agents are strictly specified conditions, under which they can be applied. It is not recommended to apply the preparations for the elements under water level, exposed to contact with water under pressure, and with visible cracks and scratches [1, 2]. The article presents the results of tests of an innovative agent for concrete hydrophobization that has not disadvantages of the currently applied materials – application of the developed solution takes place at the stage of creating concrete mix. The preparation may be classified as an admixture for concretes.

Analysis of Selected Rheological Properties and Ageing Processes of Bitumens Used in Waterproofing Products

Commonly used waterproofing membranes consist, in over 80%, of bituminous blend. That is why thorough knowledge of factors having impact on the destruction of waterproofing products is of utmost importance. In many cases it is caused by rheological changes, especially ageing processes occurring in bitumen. The purpose of the research is to develop modern solutions that will slow down the processes which occur and thus will extend the life of waterproofing materials. The paper discusses factors affecting the intensity of bitumen ageing and describes physicochemical changes caused by ageing. It also presents test results of bitumen modified with imidazoline which can be used as inhibitors of ageing processes.

Assessment of resistance to fragmentation of crushed-stone aggregate for the application in road engineering

A lot of research centres in the world deal with developing the reuse of waste technology. The processed waste is applied in many industries, especially in the infrastructure construction. The European standards allow to apply recycled materials in implementation of buildings and the road engineering. In most cases, the detailed classifications for recycled aggregates are the subject of domestic standards, in which this topic is studied and developed deeply (Germany, Austria). In Poland, at the stage of applying the recycled aggregate, contractors are forced to rely on German or Austrian guidelines. In many cases, the application of the recycled materials is based on the contractors’ experience or intuition. That is why each additional development expansion of the knowledge on the recycled aggregates is added value and is very helpful for designers and contractors. The paper presents the comparison of mechanical resistance to fragmentation in a Los Angeles abrasion machine of selected crushed-stone and recycled aggregates (crushed concrete rubble) from demolished road structures.

Innovative Additive for Bitumen Based on Processed Fats

Various additives, admixtures and modifiers are used to improve technical properties and strength characteristics of building materials. Manufacturers of waterproofing materials, concrete, ceramics and bitumen have to use innovative, increasingly complex and costly additives, admixtures or modifiers. As a result, simple and inexpensive substances have been replaced by complex, long chain polymers, multi component resins or plastics. For economic and ecological reasons waste materials are more frequently used as additives, admixtures and modifiers. Nowadays the most commonly used physical modifiers of bitumen belong to the group of polymers - large molecular organic compounds of natural origin or being the result of planned chemical synthesis. Polymers are substances that do not chemically react with bitumen, they act as fillers or create a spatial network within bitumen (the so called physical cross-linking). The development of organic chemistry has allowed the synthesis of a number of substances chemically modifying bitumen. The most promising are heterocyclic organic compounds belonging to the group of imidazolines. The aim of the study presented in this paper was to demonstrate the suitability of processed natural and post-refining fat waste (diamidoamine dehydrate) as bitumen modifier. This paper discusses the impact of adding technical imidazoline on selected bitumen characteristics. Samples of bitumen 160/220, which is most commonly used for the production of waterproofing products, were analysed. For base bitumen and bitumen modified with technical imidazoline the following measurements were taken: measurement of the softening point by Ball and Ring method, determination of the breaking point by Fraass method and needle penetration measurement at 25°C. Later the samples were aged using TFOT laboratory method and the basic characteristics were determined again. The results showed that a small amount of imidazoline improved bitumen thermoplastic parameters at low temperatures and had a significant impact on weakening bitumen oxidation and ageing. The addition of technical imidazoline prevents bitumen from hardening, thus increasing its flexibility and its resistance to mechanical damage. Due to many difficulties in the production of polymer bitumens and in order to find cheaper, more environment friendly solutions, the authors proposed an ecological bituminous modifier which, due to chemical reaction with binders, creates a stable and firm in time product. Imidazolines have a negative impact on bitumen softening point, which makes them impossible to use as an independent modifier. Therefore, at a later stage of the research, the authors will attempt to create a hybrid bitumen modifier which will combine the beneficial effect of polymers and imidazoline on the characteristics of bituminous binders.