Fabrication of porous ceramics as clay/glass composite

Nowadays porous ceramics are widely researched, becoming an increasingly marketable material in the world, mainly due to the wide possibilities of usage in different technical and technology industries. Porous ceramics are successfully used in the filtration and has a high potential of usage also in the production of heat insulation materials thus obtaining the material which combine high resistance that can compete with other heat insulation and constructive materials.Article reports a study of porous ceramics, which are produced using foamglass pellets as melting fillers, despite the fact that these additives are not frequently used as filler in traditional ceramic materials. The basis of this method is mixing fire resistant material with hard and melting substance.For the production of porous ceramics clay, hard filler, water and various sized foamglass pellets were used, thus allowing to determine optimal size of melting filler and thereby ensuring the necessary physical and mechanical properties of the obtained porous ceramic samples and required amount, size and division of pores.  Compressive strength tests were performed, as well as density and water absorption of the samples was determined.Obtained results of the study shows that ceramic materials, obtained within the research, have great potential of application for load-bearing constructions as constructive building materials, as well as insulation materials. Production of porous ceramics materials, where foamglass pellets are used as melting filler, allows to produce more effective ceramics, creating high added value for the final product.

Sand Partial and Full Replacement in Concrete Composite with Rubber Crumbs

The objective of the research on rubberized concrete that substitutes sand fillers with rubber crumbs by volume or weight is to identify ways to utilize discarded rubber tires and improve the building industry’s sustainability. The research indicates that substituting sand fillers with rubber crumbs can have a substantial effect on the concrete’s physical and mechanical qualities. Significant decreases in flexural strength and compressive strength are observed when 100 % of the sand is replaced with rubber crumbs, showing that the attributes of rubber concrete are weaker than those of conventional concrete. Note that the precise mix design and proportion of rubber crumb replacement will alter the qualities of rubber concrete. Therefore, it is essential to conduct proper laboratory testing and trial mixing in order to optimize the mix design and determine the replacement % that would deliver the needed qualities and match the standards. The flexural strength of the reference sample was 2.7 MPa and its compressive strength was 57.7 MPa, compared to the compressive strength of the sample in which 100 % of the sand was replaced with rubber crumbs. The flexural strength of sr100 was 0.39 MPa and its compressive strength was 4.4 MPa. It is also important to note that rubberized concrete may still have some advantages over ordinary concrete, such as enhanced sound insulation, thermal insulation, and chloride ion penetration resistance. These characteristics may make it useful for applications including sound barriers, underground constructions, and marine structures

Alkali Activated Binders Based on Metakaolin

According to research conducted in last 25 years, alkali activated binders have been considered as one of the most progressive alternative binders, which can effectively replace Portland cement. Production of alkali activated binders differs from the Portland cement production and is associated with lower CO2 emissions. The use of recycled industrial by-products and wastes is also possible, what corresponds to the future guidelines and principles of sustainable binder production in the world.The aim of this study was to create innovative alkali activated binders by using secondary raw materials, which will be different from the ones described in the scientific literature – alkali activated binders with porous structure. Raw materials used for the binders were metakaolin containing waste, waste from aluminium scrap recycling factory and recycled lead-silicate glass; solid contents were activated with modified sodium silicate solution with an addition of sodium hydroxide.The physical properties of alkali activated binders, such as density, water absorption, open and total porosity, were determined and flexural and compressive strength of hardened alkali-activated binders were tested at the age of 28 days. Durability was examined by sulphate resistance test, which was performed according to SIA 262/1, appendix D: applicability and relevance for use in practice. 40x40x160 mm prismatic specimens were used for expansion measurement and determination of compressive strength. The open porosity of obtained materials was up to 45%, density from 380 to 1720 kg/m3, compressive strength up to 29,8 MPa, water absorption 6 – 114 wt.%. After analysing the results from the sulphate test it was concluded that glass additive reduced the alkali activated binder resistance to sulphate attack

Comparison of Pozzolanic Additives for Normal and High Strength Concrete

Microsilica is widely recognized as a “benchmark” for pozzolanic products. Although microsilica is an industrial byproduct, it has recently become very expensive. Four different pozzolanic additives were compared by the authors of this study. Two of the additives were commercially available products – microsilica by Elkem and Centrilit NC by MC Bauchemie. The other two additives were produced under laboratory conditions. Both of them were clay-based materials. Compressive strength was determined after 7, 28 and 155 days. The objective of this research was to determine alternatives to microsilica and evaluate pozzolanic additives performance in normal and high-strength concrete

The Effect of Heat Treatment on the Properties of Ultra High Strength Concrete

The influence of heat treatment during curing process of ultra high strength concrete (UHSC) was researched. Four different heat treatment temperatures ranging from 50 to 200 °C were studied and compared to the reference temperature regime (20 °C).  Two series of heat treatment were applied: (a) at the early age of UHSC (3 days) and (b) after 27 days of standard curing regime in water at 20 °C. Concrete compressive strength was tested at the early age (4 days) and at the age of 28 days. The water absorption and water penetration under pressure were tested for heat treated and untreated UHSC specimens. SEM and XRD investigations of the studied samples were performed. UHSC with the strength of 123 MPa at the age of 28 days was tested at the standard curing conditions. Results indicate that early age curing at elevated temperature increases early compressive strength from 123 to 189% while at the age of 28 days the compressive strength was only 95 to 117% from reference and depends on the heat treatment regime. The heat treatment of UHSC at the age of 27 days was beneficial with regard to the strength development. Heat-treated UHSC provided compressive strength gain from 112 to 124% from reference. The water absorption for all UHSC specimens was from 2.6 to 3.2 wt.% and it was not affected by the heat treatment. The calcite was detected with XRD in heat treated UHSC samples which indicates the carbonization of Portlandite. This could explain the strength gain of heat-treated samples and the reason for slow compressive strength increase in the case of early heat treatment application. SEM images reveal dense structure and unreacted silica fume particles. The early heat treatment initiated high early strength but the strength of concrete reduced at the age of 28 days comparing to the early strength; therefore late heat application was beneficial for strength gain of the UHSC

Utilizing Manufacturing Waste by Developing New Bio-Based Building Materials

In the last decade, more research has been concentrated on reducing the usage of natural resources and waste management in construction building materials. There are many possibilities for reducing the waste from this sector, ranging from waste being used as filler materials to developing new binders and building materials. This research concentrates on bio-based building material development from wood-wool cement board manufacturing waste. The authors have found that a new bio-based building material can be produced using manufacturing waste. Two fractions of waste were used in this study. One fraction was the wood wool fibers mixed with cement that have fallen off the manufacturing chain and thus cannot be used to make wood-wool cement boards. This fraction was used as the filler material. The second fraction was the dust fraction in the quality assessment phase, where the wood-wool cement boards are sanded for better surface quality. This fraction is then vacuumed out of the manufacturing plant to avoid air pollution from the dust particles. The dust fraction contains wood wool fibers and hydrated and unhydrated cement particles. The cement particles are conglomerated when the mixing process of water, cement and wood fibers occurs. The hydrated cement particles stick around the unhydrated cement particles, encapsulating them. This results in not all the cement used to manufacture wood-wool cement boards. These conglomerates, however, can be broken down with a milling process and can hydrate once the water has been added. The binder with the filler material was used to develop bio-based building materials. The developed materials were tested for their apparent density, compressive strength, and thermal conductivity coefficient. The obtained results showed promising data for self-bearing bio-based building materials to be similar to other bio-based materials for their thermal properties and use as thermal insulation materials. The apparent density of the developed bio-based composites was 384–555 kg/ m3. The conclusion was made that by using waste materials for the production of bio-based building materials, it is possible to reduce the overall waste of the manufacturing plant and increase the sustainability aspect of wood-cement board manufacturers

Influence of the carbonate-free clay calcination temperature and curing conditions on the properties of alkali-activated mortar

Alkali-activated materials (AAMs) are one of the most perspective alternatives to the traditional Portland cement based materials. AAMs could reduce the environmental pollution and greenhouse gas emission due to the lower heat consumption in production (up to 80% compared to the ordinary Portland cement). In the current research alkali-activated mortar was developed from the locally available low-carbonate Illite clay. Experimental work consisted of Illite clay calcination at different temperatures and regimes (from 500-800°C) and incorporation of the obtained material into the mixture of alkali-activated mortar. Four curing regimes were applied to alkali-activated mortar. The results indicate that hardened mortar properties are mainly affected by curing temperature and regime and the compressive strength up to 28.8MPa could be achieved for the mortar samples aged 2 months

Effect of Pozzolanic Additives on the Strength Development of High Performance Concrete

The aim of this research is to estimate the effect of pozzolanic substitutes on the temperature generated by the hydration and on the final strength of concrete. Differential thermal analyses (DTA) were conducted. Ternary cementitious systems with different ratios of Portland cement, silica fume and calcined illite clay were investigated. The results showed that the rates of pozzolanic reaction and portlandite consumption in the silica fume-blended cement pastes are higher than in the illite clay-blended cement pastes.12th international conference “Modern Building Materials, Structures and Techniques” (MBMST 2016)The research leading to these results has received the funding from Latvia state research program under grant agreement "Innovative materials and smart technologies for environmental safety, IMATEH”