Use of waste paper ash or wood ash as substitution to fly ash in production of geopolymer concrete

Large quantities of paper and wood waste are generated every day, the disposal of these waste products is a problem because it requires huge space for their disposal. The possibility of using these wastes can mitigate the environmental problems related to them. This study presents an investigation on the feasibility of inclusion of waste paper ash (WPA) or wood ash (WA) as replacement materials for fly ash (FA) class F in preparation geopolymer concrete (GC). The developed geopolymer concretes for this study were prepared at replacement ratios of FA by WPA or WA of 25, 50, 75 and 100% in addition to a control mix containing 100% of FA. Sodium hydroxide (NaOH) solutions and sodium silicate (Na2SiO3) are used as alkaline activators with 1M and 10M of sodium hydroxide solution.The geopolymer concretes have been evaluated with respect to the workability, the compressive strength, splitting tensile strength and flexural strength. The results indicated that there were no significant differences in the workability of the control GC mix and the developed GC mixes incorporating WPA or WA. Also, the results showed that, by incorporating of 25–50% PWA or 25% WA, the mechanical properties (compressive strength, splitting tensile strength and flexural strength) of GC mixes slightly decreased. While replacement with 75–100% WPA or with 50–100% WA has reduced these mechanical properties of GC mixes. As a result, there is a feasibility of partial replacement of FA by up to 50% WPA or 25% WA in preparation of the geopolymer concrete.

Removal of Meropenem by using Lemna minor

In this paper we presented a case study about the removal of a pharmaceutical contamination (in this case Meropenem) from the environment using organic natural substance (in this case study is Lemna minor). The study proved the efficiency of the used material to remove the contamination of three specific contamination levels of Meropenem. The experimental testing proved the concept, the effect on two vital measures (the chemical oxygen demand – COD, and the root length), which showed improvement in both measures. The degradation mechanism was proven to be not arbitrary by testing the degradation behavior measured practically to four kinetic models. The practical work was found to fit perfectly with the Grau second order model as the simulation work included in the paper shows. Based on this study it can be proven that the dangerous chemicals resulted from the residue of a pharmaceutical substances can be removed efficiently using a totally natural environmental friendly material.

Mesoscale modeling of fracture in cement and asphalt concrete

In this paper, mesoscale modeling is performed to simulate and understand fracture behavior of two concrete composites: cement and asphalt concrete using disk-shaped compact tension (DCT) tests. Mesoscale models are used as alternative to macroscale models to obtain better realistic behavior of composite and heterogeneous materials such as cement and asphalt concrete. In mesoscale models, aggregate and matrix are represented as distinct materials and each material has its characteristic properties. Disk-shaped compact tension test is used to obtain tensile strength and fracture energy of materials. This test can be used as a better alternative to other tests such as three points bending tests because it is more convenient for both field and laboratory specimens in addition to its accurate results. Comparing the numerical results of the mesoscale models of cement and asphalt concrete specimens with experimental data shows that these models can predict the behavior of these composite materials very well as seen in the curves of load-crack mouth opening displacement (CMOD). Also, the mesoscale modeling highlights the variability of crack direction where it is dependent on the random distribution of aggregate.

Sustainable acoustic insulation for prefabricated concrete homes in Andean zones

The construction sector is undoubtedly one of the main promoters for economic and social development. The modern concept of the prefabrication of elements originated from the industrial revolution to reduce costs and increase production through the mechanization of work, increasing the quality and ease of control in the plant. Prefabricated concrete homes are aimed at the popular sectors, however, when talking about acoustic habitability comfort we refer to constructive solutions used in a building to minimize the transmission of sounds (noise pollution) from outside or from an adjoining enclosure. This is achieved with the use of acoustic insulation materials. In the present research, through a bibliographic review, the updated state-of-the-art search methodology is developed, supported by the Delphi and AHP (hierarchical analytical process) methods and with the opinion of experts to compare the properties of acoustic insulating materials; in order to publicize the best acoustic insulators to be installed inside prefabricated concrete homes. Within the bibliographic review, new technologies with sustainable materials found as feasible prototypes were investigated in Ecuador, where thanks to its diversity of ecosystems and the necessary existing technology, the natural fibers used in the prototypes for insulation/absorption are easily found acoustics in homes.

Operation and maintenance financial feasibility analysis of centralized domestic wastewater treatment system (case study: Palembang City Sewerage Project)

Budget needed for operation and maintenance of centralized domestic wastewater management in Indonesia is often overlooked. This results in fail systems, high idle capacity, and abandoned assets. While the economic feasibility often used as the basis for centralized domestic wastewater infrastructure construction, the financial feasibility often shown a different result. The construction phase will be feasible according the analysis, while the operation and maintenance phase will have a different result. As unsolicited projects, the operation and maintenance of sewerage in Indonesia always have budget difficulties, thus needed scenario to resolve the matter. In this study, cost and revenue variable will be analyzed to determine the feasibility value based on NPV, BCR, and IRR calculations. The revenue comes from user charge tariffs on household and commercials connections, and cost variable consists of: chemical usage cost; sludge disposal cost; personnel wage cost; fuel and electricity cost; spare-part replacement cost. The analysis will determine whether both household connection and commercials connection in the sewerage system have positive results. Should negative results emerged, follow up analysis added to elevate the results consists of following scenarios: sensitivity analysis for tariffs adjustment; sensitivity analysis adding grant as option; sensitivity analysis adding loan as option. While analysis of base tariffs shown negative results on NPV, BCR, and IRR calculation, the follow up analysis shown significant changes thus the results is desirable.

Relation between CO2 emissions and crude oil combustion in Iraq

Fossil fuel is the main source for CO2 emissions that causes global warming. This fact is the starting point for this paper, that consider on three different sources of data: crude oil used to calculate CO2 emissions for Iraq for the period from 1980 to 2018; annual data of total CO2 emissions available from the Carbon Dioxide Information Analysis Center (CDIAC) for Iraq and the world for the period from 1980 to 2014; and CO2 concentrations for Iraq for the period from 2002 to 2006 and for the world for the period from 1980 to 2018. The result is a multifaceted according to the dataset sources. Carbon dioxide emissions calculated from Iraqi crude oil was increased from 1.29 Mt in 2012 to 1.97 Mt in 2018. The world and Iraq CO2 emissions with different slop of average line that was 0.5 for world, 0.003 for Iraq, while increased exponential function from 2008 to 2014 to reach 36 and 0.17 Mt, respectively. The highest value of Iraqi CO2 concentration was 403 ppm in 2016, while the global CO2 concentrations slowly increased with slop line equal to 1.75 ppm per year, from minimum value of 338.6 ppm was in 1980, while maximum value of 407.05 ppm was in 2018, that’s mean no decreased in CO2 concentration unless emissions addressed.

Investigation the effect of newly used polymer modified bitumen on the performance of hot mix asphalt containing reclaimed asphalt pavement

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value.

Strength of eccentrically tensioned reinforced concrete structures with small eccentricities by normal sections

It is implemented the method of normal rectangular sections slab (shell) reinforced concrete elements strength calculating with flat eccentric tensile strength using the deformation m ethod. The results of the calculation are analyzed for the case of eccentric tension with small eccentricities with varying next parameters: the height of the cross section and the reinforcement coefficient. It is investigated the character of diagrams condition change of section “N – εc(1)” at gradual change of the stress-strain state from eccentric to the central tension. It is revealed that when the eccentricity of external forces decreases, the compressed zone of concrete decreases until its complete disappearance, and at rather small values of eccentricities of force application the balance between external and internal forces cannot be found by the method of current norms. An equilibrium is found between internal and external forces only at a two-digit diagram of the distribution of relative longitudinal deformations (in the case of a compressed zone). Variants of the given problem decision without considerable loss of calculations accuracy are offered, the most expedient of which is transition to algorithm of calculation by a method of limiting efforts. It was accepted as the basic in the previous building norms. The results of numerical calculations performed in the software complex “Lira-CAD” and the corresponding mathematical modeling confirmed the rationality and allowable accuracy of further calculations by this method.

Detecting the relations between meteorological elements and alpha and beta activity concentration at Al-Tuwaitha site, Baghdad

In this study, 50 samples of air particulates collected from different places in- and outside the Al-Tuwaitha nuclear site, south of Baghdad were used to measure daily gross alpha and beta activity concentrations (AAC and BAC) for the period from 28 January 2015 to 13 April 2017. At the same time, several meteorological factors such as air temperature, wind speed, wind direction, air pressure, relative humidity, and solar radiation, were also measured. Air stability classes were also derived from wind speed and solar radiation. AAC/BAC variations in the surface air layer were discussed in relation to these factors. The results show that there are inverse relations between AAC/BAC and wind speed and temperature, linear relations between AAC/ABC and air pressure and weak relations between AAC/BAC and relative humidity and solar radiation. Lastly, AAC/BAC measurements in unstable air are as large as in neutral air.

Longitudinal shear in composite deck slabs using corrugated steel sheets

Profile deck steel sheets are used in composite deck slabs. These sheets are standard in dimensions and shapes besides they are supplied with embossments and indentations. Such sheets are not available in Iraqi markets nowadays therefore people used another type of sheets which are corrugated without embossments or indentations in very wide range. This study covers the use of such sheets in composite slabs as decks instead of standard profiled steel sheets. The study comprises testing slabs of dimensions 0.9 × 2.5 m reinforced by steel fabric mesh and rested on corrugated sheets. Two types of shear spans are selected shorter and longer to study the longitudinal shear force transmitted due to the applied loads according to the Eurocode 4. The shorter shear spans are 600, 500 and 400 mm while longer one is 800, 750 and 700 mm. The study extended to support the requirements of design equation of the Eurocode by shear bond method also known as m–k method. The evaluated values of m and k are 0.094 and 65 respectively. The result of k which plays a very important role in shear transfer is small compared to what available in literature, therefore it is recommended to make use of shear connectors in such construction or any else method.