showing 14 related works from this author
Locally Produced UHPC: The Influence of Type and Content of Steel Fibres
2021
Abstract Ultra-high performance concrete might be a competitive alternative to normal concrete for some purposes. But despite research efforts during decades, utilisation is still not widespread. Reasons include limited competence and material availability. This paper presents one step of a research initiative aimed at facilitating the use of UHPC in Norway. The step presented here comprises the accumulated results from investigations on the influence steel fibres (content, type, and hybrid combination) have on material strength and deformation behaviour of locally produced UHPC, made with constituents found in southern Norway. 231 specimens were tested, spanning nine UHPC mixes. Digital Im…
Inconsistencies in the pozzolanic strength activity index (SAI) for silica fume according to EN and ASTM
2014
Published version of an article in the journal: Materials and Structures. Also available from the publisher at: http://dx.doi.org/10.1617/s11527-014-0457-6 Open Access New supplementary cementitious materials claimed to possess pozzolan properties emerge frequently. This development is driven both by economic and environmental pressures. Properties of new materials are compared with those of materials already well known, such as silica fume. Several test methods are standardized for making such comparisons, regulated by both European (EN) and American (ASTM) standards. Standardization indicates that procedures are secured to make comparisons valid and informative. In this article the sensit…
From Waste to Resource – Utilising Residue from Ready-Made Concrete as New Aggregate
2021
Abstract A new admixture is available, to reduce the sludge produced from the cleansing of production and transportation equipment in the fresh concrete industry. The result is agglomerations of hardening concrete, that might be utilised for aggregate. Utilisation depends on adequate properties. This paper reports from investigations on the physical and mechanical properties of the aggregate and discussions on the performance relative to natural and recycled aggregates and towards requirements for utilisation. The findings indicate substantial potential for utilisation, supporting the reduction of waste for deposit and development of the concrete industry towards a circular economy.
Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests
2021
Rock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-De…
Quantitative Determination of Calcium Hydroxide by using Near Infrared Spectroscopy
2018
Calcium hydroxide (CH) is a by-product from hydration reaction of cement along with calcium silicate hydrate (C-S-H) gel. It helps to protect the steel reinforcements in concrete structures from corrosion process due to carbonation. The presence of calcium hydroxide provides a basic environment (pH˃10) that induces the formation of passive oxide film and keeps steel structures from corrosion. The detection and quantification of calcium hydroxide in concrete structures are important to understand the nature and state of the steel structures in concretes. In this research work, the variation of calcium hydroxide to calcium silicate ratios in cement were measured by using near-infrared spectro…
The influence of steel fibres on compressive and tensile strength of ultra high performance concrete : A review
2020
Abstract This review paper presents the effects of steel fibre reinforcement regarding the compressive and tensile strength of UHPC. The intention is to give an overview of the research field and supply guidance for future research. Relevant papers were identified through a systematic literature search. An accumulation of the results shows that fibres have potential for improving the tensile strength of UHPC. The effect depends on fibre content, type and hybrid combinations. The effect of fibres on compressive strength seems to be questionable. Variations in test specimen geometry and other factors might also influence the results.
Repeated Load Triaxial Testing of Recycled Excavation Materials Blended with Recycled Phyllite Materials
2022
Recycled Excavation Materials (REM) are becoming viable alternative construction resources due to their economic benefits. However, REM may be composed of weak rocks, e.g., phyllites, limiting the use in a base layer. The present paper attempts to further the knowledge of the mechanical performance of REM by performing Repeated Load Triaxial Tests (RLTT). REM are mixed with Recycled Phyllite Materials (RPM) in systematic blends of 0%, 25%, 50%, and 100%. The batches’ resilient modulus (MR) and permanent deformation (PD) characteristics were assessed to establish the maximum RPM allowed into REM while maintaining the required performance. Hicks and Monismith’s and Uzan’s mo…
Hydration Chemistry of Cement Studied by Near Infrared Spectroscopy
2018
Cement is a complex mixture of inorganic compounds which mainly composed of calcium silicates and calcium aluminates. Cement is mixed with water to form concrete. During the mixing calcium silicate hydrate (CSH) and calcium hydroxide are formed. The ratio of water/cement (w/c ratio) is important to obtain a mixture that gives optimum strength to the concrete. In this work, three different cement samples were mixed with water in four different ratios, including 0.35, 0.40, 0.45 and 0.55, respectively. The hydration process of cement was investigated by using near infrared (NIR) spectroscopy over a period of 28 days. The combination frequency of OH stretching and bending of water molecules gi…
Recycled aggregates derived from excavation materials — mechanical performance and identification of weak minerals
2022
AbstractThe present study investigates the mechanical performance of recycled aggregates derived from excavation materials (REM). REM is blended with different quantities of recycled phyllite materials (RPM) and is investigated by Los Angeles (LA) and micro-Deval (MD) tests. X-ray diffraction (XRD) and acid solubility test are performed on the pulverized fractions < 1.6 mm obtained from the LA and MD tests to assess the respective degree of fragmentation and wear of mineral components. The results of the materials in unblended conditions showed considerable difference between MD performance while similar performance was found for LA. Furthermore, about 40% of RPM was sufficient to blend …
Use of Concrete for Road Infrastructure: A SWOT Analysis Related to the three Catchwords Sustainability, Industrialisation and Digitalisation
2019
This paper aims at identifying the direction for more sustainable development of the use of concrete in road infrastructure in an industrialised context. The increase in the global mean temperature is one of the most severe challenges today. The concrete industry is responsible for significant emissions of greenhouse gases, most attributable to cement production. However, concrete is one of the most important building materials in the world and indispensable for the societal development in countries at all development stages. Thus, the concrete industry needs to take measures for reducing emissions. This paper investigates possible directions for the development of the concrete industry, to…
Determining the Environmental Benefits of Ultra High Performance Concrete as a Bridge Construction Material
2017
Ultra High Performance Concrete (UHPC) is a material that is attracting attention in the construction industry due to the high mechanical strength and durability, leading to structures having low maintenance requirements. The production of UHPC, however, has generally higher environmental impact than normal strength concrete due to the increased demand of cement required in the concrete mix. What is still not sufficiently investigated, is if the longer lifetime, slimmer construction and lower maintenance requirements lead to a net environmental benefit compared to standard concrete bridge design. This study utilizes life cycle assessment (LCA) to determine the lifetime impacts of two compar…
Preventing early age chloride migration into low-carbon concrete
2019
The use of substituting cementitious materials (SCMs) to produce low-carbon concrete is escalating. This contributes to reducing the anthropogenic emission of CO2, and to reduce harmful temperature gradients during cement hydration in massive structures. Mature low-carbon concretes are known to perform well on both strength and durability. However, the maturity process is slow compared to that of standard concrete. Structures made from low-carbon concrete are subject to penetration of agents like chloride at early age, accelerating degrading processes. Chloride penetration is a major problem especially to infrastructure, due to seawater proximity and the use of de-icing agents. Solutions fo…
Towards Efficient Use of Cement in Ultra High Performance Concrete
2021
Abstract This paper presents an investigation on substituting the cement content with an inert material, in a typical locally produced UHPC mix. A structured literature review was performed to enrichen the discussion and to benchmark the results towards already reported investigations in the research society. Investigations on cement substitution in UHPC are frequently reported. However, usually the cement is substituted with other binding materials – often pozzolanic by-products from other industries. Reports from investigations on the use of inert materials for cement substitution in UHPC seem scarce. An experimental program that included a total of 210 test specimens was executed. This p…
Lowering environmental impact from UHPC, utilizing industrial by-products
2018
Ultra High Performance Concrete (UHPC) is a material having some properties superior to ordinary concrete, such as strength and durability. Production ofUHPC often includes large amount of cement, leading to high cost and environmental footprint. This study aimed at demonstrating the potential of reducing both cost and environmental impact from production of UHPC, by reducing cement content through substitution with inert materials. Locally available industrial by-products were utilized as ag-gregates, as another mean to reduce cost and environmental impact. It has been proven possible to substitute 40% of the cement with inert materials, without significantly reducing the compressive stren…