MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

The hydraulic properties of ash from incinerated wastepaper sludge were investigated. It is shown that the phase composition of wastepaper sludge after heat treatment is similar to the classical fired carbonate-clay mixes. The necessity of using the combination of retarding admixtures with different action mechanism is shown. The strength in the initial hardening period is ensured by the formation of AFm-phases and ettringite, and subsequently by increasing the role of CSH.

Concrete block pavements have become an attractive engineering and economical alternative to both flexible and rigid pavements because of it’s high strength and durability. The influence of pozzolanic mineral additions – natural zeolite and expanded perlite powder on the properties of concrete interlocking blocks in different curing conditions has been studied. The use of zeolite as a substitute for cement in the production of concrete blocks increased the water demand but decreased the water absorption of the blocks. Obtained results show, that concrete blocks with 10% substitution of cement with zeolitic tuff is characterized by higher strength, lower mass loss and absence of efflorescence.

In this article the potentiality is proven for application of wastepaper sludge ash (WSA) as mineral powder for traditional hot asphalt concrete mix. For the comparative testing in this article the traditional limestone mineral powder is used. The chemical (oxide) composition of the aggregates was studied, while that was determined by means of DRON - 3.0 diffractometer. It was ascertained that CaO is present in wastepaper sludge ash in sufficient quantity, while it provides for utilization of this waste material as an aggregate for asphalt concrete. The limestone mineral powder granulometric composition was determined and the wastepaper sludge ash was grinded by ball grinder till the appropriate granulometric composition was reached. There were studied the main physical and mechanical parameters of bitumen 70/100 to be used for formation of asphalt binder in combination with the studied mineral aggregate. There were formed the following series of traditional hot asphalt concrete mix: on limestone mineral powder, on wastepaper sludge ash, on both limestone mineral powder and wastepaper sludge ash in ratio 50/50, 30/70, 20/80 (% w/w). By means of grading curves of dense-graded continuous mixes there was designed the chip-grain carcass of asphalt concrete mix. The asphalt concrete mix was designed based on the following characteristics: hot fine-grained densegraded asphalt concrete with residual porosity from 2 % to 5 %, with quantity of chip-grains sized more than 5 mm – 35-45 % and the maximum grain-size up to 15 mm. There was determined that WSA can perform as material to be used as mineral powder for asphalt concrete mixes. According to the requirements of Ukrainian standard (DSTU B V.2.7-119:2011), the asphalt concrete with WSA is of standard condition, but the water-saturation index approaches the acceptably allowed value, while in comparison with asphalt concrete with LMP – it is higher by 55%. Such result is due to the difference in oxide composition of the aggregates, namely lower content of products of calcareous rock in WSA. With combined application of limestone mineral powder and WSA in ratio 50/50, 30/70, 20/80 (% w/w) the water-saturation index decreases. As to the compression tensile strength and compression tensile strength after water-saturation, these indices on WSA are lower than on LMP just by 10%. The most efficient usage of WSA, considering the studies done, can be achieved when coupled with LMP in ratio 50/50.

This study aimed to evaluate the influence of zeolitic tuff, an air-entraining agent, and different types of fibers on the compressive strength and fracture parameters of concrete with increased strength. Notched beams were tested in three-point bending to determine the fracture parameters of concrete. It was established that the partial replacement of Portland cement (10% by mass) with zeolitic tuff, the addition of an air-entraining agent and different types of fibers resulted in the improvement both of the compressive strength (by 3.7% after 28 days of hardening) and fracture properties of concrete (namely, the fracture energy by 35.1% and characteristic length by 61.5%) compared to the reference concrete. The beneficial effects of the air-entraining agent and the mechanisms through which it enhances the properties of concrete by incorporating zeolitic tuff and various types of fibers were explained. It has been demonstrated that the appropriate selection and optimization of various technological factors enable the production of economically effective, high-quality concrete with a 10% lower cement content. As a result, this leads to reduced CO₂ emissions, aligning with a sustainable development strategy.