Exploitation of solid waste in foamed concrete challenges ahead

This paper reviews the contribution of some researchers on blended cement and reports recent findings of a research programme focused on the exploitation of solid wastes in foamed concrete. Solid wastes studied include rice husk and its derivatives, paper sludge and recycled expanded polystyrene (EPS). The objective is to develop an environmental-friendly and economical foamed concrete for construction. A novel process for the synthesis of micronised silica for use in foamed concrete is revealed in order to provide a unique solution to construction on soft soil. Concerted collaborative effort by researchers and the readymix concrete industry is expected to enhance the competitive edge of the construction industry

Timber-Concrete Composite Floor Beams under 4 Years Long-Term Load

The long-term behaviour of timber-concrete composite is characterized by the response of its three components (timber, concrete and connection) to load, moisture content, temperature and relative humidity of the environment. This paper reports results of a 4-years long-term test on three 8m span laminated veneer lumber (LVL)-concrete composite floor beams under service load performed in an indoor, uncontrolled, and unheated environment at the University of Canterbury. The environmental conditions were characterized by either low temperature with high relative humidity or high temperature with low relative humidity, conditions considered to be reasonably severe and presumably close to service class 3 according to Eurocode 5. The mid-span deflections were extrapolated to the end of service life (50 years) and compared to span/200 deflection limit, which was exceeded by all beams

Performance of Recycled Aggregate Concrete Containing Micronised Biomass Silica

This paper presents a study on Micronised Biomass Silica (MBS) that was produced from the controlled burning of waste Rice Husk. The MBS was used as pozzolan material to enhance the performance of Recycled Aggregate Concrete (RAC). Various percentages by mass of Micronised Biomass Silica were applied in the normal and recycled aggregate concrete cube samples. Compressive strength and water permeability tested on the samples at the age of 7, 14, 28 and 90 days showed that concrete containing MBS has attained higher compressive strength. Furthermore, the test on MBS also showed its ability to enhance the concrete water permeability. Lengthen to this; the study established a good correlation between the MBS content with compressive strength and water permeability coefficient

Strength Behaviour Of Biomass Fiber-Reinforced Concrete Slab

This paper investigates the compressive strength and flexural strength of biomass fibre-reinforced concrete slab. The main objective of this study is to examine the effect of biomass aggregate and fibre glass on the concrete slab strength. The biomass aggregate is used to replace the natural aggregates. A total of 36 slab samples (250 mm x 600 mm x 50mm thick) and 36 numbers of 150 mm cube samples containing 0%, 30%, 60% and 100% biomass aggregate were prepared.  The E-class fibre and Supracoat SP800 were added to increase the strength and to achieve the required workability. All the samples were cured in water with room temperature of around 27oC and tested at the age of 7, 14 and 28 days respectively. The result showed that cube specimens containing 30% biomass aggregate concrete achieved minimum strength of 15 MPa at 28 days. The flexural strength for slab specimens containing 30% biomass aggregate, Supracoat SP 800 and fibre glass gained higher strength compared with control specimens. The 100% biomass aggregate slab achieved 88% of the control specimen strength. The workability was between 150 mm to 170mm slump. The density of the specimens was reduced 20% for cube and 28% for slab compared with control specimens. It can be concluded that the biomass aggregate has good potential as partial aggregate replacement in slab construction when combined with the use of glass fibre and superplasticizer. However, more research needs to be carried out to self-compacting biomass aggregate concrete for sustainable constructio

CO2 Uptake Model of Biomass Silica Foamed Concrete

The cement industry contributes about 5% to global anthropogenic CO2 emissions. CO2 isemitted from the calcination process of limestone, from combustion of fuels in the kiln, aswell as from power generation. A model of CO2 uptake by biomass silica foamed concrete isproposed as a potential mitigation strategy against CO2-emission. The key parameters in thecement production process are defined and the total CO2 emissions are reviewed. Acomparison between CO2 emission and CO2 uptake by carbonation is made. The forecastingof CO2 uptake by carbonation is modeled with the use of Microsoft Excel. The CO2 emissionmitigation options are discussed based on the modeling on CO2 uptake by biomass silicafoamed concrete. The proposed foamed concrete absorbs CO2 42.7% faster than the normalPortland cement concrete, with a regression accuracy of 0.98. Successful deployment couldcontribute towards sustainable development while benefiting from the carbon credits

WATER PERMEABILITY OF MICRONISED BIOMASS SILICA CONCRETE

Abstract Malaysia is a country which its citizens employe

Evolution of chemical abundances in Seyfert galaxies

We computed the chemical evolution of spiral bulges hosting Seyfert nuclei, based on updated chemical and spectro-photometrical evolution models for the bulge of our Galaxy, made predictions about other quantities measured in Seyferts, and modeled the photometry of local bulges. The chemical evolution model contains detailed calculations of the Galactic potential and of the feedback from the central supermassive black hole, and the spectro-photometric model covers a wide range of stellar ages and metallicities. We followed the evolution of bulges in the mass range 10^9 - 10^{11} Msun by scaling the star formation efficiency and the bulge scalelength as in the inverse-wind scenario for elliptical galaxies, and considering an Eddington limited accretion onto the central supermassive black hole. We successfully reproduced the observed black hole-host bulge mass relation. The observed nuclear bolometric luminosity is reproduced only at high redshift or for the most massive bulges; in the other cases, at z = 0 a rejuvenation mechanism is necessary. The black hole feedback is in most cases not significant in triggering the galactic wind. The observed high star formation rates and metal overabundances are easily achieved, as well as the constancy of chemical abundances with redshift and the bulge present-day colours. Those results are not affected if we vary the index of the stellar IMF from x=0.95 to x=1.35; a steeper IMF is instead required in order to reproduce the colour-magnitude relation and the present K-band luminosity of the bulge.Comment: 17 pages, 15 figures, 3 tables, accepted for publication in A&

Development of blended cements for water proofing application

The application of mineral admixtures as partial cement replacement in concrete leads to a reduction in construction cost. Usually single mixture has limitation and some have contrasting influences on properties of concrete. The combination of more kinds of mineral admixtures is postulated to improve concrete properties. Since RHA is highly reactive pozzolan, it has led to the idea of focusing the study on the performance of Multi-blended pozzolan as partial cement replacement in mortar. Over 8 different mixes were produced in which four mixes contained varying percentages of admixtures (Multi Blended Cement, MBC) and the remainders were single mix (Binary Blended Cement, BBC) containing optimum percentages (based on literature study) of 20% PFA, 20% RHA, 50% SLAG, and 10% POFA. Three samples for each mix, curing period and parameter tests were prepared. This work initially deals with compressive strength characteristics, water absorption, and total porosity on mortar cured (standard curing) for 7, 28, 60 and 90 days. The performance of optimum MBC mortar was studied in terms of ultimate compressive strength, water absorption and total porosity. The strength properties of the optimum mixes of MBC mortars was also examined at different curing regimes. This research also focuses on studying some durability aspects of the optimum mix of MBC mortars namely acid attack, and carbonation. Besides, the effects of saline seawater were investigated for short term exposure. Finally attempt in brief study on suitability of the optimum mixes of MBC mortars as face sheets to produce lightweight non-load bearing sandwich block was conducted. From the results obtained, it was found that the strength of control and BBC mortars at early age on average were 20% higher than MBC mortars, and at final age both were comparable with MBC mortars. The strength of all mortars at 90 days on average was 59MPa. However, the MBC system produced low permeability mortar compared to control, and BBC mortars at all ages. The total porosity and water absorption of control and BBC were 28% and 21%, and 9% and 14%, respectively. The strength of MBC mortar after 45 cycles of wet and dry curing in seawater exhibited 24% higher than control mortar. The initial water curing for 7 and 14 days and continuous air curing also exhibited 13% and 19%, and 21% and 26%, higher early strength than continuous water and air curing, respectively. The strength and durability properties of MBC mortar are more pronounced than control when it is provided with adequate curing. After exposure to chemical attack, the MBC mortar exhibits better resistance than control mortar. With adequate curing the MBC mortar was higher in durability than control mortar when subjected to chemical attack

Carbonation and Water Permeability of Foamed Concrete

This paper reports recent findings of a research programme focused on the carbonation and permeability of foamed concrete. The objective is to develop an environmentalfriendly and economical material for sustainable construction on peat. A four-year study showed that the rate of carbonation is related to the permeability, time and density. A water permeability test system has been developed based on ISO/DIS7031 and a draft standard prepared. They are aimed at promoting concrete durability research. It features a dual-test method for the measurement of water permeability with the standard 150 mm test cube prior to the determination of compressive strength. The calibration of the test system is by means of a mature test cube of known water permeability. The test system plays complementary role to the existing methods of assessing durability such as carbonation test and rapid chloride permeability. The test method is non-destructive, convenient and reliable for assessing concrete durability in the laboratory at the mix design stage. It can be used subsequently for tests on concrete products and structures for rain water harvesting system. Information technology has been experimented to provide online skill training and the electronic publications of research findings to promote good concrete practice via a concrete innovation blog http://www.1.net.my and a concreteresearch portal http://www.it-lodge.com