Mechanical and structural properties of polyvinyl alcohol fibre reinforced concrete (PVA-FRC)

University of Technology, Sydney. Faculty of Engineering and Information Technology.Concrete is a brittle material that has low tensile strength and low strain capacity. In fact, many deteriorations and failures in the concrete structures are due to the brittle nature of this material (Hamoush et al. 2010). These disadvantages may be avoided by adding short discontinuous fibres to plain concrete which has been a major motivation for many research works in recent years (Wu & Sun 2003). Fibres are added into a brittle-matrix composite to help improve three major aspects; toughness, ductility and strength (tensile) (Arisoy 2002). Fibres tend to increase toughness of the composite material by bridging the cracks and provide energy absorption mechanism related to de-bonding and fibre pull-out. Furthermore, they can increase the ductility of the composite by allowing multiple cracking. They may also help increase the strength by transferring load and stresses across the cracks. Advancement of fibre reinforced concretes (FRCs) started in the 1970s. By that time, only glass fibre and steel fibre were investigated (Perumalsamy & Surendra 1992). Synthetic fibres have become more attractive in recent years as reinforcements for cementitious materials. This is due to the fact that they can provide inexpensive reinforcement for concrete and if the fibres are further optimized, greater improvements can be gained without increasing the reinforcement costs (Li et al. 1991; Wang et al. 1989). Moreover, unlike the steel fibre which is highly corrosive in nature, there is no corrosion concern regarding synthetic fibres in concrete. During the past 20 years (since early 1990s), polyvinyl alcohol (PVA) fibre has been introduced in the production of cementitious composites (Li 1998; Redon et al. 2001; Shen et al. 2008; Sun & Wu 2008). PVA fibres act greatly in a cement based matrix with no coarse aggregates due to their surface formation and high strength (Li et al. 2001). The resulting composite, which exhibits a pseudo ductile behaviour, is called engineered cementitious composites (ECC). Although many research works have been performed to date on the properties of PVA fibre reinforced ECC, there has not been much investigation on the mechanical and structural characteristics of PVA fibre reinforced concrete. Accordingly, the objective of this study is to experimentally observe the effects of adding PVA fibres to the conventional concrete to assess its mechanical and structural properties. To achieve this aim, a comprehensive set of experiments were carried out to investigate the effect of PVA micro fibre addition on mechanical and structural properties of conventional concrete. Therefore, concrete mixes containing PVA fibres of varying lengths (6 and 12 mm) in different fibre volume fractions ranging from 0.125% - 1% were prepared and tested for their fresh and hardened properties. The optimum fibre contents in terms of FRC performance were then selected to cast several concrete beams. These beams have later been tested for 4-point monotonic and 3-point cyclic flexure, to assess their structural properties. Hammer test was also conducted to evaluate the dynamic characteristics of conventional and FRC specimens as well as concrete beams

Flexural toughness and ductility characteristics of polyvinyl-alcohol fibre reinforced concrete (PVA-FRC)

This paper presents the results of an experimental study investigating the effect of un-coated polyvinyl alcohol (PVA) fibres on the properties of hardened concrete. PVA fibre of varying lengths, 6 and 12 mm and aspect ratio (l/d) of 430 and 860, respectively, was utilised in different volume fractions of 0.125%, 0.25%, and 0.5%. In addition, 30% fly ash was also used as partial replacement of Portland cement in all fibre reinforced concrete (FRC) mixes. Uniaxial compression, splitting tensile, modulus of rupture (MOR) and modulus of elasticity (MOE) tests were performed following the Australian Standards to evaluate the mechanical properties of PVA-FRCs. Fracture test is also conducted in accordance with European Standard in order to evaluate the residual flexural tensile strength and limit of proportionality of PVA-FRCs. Furthermore, the structural properties of reinforced concrete (RC) beams incorporating PVA fibres are investigated for their load-deflection behaviour using 4-point loading. Flexural toughness of the test specimens and peak load deflection were measured and discussed indicating to what extent the un-coated PVA fibre can enhance the brittle-like behaviour of concrete. Results show that adding PVA fibres to the mix generally improves the mechanical properties of concrete. Regarding the strength, the optimum fibre content goes to 0.25% for both fibre lengths and in the case of toughness and ultimate deflection 0.5% shows the highest values. An increase of 30% in ductility is noted for the RC beam incorporating 0.5% by volume fraction of 12 mm PVA fibre

Vibration Briquetting of Ash of Combined Heat and Power Plant

Ash and slag materials of combined heat and power plant (CHPP) are a unique resource that can be successfully used in construction, road and agricultural industries. However, their industrial use is accompanied with significant organizational and technical problems. Granulation of coal ashes improves the conditions of their storage and transportation, allows mechanizing and automating the subsequent use, increases productivity, improves the working conditions and reduces the loss of raw materials and finished products. This paper proposes a method of compacting of Seversk CHPP (Russia) ash by vibration briquetting using a number of binders (polyvinyl alcohol, glyoxal, liquid sodium glass). The main characteristics of Seversk CHPP ash such as chemical composition, particle size distribution, bulk density, content of unburnt carbon and radioactivity have been determined. Investigation of the effect of binder concentration on the static strength of granules revealed that the increase of binder concentration results in the growth of static strength of the dried granules that reaches a maximum at the concentration of 10 wt %: 0.28 MPa for polyvinyl alcohol, 0.63 MPa for glyoxal and 0.40 MPa for liquid sodium glass

Static mechanical properties of polyvinyl alcohol fibre reinforced concrete (PVA-FRC)

This investigation assessed the performance of polyvinyl alcohol (PVA) fibres of 6 mm and 12 mm length in concrete. Based on total concrete volume, four fibre fractions (0.125, 0.25, 0.375 and 0.5%) were evaluated for their effect on fresh and hardened properties of PVA fibre reinforced concretes (PVA-FRCs). Fly ash was also used as partial replacement of Portland cement in all the mixes. By carrying out a comprehensive set of experiments (compressive strength, splitting tensile strength, modulus of elasticity, modulus of rupture and residual flexural strength), it was observed that PVA fibre significantly enhances the static mechanical properties of concrete as well as improving its post-peak response and ductile behaviour

Prediction model for hardened state properties of silica fume and fly ash based seawater concrete incorporating silicomanganese slag

Growing concrete consumption has gradually depleted conventional resources. This research incorporates silicomanganese (SiMn) slag, marine sand and seawater as alternative concreting materials. The use of SiMn slag to replace limestone as coarse aggregate enhances sustainability, though reducing strength and durability of concrete. This research aims to enhance the SiMn slag concrete by incorporating silica fume (SF) and fly ash (FA). The interaction of SF and FA on strength, durability and workability of concrete is investigated by statistically evaluating the experimental result. In this regard, the polynomial function prediction model is developed using the Response Surface Method (RSM) for the optimization of SF and FA contents. Analysis of variance (ANOVA) using p-value at significance level of 0.05 showed that the models were statistically significant and had marginal residual errors. All models had high fitness with R2 value ranging from 0.853 to 0.999. Adequate precision of models was above 4, indicating that the models had a low prediction error and were fit for optimization. Optimization indicated that a combination of 11.5% SF and 16.3% FA produced concrete that met the optimization criteria. Experimental validation showed that the highest prediction error was 3.4% for compressive strength, 3.2% for tensile strength, 4.9% for sorptivity and 18% for chloride permeability. The optimized concrete exhibited compact microstructure with good bonding between aggregate and cement paste. By using the established linear equation with SiMn slag concrete, the models also predicted the compressive strength of limestone concrete containing SF and FA with an error of between 0.9% and 5.4%

Recent progress in low-carbon binders

The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements

Attraction and Electrophysiological Response to Identified Rectal Gland Volatiles in Bactrocera frauenfeldi (Schiner)

Bactrocera frauenfeldi (Schiner) (Diptera: Tephritidae) is a polyphagous fruit fly pest species that is endemic to Papua New Guinea and has become established in several Pacific Islands and Australia. Despite its economic importance for many crops and the key role of chemical-mediated sexual communication in the reproductive biology of tephritid fruit flies, as well as the potential application of pheromones as attractants, there have been no studies investigating the identity or activity of rectal gland secretions or emission profiles of this species. The present study (1) identifies the chemical profile of volatile compounds produced in rectal glands and released by B. frauenfeldi, (2) investigates which of the volatile compounds elicit an electroantennographic or electropalpographic response, and (3) investigates the potential function of glandular emissions as mate-attracting sex pheromones. Rectal gland extracts and headspace collections from sexually mature males and females of B. frauenfeldi were analysed by gas chromatography-mass spectrometry. Male rectal glands contained (E,E)-2-ethyl-8-methyl-1,7-dioxaspiro [5.5]undecane as a major component and (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane as a moderate component. Minor components included palmitoleic acid, palmitic acid, and ethyl oleate. In contrast, female rectal glands contained (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane and ethyl laurate as major components, ethyl myristate and ethyl palmitoleate as moderate components, and 18 minor compounds including amides, esters, and spiroacetals. Although fewer compounds were detected from the headspace collections of both males and females than from the gland extractions, most of the abundant chemicals in the rectal gland extracts were also detected in the headspace collections. Gas chromatography coupled electroantennographic detection found responses to (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane from the antennae of both male and female B. frauenfeldi. Responses to (E,E)-2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecane were elicited from the antennae of females but not males. The two spiroacetals also elicited electropalpographic responses from both male and female B. frauenfeldi. Ethyl caprate and methyl laurate, found in female rectal glands, elicited responses in female antennae and palps, respectively. Y-maze bioassays showed that females were attracted to the volatiles from male rectal glands but males were not. Neither males nor females were attracted to the volatiles from female rectal glands. Our findings suggest (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane and (E,E)-2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecane as components of a sex-attracting pheromone in B. frauenfeldi

FLEXURAL AND TENSILE CHARACTERISTICS OF POLYVINYL ALCOHOL FIBRE REINFORCED CONCRETE (PVA-FRC)

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan

INFLUENCE OF POLYVINYL ALCOHOL FIBRE ADDITION ON FRESH AND HARDENED PROPERTEIES OF CONCRET

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan

DAMPING PROPERTIES OF POLYVINYL ALCOHOL FIBRE REINFORCED CONCRETE

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan