Thermal Insulation Blocks Made of Sunflower Pith Particles and Polysaccharide-Based Binders: Influence of Binder Type and Content on Their Characteristics

Co-product of sunflower cultivation, pith of stem has a little exploited insulating potential. Blocks in which pith particles are glued together using a starch-based binder have already been obtained. However, they are highly water-sensitive. Replacing this binder with others has been considered here. Polysaccharide-based binders were tested, chosen for their more hydrophobic character: sodium alginate, chitosan, Citrus pectin, and a modified starch. Like starch, these binders are physically binding. They are first solubilised in water (except chitosan, dissolved in 2% acetic acid). The solution is then mixed with pith particles before cold compression molding for 90 s. A 10% binder content was initially considered. The blocks were all cohesive with a dry density from 36 to 42 kg/m3). Their performances were assessed through water absorption capacity and resistance via capillary absorption tests on wet sponges, mechanical test and thermal conductivity. Chitosan and pectin-based blocks show the best properties, particularly concerning water resistance and mechanical properties. The pectin-based block has improved its elastic modulus by 40% compared to a starch-based block. The pectin-based block in its case absorbs 2.7 times less water than starch. Finally, thermal conductivities of pectin and chitosan-based pith blocks are in the same order of magnitude as for starch (39.8-40.1 mW/m.K), and close to values from commercial materials (e.g., polystyrene). Pectin and chitosan were also tested at three rates (5%, 10% and 15%). A significant improvement in the blocks' compressive strength was observed with the increase in binder rate, while thermal conductivities varied little.

Integrated approach to the man-made waste use in the building materials production

The article deals with the issues of the man-made waste use effectively in the building materials production, particular in non-autoclaved aerated concrete and granular aggregate. The basic properties of organic waste of flax bonfires and inorganic waste - ash from incineration of sewage sludge are determined. The optimal ratio selection of aggregates in non-autoclave aerated concrete is made. It is established that the use of flax bonfires makes it possible to partially or completely replace quartz sand in raw mixtures composition for producing aerated concrete. The dependence of the porous structure process on the temperature of aerated concrete mixture during the swelling period is investigated. Depending on a binder type and a technology, two methods of granulating materials, based on crushed flax and ash from wastewater sludge incineration are proposed.

Multi-Level Laboratory Performance Evaluation of Conventional and High Polymer-Modified Asphalt Mixtures

Asphalt concrete (AC) overlays have been one of the most common treatments used by the Virginia Department of Transportation (VDOT) for maintaining/rehabilitating pavements. However, when the overlay is placed on existing composite pavements or cracked AC pavements, differential movements across any cracks or joints can result in physical tearing of the AC overlay. Thus, the long-term performance of many AC overlays will highly depend on their ability to resist cracking. The purpose of this study was to assess the viability of using high polymer-modified (HP) AC mixtures in Virginia as a crack mitigation technique or when deemed appropriate as a tool for increased resistance to rutting and cracking on higher volume facilities. Another objective was to assess the ability of various testing protocols to discern the performance of pavements through a comprehensive evaluation of three conventional polymer-modified (PMA) and five HP field-produced mixtures placed in Virginia. This included laboratory testing at multiple levels of complexity (basic, intermediate, and advanced) on collected asphalt binders, plant-produced asphalt mixtures, and field cores. The performance characteristics of PMA and HP mixes were evaluated in the laboratory in relation to durability and resistance to rutting and cracking. Based on the mixes tested, stone matrix asphalt (SMA) mixes showed better performance than dense-graded surface mixes (SM) regardless of the asphalt binder type. Moreover, HP mixes showed better performance than PMA mixes regardless of the mixture type. Overall, SMA-HP mixes showed the most promising performance among all evaluated mixes.

Effect of Aggregate and Binder Type on the Functional and Durability Parameters of Lightweight Repair Mortars

The subject matter of the work presented here is the development and evaluation of novel lightweight mortars that meet the functional and technical criteria imposed on repair mortars. In a broad experimental campaign, lime, natural hydraulic lime, and lime–cement mortars were designed and tested. Lightweight aggregate, expanded perlite, granules from expanded glass and zeolite were used as full replacements for quartz sand. The hardened mortars were tested at the ages of 28 days and 90 days. The conducted tests and analyses were focused on the assessment of structural, mechanical, hygric and thermal parameters. The salt crystallization resistance and effect of salt presence on the hygroscopicity of the investigated mortars were also investigated. The use of lightweight aggregates in the composition of mortars resulted in their high porosity, low density, satisfactory mechanical parameters, improved water vapor transmission capability and water absorption. The mortars with expanded perlite and glass granulate were ranked among thermal insulation mortars of classes T1 and T2, respectively. The use of lightweight aggregates enabled the development of mortars with great durability in terms of salt action, which was almost independent of binder type. The ability to accommodate water vapor was increased by the effect, i.e., the use of lightweight aggregates and the presence of salt in mortars increased porous space. Taking into account the compatibility, functional, and technical criteria, lime- and natural hydraulic lime-based lightweight mortarswere classified as repair mortars, providing improved thermal performance. The lime–cement lightweight plasters can be recommended only for repair of building structures where cement and lime–cement materials were original applied.

Structured asphalt binder is a new binder type in asphalt concrete mixtures

The data presented in the article are part of disserta-tion research on the formula development and pro-duction principle of composite material for road con-struction with phosphogypsum and secondary poly-ethyleneterephthalate use. The article provides an assessment of the existing most successful and effec-tive technologies for creating asphalt concrete pave-ments with high technical performance characteris-tics, and the key role in formula is an asphalt binder on the binary system mineral powder/oil road bitu-men basement, their main advantages and disad-vantages are described. A new technological method for the asphalt concrete mixtures production is de-scribed - pelletization by rolling, which was proposed by the authors. The paper presents the study's results to determine the structured asphalt binder technical and operational properties obtained by the method of pelletization by rolling. A brief theoretical substantia-tion of the physicochemical nature of improving a number of developed composition technical and op-erational characteristics of a structured asphalt binder is presented. The dynamics of over time changes in the main structured asphalt binder indicators, from 2005 to 2019, are given. It has been theoretically proven that in a structured asphalt binder obtained by the method of pelletization by rolling, bitumen is in a film state, and the bitumen interlayers thickness be-tween the mineral powder particles is of the order of 100 nm, which makes it possible to classify the prod-uct as a nanomaterial and determines its special properties set. The data of independent and our own experimental studies are also presented, indicating the previously obtained theoretical justification correct-ness for increasing the strength indicators, improving the water saturation indicators, and the water re-sistance coefficient. The absence of negative changes in the main technical and operational properties dy-namics for 14 years confirms the possibility of storing the mixture in a cold form outside a sealed package in an unheated room, which makes it possible to assert the possibility of preparing material for future use and transporting it over unlimited distances.

Structured asphalt binder is a new binder type in asphalt concrete mixtures

The data presented in the article are part of disserta-tion research on the formula development and pro-duction principle of composite material for road con-struction with phosphogypsum and secondary poly-ethyleneterephthalate use. The article provides an assessment of the existing most successful and effec-tive technologies for creating asphalt concrete pave-ments with high technical performance characteris-tics, and the key role in formula is an asphalt binder on the binary system mineral powder/oil road bitu-men basement, their main advantages and disad-vantages are described. A new technological method for the asphalt concrete mixtures production is de-scribed - pelletization by rolling, which was proposed by the authors. The paper presents the study's results to determine the structured asphalt binder technical and operational properties obtained by the method of pelletization by rolling. A brief theoretical substantia-tion of the physicochemical nature of improving a number of developed composition technical and op-erational characteristics of a structured asphalt binder is presented. The dynamics of over time changes in the main structured asphalt binder indicators, from 2005 to 2019, are given. It has been theoretically proven that in a structured asphalt binder obtained by the method of pelletization by rolling, bitumen is in a film state, and the bitumen interlayers thickness be-tween the mineral powder particles is of the order of 100 nm, which makes it possible to classify the prod-uct as a nanomaterial and determines its special properties set. The data of independent and our own experimental studies are also presented, indicating the previously obtained theoretical justification correct-ness for increasing the strength indicators, improving the water saturation indicators, and the water re-sistance coefficient. The absence of negative changes in the main technical and operational properties dy-namics for 14 years confirms the possibility of storing the mixture in a cold form outside a sealed package in an unheated room, which makes it possible to assert the possibility of preparing material for future use and transporting it over unlimited distances

Development of a Sulfate Resistance Performance Test for Concrete by Tensile Strength Measurements: Determination of Test Conditions

Assessing the sulfate resistance of concrete is essential for the use of concrete in sulfate rich environments. A multitude of test methods exists worldwide, showing the relevance of the problem and the difficulty to find a suitable test setup. Testing the relative tensile strength of ASTM C307 concrete briquette specimens after exposure to a sulfate solution is a new direct method to assess the degree of deterioration. The aim of this study is to develop a new performance test, which considers both the chemical and physical resistance of a specific concrete mix against sulfate attack. In the experimental investigations, the binder type, storage temperature, type and concentration of sulfate solution, and concrete composition were varied, and the remaining tensile strength evaluated to define the test parameters. To gain significantly distinguishable data within nine months of storage, the use of sodium sulfate solution with 6000 mg SO42−/l at 5 °C is proposed.