Comparing flexural behaviour of fibre-cement composites reinforced bagasse:wheat and eucalyptus

In this paper the applications of Agricultural Waste Fibres (AWF) are considered in producing the Fibre Cement Boards (FCB). Three different AWFs including bagasse, wheat and eucalyptus fibres as 2% and 4% by the weight of Portland cement, were used to produce FCB. Moreover, the effect of silica fume on flexural behaviour characteristics of FCB has been studied. The results show that the flexural behaviour of the FCBs depends on the type, length, diameter, aspect ratio and texture of fibres. Also for all groups with increasing fibre content from 2% to 4% of cement weight, maximum flexural strength increases. Moreover, silica fume could improve the flexural strength for all the groups

Scrap-tyre-rubber replacement for aggregate and filler in concrete

In this research the performance of concrete mixtures incorporating 5%, 7.5% and 10% of discarded tyre rubber as aggregate and cement replacements was investigated. Numerous projects have been conducted on replacement of aggregates by crumb rubbers but scarce data are found on cementitious filler addition in the literature. Hence to examine characteristics of tyre crumb-containing concrete, two sets of concrete specimens were made. In the first set, different percentages by weight of chipped rubber were replaced for coarse aggregates and in the second set scrap-tyre powder was replaced for cement. Selected standard durability and mechanical test were performed and the results were analysed. The mechanical tests included compressive strength, tensile strength, flexural strength and modulus of elasticity. The durability tests included permeability and water absorption. The results showed that with up to 5% replacement, in each set, no major changes on concrete characteristics would occur, however, with further increase in replacement ratios considerable changes were observed

The density and distribution of the dominant phytoplankton in the southern Caspian Sea

The research project was comprised of four sampling cruises, which were carried out in summer 94; spring, autumn and winter 95 in the southern part of the Caspian Sea, where Chrysophyta (Diatoms) and Pyrrophyta were found to be the dominant phytoplankton. The maximum density of phylum Chrysophyta (Diatoms) was observed mainly during the autumn in the coast line (below 20 m) and in the central part of the southern Caspian Sea, while the highest density of phylum Pyrrophyta occurred during the spring in the subcoastal zone (below 50 m.). The dominant species in the phylum Chrysophyta (Diatoms) were Rhizosolenia calcar-avis, Thalossionema nitzschiodes, Sceletonema costatum, Cyclotella meneghiniane and three members of genus Coscinodiscus, among which R. calcar-avis had the highest density. Members of phylum Pyrrophyta, i.e. Exuvialla cordata, Prorocentrum scutellum and Glenodinium penardii had the highest density during the spring in the central part of the southern Caspian Sea, where E. cordata was the most abundant

Using ground granulated blast-furnace slag and mineral wastes to reduce cement in paving block

Portland cement production releases carbon dioxide; this has significant adverse effects on the environment and so a reduction in the content of Portland cement in concrete products will improve the carbon footprint. This investigation explored the use of by-product materials and waste in the production of paving blocks. The following materials were examined: ground granulated blast-furnace slag, basic oxygen slag, plasterboard gypsum and cement by-pass dust. Ternary blends were created for different mixes and tested. The tensile strength, skid/slip resistance and freeze/thaw of each paving block specimen were determined in accordance with British Standard BS EN 1338. It was found that about 30% cement replacement was achieved in comparison with current factory production in the UK without having any considerable impact on the strength and durability of the paving blocks. It was also found that a cement mix can contain ground granulated blast-furnace slag up to 55%, basic oxygen slag up to 70%, cement by-pass dust up to 10% and plasterboard gypsum up to 5% by weight

The impact of variation in chemical and physical properties of PFA and BPD semi-dry cement paste on strength properties

The effect of Pulverised Fuel Ash (PFA) and By-Pass-Dust (BPD) in ternary semi-dry cement pastes was reported. As well as this, the variability over 6 months in chemical composition and particle distribution was reviewed to determine impact on strength. The addition of BPD in ternary pastes resulted in a reduced strength when combined with PFA. PFA and BPD samples obtained over a 6 month period showed variability in both chemical composition and particle distribution. For PFA, it was reported that at 14 days the particle size distribution had greatest impact on strength and at 28 days the SiO2 content had greatest impact. The high variability in BPD particle size distribution resulted in finer particles achieving the greatest strength

Potential for carbon dioxide reduction from cement industry through increased use of industrial pozzolans

Concrete is the most widely used material on earth, eclipsing the combined volumes of all other man made materials by a factor of ten. In terms of its embedded carbon, it is a benign product, being associated with relatively little CO2 per unit mass when compared with metals, glasses and polymers. Conversely, it is made in such vast quantities, that it is responsible for over five percent of anthropogenic CO2. Despite recent advances in kiln design and alternative, low energy clinkers, it seems likely that the greatest carbon savings from the industry are likely to be made by the inclusion of supplementary cementing materials. This article reviews some of the options currently under investigation, especially from the UK perspective, and highlights that some of the research needs to be satisfied before such materials are more widely adopted

An investigation on the critical success factors of total quality management implementation in Libyan construction organisations

The paper presents an investigation on the Critical Success Factors (CSFs) of the implementation of Total Quality Management (TQM) in Libyan construction organisations. A thorough review of literature has been carried out to identify the CSFs, which were then used to develop a questionnaire. Of 200 questionnaires distributed to contractors in Tripoli, 130 were completed and returned, representing a response of 65 per cent. Among of these participating organisations about two-third are from the public sector, and the rest from the private sector. The data were analysed using Principal Component Analysis (PCA) which revealed the internal structure of the data in a way which best explains the relationships between CSFs. The findings identified five reliable and valid TQM constructs, namely ‘organisation management’, ‘communication to improve quality’, ‘training and development’, ‘employee’s involvement and recognition’ and ‘culture’. The findings revealed a low level of CSFs implementation, which might be originated from little understanding of the fundamental TQM principles

Hydrology and hydrobiology data analysis collected during 1998-2007

Annually, many data of hydrology and hydrobiology of the southern Caspian Sea at Iran's coasts were collected by Caspian Sea Research Institute of Ecology. The data which had been collected by researchers submitted annually in several reports but has not been processed all at once. Fluctuations of various parameters were surveyed and the relationships between them were analyzed. The main goal of this research is to analysis the data were obtained from 1994 to 2006 and show changes the concentration of various parameters in the Caspian Sea. Physicochemical data indicated that the average trend of transparency and salinity was decreased from 1994 to 2006 annually, where the salinity value was decreased from 12.37 ppt (part per thousand) to 11.5 ppt. The average of dissolved oxygen was increased from 6.4 to 8.6mg/l. pH has slightly fluctuated from 8.15 to 8.31. However, with increasing depth from surface to bottom, the average of dissolved oxygen was sharply decreased (DO concentration in surface and 800 m was 7.18 and 1.45 mg/l, respectively). The trend of salinity and pH fluctuation was very slow with depth but the salinity has an increasing with incrementing of depth but pH has a decreased trend. The average of organic and inorganic phosphorus and TP was nearly increased. The average of Nitrate and Silica sharply increased comparing to depth but the average of Nitrite and organic Nitrogen decreased. The results showed that the temperature fluctuation in different water layers was low in winter but the dramatic decreasing of temperature was occurred at 10-20 m (in spring), 20-50 m (in winter) and 50-100 m (in autumn). With increasing of depth (Slope of the Sea), transparency and salinity values have an increasing while DO and pH showed decreased. As a whole, 335 species of phytoplankton were identified, there are 70 species in advance as these species were not seen in this period but 96 of novel's species have been recorded. The lowest and the most of phytoplankton biomass was recorded in 2006 and 2001 while the biomass was 59 and 1034 mg/m^3, respectively. Albet, the lowest biomass was recorded at the depth of 100 m (24.1 mg/m^3) but the maximum was observed in surface layer (1344.1 mg/m^3). The average of phytoplankton biomass was increased after arrival of the ctenophore. There was a significant difference between the average of biomass in different seasons before and after of the ctenophore invasion (P0.137, P>0.782). Before the presence of ctenophore, the worms had been constituted a dominate group with an approximately %45 of total abundance and also %20 of their biomass. After this period, their frequency was sharply increased (more than %85) but the maximum value pertains to Cardidae (more than %90). The species diversity, evenness and richness were varied between .69-2.51, 0.23-0.63 and .011-3.79, respectively. AMBI software, Shanon-Viner parameter was moderate in all seasons from 1994 to 1996 but this parameter was reduced in a bad limit (boundary) in the most seasons from 2002 to 2005. The main parameter of M-AMBI consists of several parameters and also approximately showed similar changes such as Shanon -viner parameter. On basis of this parameter, the ecological quality condition of Caspian Sea was superior limit in all seasons from 1994 to 1996 but after the following years were decreased from good to moderate limits (After the presence of ctenophore). Relationship between abiotic variants and phytoplankton indicated that there was a direct relationship between transparency and salinity while there was a powerful and reversal significant relationship between transparency water temperature, transparency in organic Nitrate, phytoplankton number and transparency phytoplankton biomass. The comparison between different variants average in two periods (before and after the ctenophore invasion) indicated that the average of Kilka catch was decreased, the relative frequency of clupeonella engrauliformis and clupenoella grimmi was sharply reduced but the relative frequency of Clupeonella cultriventris was sharply increased, the species diversity, evenness and richness and the number of zooplankton species were sharply decreased, the average of biomass and transparency was sharply reduced, the average of dissolved oxygen and liza saliens or liza auratus catch were increased. These difference were often significant (P<0.05). Therefore, with the ctenophore invasion into the Caspian Sea, the primary production was increased, the biomass value of zooplankton and specially Kilka which fed on zooplankton were sharply decreased while the fish such as Rutilus frisii kutum and mullet (Liza salins or Liza aurratus) which fed on benthic were increased

Study on environmental of Litopenaeus vannamei (Boone, 1931) ponds culture with brackish water of Caspian Sea

Different studies on Litopenaeus vannamei (Boone, 1931) has performed in Iran, but less noted in water quality conditions. Water quality, in addition to creating optimal environment for the growth of vannamei shrimp, as well as cause the live food production and improve economic performance are produced. This study was conducted to evaluate the water quality environment vannamei shrimp in the south of Caspian Sea (Mazandaran province) and in the Caspian Ecology Research Center. The results showed that the enrichment of water out of the ponds, can provide favorable conditions for water quality in the culture of vannamei shrimp with different densities. As a result, Mazandaran province environmental conditions (particularly temperature and salinity of the Caspian Sea) has perfectly suited for optimal growth vannamei shrimp. Therefore, vannamei shrimp (PL12) achieved a final individual weight of 21.1gr in a period culture of 85-day with a density of 35 ind/m^2. Also, The nutrients and water quality parameters (Temperature: 27.4±1.79 ° C, Transparency: 10.7±1.2 cm, Salinity: 10.57±0.78 psu, pH: 8.42±0.38, Dissolved Oxygen 8.04±1.35 mg per liter) were within normal limits during the culture period