Albinas Gailius

Consistency of fly ash and Metakaolin concrete

Abstract As high‐performance Portland cement (PC), fly ash (FA) and metakaolin (MK) concrete have been developed in wide applications, it has growing interest in optimizing and predicting consistency of fresh PC‐FA‐MK concrete for efficient and practical design and construction. This paper presents statistical models for predicting the consistency of concrete incorporating PC, FA and MK from the experimental results of standard consistency tests. They reflect the effect of variations of pozzolanic replacement materials including FA and MK at graduated replacement levels of up to 40% and 15%, respectively. The predictions produced are compared with the experimental results of consistency of concrete blends. Models show that they can be used to predict the consistency parameters including slump, compacting factor and Vebe time with a good degree of accuracy in a wide range of FA‐MK blends. Design guidelines for evaluating consistency parameters are tentatively recommended along with their confidence interva...

Sustainable medium‐strength concrete (CS‐concrete) from colliery spoil in South Wales UK

Abstract This paper reviews one way in which colliery spoil can be utilized in low‐strength concrete. Colliery Spoil (CS) (minestone), a by‐product of coal mining, is abundant in most parts of the world. It has potential as a construction material but it has not been fully appreciated. This is partly because colliery spoil is not easy to utilize, due a number of drawbacks. The major problems identified in attempts to utilize CS in construction include excessive wear, expansive behaviour, leaching of heavy metals and even radioactivity. Thus, to date, the bulk of the CS utilization is limited to isolated cases of highway embankments, backfilling of mines, quarries and other surface tips, or in extreme cases subjected to marine and other disposal. This paper reports on the scope of technological benefits of utilizing colliery spoil (CS) in low to medium strength concrete. There has been intermittent pursuance of the benefits of utilizing colliery spoil in the United Kingdom. However, there is still no well‐...

The effect of vertical air gaps to thermal transmittance of horizontal thermal insulating layer

Abstract In order to reduce the amounts of work at the construction site, single‐ply dual density thermal insulating roofing boards are used with increasing frequency for thermal insulation of flat roofs. In this case, the joints between boards are not overlapped by the other ply over it; therefore gaps of varying width form between the sides of the boards through the entire thickness of the insulating layer, whose effect on the effective thermal conductivity of the thermal insulating layer must be evaluated. The aim of this project was to assess the reliability of standard method, used to determine the impact of such air gaps on the effective thermal conductivity of the thermal insulating layer by comparing the results of calculations and the results of measurements of thermal conductivity, also to determine the correction factors for thermal transmittance of horizontal thermal insulation layers due to the forming vertical air gaps between the single‐ply mineral wool boards. After measurements of thermal...

Influence of cement type and admixtures on rheological properties of cement paste

AbstractThe article aims to research the influence of the chemical admixtures on the rheological properties of Portland cement paste and determine their impact on the effectiveness of hydration induction period. Materials used in the study: Portland cement CEM I 42.5 (N and R early strength), limestone Portland cement CEM II/A-LL 42.5 N, plasticizer Centrament N3, the latest generation superplasticizer MC-PowerFlow 3140 and water. Investigations focused on effects of Plasticizer and superplasticizer on water and cement (W/C) ratio and Portland cement paste flow characteristics. Portland cement pastes with the same watercement ratio with and without chemical admixtures were tested. Investigations were carried out using a Suttard viscometer and rotation viscometer Rheotest NH 4.1 with coaxial cylinders. It was observed that viscosity of Portland cement paste can be controlled by chemical admixtures during the hydration induction period. Investigations of effectiveness of the chemical admixtures on the rheol...

Utilization of boon and chaff for manufacturing lightweight walling materials

Abstract Lightweight composites for walls and thermal insulation, containing anhydrite (An) or aluminate cement (Al), vinyl acetate (VA) or cellulose (Cl) polymeric binders and cellulose fiber fillers (boon, chaff) were produced. The best results were obtained for transportation and construction of items containing: An ≥ 30–45 %, Al ≥ 30–50 %, VA ≥ 1–5 %, Cl ≥ 0,5–5,0 %, boon or chaff ≥ 40–47 %. Polymeric binder VA for both kinds of cement is better than Cl. An is better for boon than for chaff. Aluminate cement is a good binder for both types of fiber fillers. Density r of a composite containing cements 50–60 % is less than 400 kg/m3. According to density such composite materials are light‐weight heat‐insulating materials. Density (p ≤ kg/m3) depends on the amount of cement content. Bending strength for samples with p ≤ 400 kg/m3, containing CMC is 0,6–1,3 MPa. Coefficient of thermal conductivity for samples, density with 400 kg/m3 is 0,06 W/m‐K.

WASTE PAPER SLUDGE ASH AND GROUND GRANULATED BLAST FURNACE SLAG AS BINDER IN CONCRETE

The aim of the research was to develop an economic binder from waste products that could have applications in the production of concrete. Portland cement (PC) production is a very high-energy inten...

Šiaudų naudojimo galimybių termoizoliacinių medžiagų gamybai tyrimai@@@Analysis of Thermal Insulation from Renewable Resources

Santrauka Vienas esminių statinio reikalavimų – energijos taupymas ir silumos issaugojimas. Apytiksliai 40 % visos Europos Sąjungoje suvartojamos energijos tenka sildomų pastatų eksploatacijai. Didžiąją sių sąnaudų dalį sudaro energija, suvartojama pastatams sildyti saltuoju metų laikotarpiu ir jiems vėsinti siltuoju metų laikotarpiu. Kelis kartus mažiau energijos galima suvartoti gaminant termoizoliacines medžiagas is atsinaujinanciųjų isteklių ir jomis siltinant pastatus. Tokių medžiagų silumos laidumo koeficientas yra apytiksliai 0,040 W/(mK). Darbe nagrinėjamos siaudų naudojimo galimybės termoizoliacinių medžiagų gamybai. Pateikti atliktų įvairaus tankio siaudų silumos laidumo tyrimų laboratorinėmis sąlygomis ir vakuumuotoje aplinkoje rezultatai.

DETERMINATION OF THERMAL-MECHANICAL PROPERTIES OF CONCRETE

Abstract The aim of this investigation was to find the relationship between different percentage of damage and thermal conductivity of concrete. The influence of different damage on thermal conductivity of concrete was determined. The method with insulation (ordinary method) based on the temperature difference measurement between two surfaces of specimen, when one of the surfaces is heated, was used for thermal conductivity measurement. Three specimens for every percentage of damage were used for each measurement of thermal conductivity. After this research one conclusion can be made definitely: influence of different percentage of damage on thermal conductivity of concrete.