Unit Weight Research Articles

Performance Evaluation of Reclaimed Asphalt Pavement (RAP) Incorporated Concrete for Rigid Pavements

Abstract: The production of Reclaimed Asphalt Pavement (RAP) has seen a recent increase, and Pakistan's road network spans almost 100,000 kilometers, with almost 30% of RAP able to be produced from it. This study aimed to explore the use of RAP as an aggregate in rigid pavements. Virgin coarse aggregate (VCA) was partially or completely replaced with RAP at ratios of 0, 25, 50, 75, and 100%. A mix design was carried out to achieve 4000psi, and fresh concrete specimens were cast and tested for slump, temperature, and unit weight. After 28 days of curing, some of the hardened concrete specimens were tested for compression and tensile strength using a Universal Testing Machine (UTM) machine, while flexural tests were conducted on beams. The modulus of adaptability was calculated using UCAM programming with the help of a data logger. The results indicated that compressive, flexural, and splitting tensile strength reduced with an increase in RAP content. However, the modulus of elasticity plots shows that while the stiffness decreased with an increase in RAP content, ductility shows a slight improvement. Based on the findings, replacing up to 25% of VCA with RAP was considered the best permissible replacement in rigid pavement, offering maximum performance. Additionally, a cost analysis of RAP showed a 71% cost saving in VCA and 3% overall section cost saving by replacing just 25% of RAP.

The limits of local search for weighted k-set packing

We consider the weighted k-set packing problem, where, given a collection S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {S}}$$\\end{document} of sets, each of cardinality at most k, and a positive weight function w:S→Q>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$w:{\\mathcal {S}}\\rightarrow {\\mathbb {Q}}_{>0}$$\\end{document}, the task is to find a sub-collection of S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {S}}$$\\end{document} consisting of pairwise disjoint sets of maximum total weight. As this problem does not permit a polynomial-time o(klogk)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$o(\\frac{k}{\\log k})$$\\end{document}-approximation unless P=NP\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P=NP$$\\end{document} (Hazan et al. in Comput Complex 15:20–39, 2006. https://doi.org/10.1007/s00037-006-0205-6), most previous approaches rely on local search. For twenty years, Berman’s algorithm SquareImp (Berman, in: Scandinavian workshop on algorithm theory, Springer, 2000. https://doi.org/10.1007/3-540-44985-X_19), which yields a polynomial-time k+12+ϵ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{k+1}{2}+\\epsilon $$\\end{document}-approximation for any fixed ϵ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon >0$$\\end{document}, has remained unchallenged. Only recently, it could be improved to k+12-163,700,993\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{k+1}{2}-\\frac{1}{63,700,993}$$\\end{document} by Neuwohner (38th International symposium on theoretical aspects of computer science (STACS 2021), Leibniz international proceedings in informatics (LIPIcs), 2021. https://doi.org/10.4230/LIPIcs.STACS.2021.53). In her paper, she showed that instances for which the analysis of SquareImp is almost tight are “close to unweighted” in a certain sense. But for the unit weight variant, the best known approximation guarantee is k+13+ϵ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{k+1}{3}+\\epsilon $$\\end{document} (Fürer and Yu in International symposium on combinatorial optimization, Springer, 2014. https://doi.org/10.1007/978-3-319-09174-7_35). Using this observation as a starting point, we conduct a more in-depth analysis of close-to-tight instances of SquareImp. This finally allows us to generalize techniques used in the unweighted case to the weighted setting. In doing so, we obtain approximation guarantees of k+ϵk2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{k+\\epsilon _k}{2}$$\\end{document}, where limk→∞ϵk=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lim _{k\\rightarrow \\infty } \\epsilon _k = 0$$\\end{document}. On the other hand, we prove that this is asymptotically best possible in that local improvements of logarithmically bounded size cannot produce an approximation ratio below k2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{k}{2}$$\\end{document}.

Deep Neural Network Model for Determination of Coal Cutting Resistance and Performance of Bucket-Wheel Excavator Based on the Environmental Properties and Excavation Parameters

In the present paper, we develop a new model, based on the implementation of deep neural networks, for the estimation of a series of excavation parameters, depending on the main environmental and excavation properties. The developed model, with high statistical accuracy (R > 0.79) and small RMSE (<17% of the actual output values), enables the simultaneous assessment of the following excavation parameters: effective capacity Qef, maximum current consumption Imax, maximum power consumption Nmax, maximum force consumption Pmax, maximum energy consumption Emax, and maximum linear and areal cutting resistance, KLmax and KFmax, respectively, based on the impact of the following environmental properties and excavation parameters: coal unit weight, coal compression strength, coal cohesion, friction angle, excavator movement angle in the left and right direction, slice height and thickness, and wheel velocity. The data analyzed in the present paper were previously collected from three neighboring open-pit coal mines in Serbia: Tamnava Western Field, Tamnava Eastern Field, and Field D. These mines have similar geological conditions and coal properties. Additionally, for each output factor, a complex analysis is provided on the impact of the examined input factors, by applying the multiple linear regression method. As far as we are aware, this is the first time such a comprehensive estimation model has been suggested for the operation of a bucket-wheel excavator in the Neogene coal basins. The deep neural network (DNN) model, trained over 300 epochs, shows an MSE range of 6.7–16.5% across various input factors, with distinct evaluations for Imax due to its unique values (4.8–12.5%).

Cement mortar composites including 1-tetradecanol@PMMA Pickering emulsion particles for thermal energy management of buildings

In this study, a poly(methyl methacrylate) (PMMA) shell 1-tetradecanol core microencapsulated phase change material (MPCM) was produced using the Pickering emulsion technique. Characterization tests of the produced MPCMs were performed using Fourier transform infrared (FT-IR) spectroscopy, particle size distribution (PSD) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques. The latent heat, melting temperature and encapsulation rate of MPCM were determined and they were found as 108.4 J/g, 33 °C, and 46.7 % for heating period, respectively. The effect of 1-tetradecanol@PMMA MPCM on the physical, mechanical, and thermal performance properties of cementitious mortars was also investigated in the study. For this reasons 1-tetradecanol@PMMA MPCMs are included in mortar mixes at 5 %, 7.5 %, and 10 % by weight of cement. As the MPCM ratio increased, the water absorption rate and porosity increased, while the workability, unit weight of the mortar, ultrasonic pulse velocity, flexural strength and compressive strength parameters decreased. The compressive strength of the mortar containing 10 % MPCM on the 28th day was measured as 34.74 MPa. The highest thermal storage capacity was found in mortars containing 10 % MPCM. When the thermal performance of the reference and 10 % MPCM-containing mortars were compared, the indoor temperature differences at the end of the heating and cooling periods were measured as 4.7 °C and 3.9 °C, respectively. The results showed that MPCM produced by the Pickering emulsion technique has the potential to increase thermal comfort in buildings, reduce fuel consumption used for heating purposes and, accordingly, reduce carbon emissions.

Influence of recycling waste hardened mortar and ceramic rubbish on the properties of flowable fill material

Abstract Fly ash (FA) cement and water make up flowable fill material, which is also generally produced from waste and utilized in place of compacted granular fill as a cost-effective fill or backfill material. The capability to produce mixtures from various inexpensive, locally available by-products is one of the main benefits of flowable fill material. To considerably reduce costs, this study designed flowable fill mixtures utilizing cement, recycled fine aggregate (RFA; recycling waste hardened mortar and ceramic rubbish), FA, superplasticizers (SPs), and water for various uses. Initially, FA, Portland cement, fine natural aggregate, and water were combined to create a control mixture. Recycled aggregate (recycling waste hardened mortar and ceramic rubbish) was used instead of normal aggregate in various mix proportions in weights of 10, 20, 30, 40, and 50%. They performed well and conformed to the requirements of flowable fill material concerning flow consistency, unit weight, compressive strength, direct tensile strength, and thermal conductivity. Finally, when compared to ordinary concrete, flowable fill material can be produced with minimal mechanical criteria, such as a compressive strength of fewer than 5.71 MPa after 60 days and a unit weight between 1,993 and 1,961 kg/m3. Additionally, it was discovered that using more RFA to replace normal fine aggregate in flowable fill materials could result in a relative decrease in thermal conductivity.

A comprehensive investigation on the impacts of steel slag aggregate on characteristics of high-performance concrete incorporating industrial by-products

Steel slag (SS), an industrial by-product of the steel industry, has the potential to serve as a natural aggregate alternative in concrete production to not only mitigate the exploitation of natural resources but also minimize the environmental impact of its treatment and disposal. This study was designed to investigate comprehensively the impacts of using SS as a full replacement for coarse aggregate and of using fly ash (FA) and ground granulated blast-furnace slag (GGBFS) as partial replacements for Portland cement on the engineering properties (i.e., workability, fresh unit weight, porosity, compressive and flexural strengths, ultrasonic pulse velocity, and drying shrinkage), durability (i.e., water absorption, surface electrical resistivity, and rapid chloride ion penetration), and microstructure (i.e., scanning electron microscopy observation) of high-performance concrete (HPC). A comparative analysis of the economic and environmental benefits of SS concrete versus natural aggregate concrete was also performed. The test results revealed that SS, FA, and GGBFS all impacted the properties of HPC significantly. The HPC mixtures in which natural aggregate had been completely replaced with SS exhibited about 20.4–21.3% higher unit weight than the natural aggregate concrete. The HPC samples with added FA and GGBFS exhibited enhanced performance in terms of mechanical strength, durability, and microstructure. Moreover, total material cost, global warming potential (GWP), and ozone depletion potential (ODP) were all found to be significantly lower in the HPC samples produced using SS and either GGBFS or a combination of FA and GGBFS. As a result, after 210 days of normal curing, the 100% SS concrete containing 15% FA and 35% GGBFS as a Portland cement substitution (S100F15G35 specimen) exhibited compressive and flexural strength values of 110.3 and 11.1 MPa, which were approximately 9.0% higher than the corresponding values of the reference concrete. Also, the S100F15G35 specimen registered the respective ultrasonic pulse velocity, surface electrical resistivity, and rapid chloride ion penetration values of 5328 m/s, 113.3 kΩ.cm, and 203 Coulombs, indicating high-quality and durable concrete. Moreover, incorporating 15% FA and 35% GGBFS in SS concrete resulted in a reduction of 15.7% drying shrinkage and 24.4% total material cost, especially reduced environmental impacts with a significant reduction in GWP and ODP by 43.5% and 29.2%, respectively. These findings further demonstrate the potential of using SS in combination with FA and GGBFS to create high-quality HPC that is both more economical and significantly more sustainable than conventional HPC.

Underground storage tank blowout analysis: Stability prediction using an artificial neural network

Most geotechnical stability research is linked to “active” failures, in which soil instability occurs due to soil self-weight and external surcharge applications. In contrast, research on passive failure is not common, as it is predominately caused by external loads that act against the soil self-weight. An earlier active trapdoor stability investigation using the Terzaghi's three stability factor approach was shown to be a feasible method for evaluating cohesive-frictional soil stability. Therefore, this technical note aims to expand “active” trapdoor research to assess drained circular trapdoor passive stability (blowout condition) in cohesive-frictional soil under axisymmetric conditions. Using numerical finite element limit analysis (FELA) simulations, soil cohesion, surcharge, and soil unit weight effects are considered using three stability factors (Fc, Fs, and Fγ), which are all associated with the cover-depth ratio and soil internal friction angle. Both upper-bound (UB) and lower-bound (LB) results are presented in design charts and tables, and the large dataset is further studied using an artificial neural network (ANN) as a predictive model to produce accurate design equations. The proposed passive trapdoor problem under axisymmetric conditions is significant when considering soil blowout stability owing to faulty underground storage tanks or pipelines with high internal pressures.

Study on the destruction law of physical and shear properties of soil in mining disturbance

Underground mining activities can easily trigger surface subsidence and cause damage to surface soil. However, there is still a lack of studies on damaged soil, restricting ecological remediation in mining-induced subsidence regions to a certain degree. Focusing on the particular example of No. 4 Mine in Yili, Xinjiang, China, this study comprehensively combined field sampling, laboratory experiments, and data analysis to investigate the variation rules of basic physical properties and shear characteristics of soil samples. The latter had different subsidence degrees (0, 0–20, 20–40, and above 40 cm) and various depths (0– 10, 10–20, 20– 40, 40–60, and 60–80 cm). The experimental results show that: First, the natural density and dry unit weight of shallow soil in the serious-subsidence region were more significantly affected by mining-induced subsidence than the conditions in the deep layer, which also dropped with the increase in subsidence degree (with a mean drop rate of 7%). Second, serious subsidence could greatly counteract the positive effect of slight and moderate subsidence on the soil shear strength, with a drop rate of up to 30.7%. Third, compared with soil physical indices, mining-induced subsidence more easily affected shear strength indices. In particular, the soil samples taken from 0 to 10 cm depth in the slight subsidence area and 60–80 cm depth in the moderate subsidence area were most significantly affected by mining-induced subsidence, with PCA comprehensive scores of over 1.5. The present study can con-tribute to gaining in-depth knowledge of the damage characteristics of surface soil under mining-induced subsidence and provide a theoretical foundation for formulating reasonable coal mining strategies and ecological protection measures.

Reusing Dredged Material through Stabilization with So-Called Bio-Enzyme Products

Sediments are dredged from waterways to maintain maritime activities and prevent floods. Exorbitant amounts of money are budgeted for the removal of dredged material (DM) and its disposal in landfills. We investigated the potential for reuse of DM as a road construction material using so-called bio-enzyme products as stabilizing agents. To improve the mechanical properties of DM, such as compressive strength, compressibility, Atterberg limits and the California bearing ratio (CBR), mixtures of DM were tested with two different amounts of a commercially available bio-enzyme product, which yielded enzymatically stabilized dredged material (ESDM). Unconfined compressive strength (UCS), compaction and Atterberg limits were measured in accordance with ASTM specifications on all samples. Data show that the addition of bio-enzymes resulted in increases in UCS but did not affect the optimum moisture content (OMC), maximum dry unit weight or Atterberg limits of the DM. A comparative field study was carried out to evaluate the CBR of the CH subgrade before and after treatments with the bio-enzyme product and with lime as a traditional stabilizing agent. The results of the field study supported the laboratory findings. Based on these data and results from the literature, models predicting the effect of bio-enzyme treatments on the value of CBR and of UCS were developed statistically. These models also underlined the importance of the clay fraction and PI values for the improvement of the engineering properties of soil using bio-enzyme additives.

The role of bentonite in two-component grout: A comparative study

Two-component grout is the most used backfilling technology in shielded mechanised tunnelling. Bentonite is an important ingredient in the production of component A, since it plays a key role in the mortar stabilisation. Furthermore, recent studies have highlighted its involvement in the mechanical and elastic performance of the hardened grout after short curing times, while no information is available for long curing times. This study proposes an innovative test campaign, based on a comparison between a standard two-component grout mix design (reproduced with 5 different bentonites) and a special mix design, produced without using the bentonite. This interesting comparison highlights the important role of the bentonite and its activation time in properties related to fresh grout (component A) and hardened grout. Assessments of bleeding, viscosity, unit weight, gel time, surface compression strength (SCS), uniaxial compression strength (UCS) and tensile strength (T0) have permitted a deep quantitative analysis that, undoubtedly, highlights the importance of bentonite in this widespread backfilling grout technology.

A practical approach for soil unit weight estimation using artificial neural networks

The soil unit weight is a relevant geotechnical and geological parameter in interpreting field tests, estimating parameters, and developing designs. The most precise way to estimate the soil unit weight is through controlled laboratory tests, which require samples with undisturbed structures. However, such tests produce results specific to the extracted sample point and depth, making the abstraction difficult in large areas. Efforts in the literature rely on in situ penetration tests and mathematical equations to simplify estimating the parameter value for general scenarios. On the other hand, each sort of soil can have a characteristic behavior, reducing the precision of estimations and hindering the adoption of statistical-based models universally. We propose a practical approach supported by machine learning to predict the soil unit weight, which produces estimations with an R2 of 0.82. The methodology consists of three phases: (i) we perform a clustering analysis to understand if different soils have similarities that permit the generation of multiple models; (ii) we statistically examine soils parameters to identify relevant parameters and produce a regression model, and; (iii) we feed an ANN with in situ parameters to estimate the soil unit weight. We make publicly available a web application to estimate the soil unit weight.

Effect of nano-gypsum on mechanical properties cement admixed marginal silty soil

Even though the chemical stabilization is by far the most common ground improvement technique, very few studies have been conducted on the joint incorporation of two or more additives (cement-nanogypsum mix) to stabilise soft soil. This study investigates the effect on the mechanical properties of cement-stabilised silty soft soil (CSS) using nano-gypsum (NG). Unconfined compression strength (UCS) test trials were conducted to achieve soft soil conditions. The effect of NG and cement on soft soil was investigated by performing Atterberg limit, compaction, UCS, and Direct shear tests. The soil was treated with four percentages (10%, 15%, 20%, and 25%) of cement and with three percentages (1%, 1.5%, and 2%) of NG by its dry unit weight. The test results showed that the plasticity index of the soil was reduced significantly by the addition of stabilizers (Cement-NG mix) making the soil stiffer. The compaction tests suggested that optimum cement content was 20% for CSS and for cement-NG mix maximum strength was achieved at cement: NG proportion of 20:1. The unconfined compression strength (UCS) was increased by 9.11 times in comparison to untreated soft soil at cement: NG proportion of 20:1.5. The direct shear test (DST) suggested that there was an increase in cohesion by 4.44 times in comparison to the untreated sample at the soil–cement-NG combination of 78.5: 20: 1.5. However, the angle of internal friction remained almost unchanged. The development of cementitious substances was confirmed through XRD spectroscopy. Microstructural and chemical properties were observed using combined FESEM-EDAX analysis and Fourier transform infrared spectroscopy (FTIR). The multivariate linear regression (MLR) predictive model was developed for the unconfined compressive strength and failure strain as a function of various parameters considered in the study. The test results demonstrated that the combination of cement and NG can result in remarkable improvement in the geotechnical properties of soft soil. The use of NG may also reduce the demand for cement in deep cement mixing technique, which eventually reduces the carbon footprint and renders the ground improvement technique, ecologically beneficial.

Shrinkage and thermo-mechanical properties of concretes incorporated with different substitutions of natural aggregates by cold bonded calcined attapulgite lightweight aggregates

Calcined attapulgite (CAT), a fibrous calcined clay represents a promising option for advancement as a relatively new cementitious material with strong pozzolanic activity. This study investigates the impact and potential use of CAT in producing cold-bonded lightweight aggregates and their utilization in microsilica (MS) and fly ash (FA) blended concretes by analyzing the shrinkage and thermo-mechanical behavior. Initially, attapulgite rocks were processed including crushing, grinding and calcination to produce pozzolanic material. Following this, a dry powder mix of 80% calcined attapulgite (CAT) and 20% Portland cement (PC) was pelletized into calcined attapulgite lightweight aggregates (CATLWAs) using cold bonding with moisture and cured for 28 days. Subsequently, twelve concrete mixtures were formulated considering different substitutions of normal aggregate with CATLWAs and various proportions of PC, MS and FA. Mechanical properties such as compressive, splitting, and flexural strengths as well as elastic moduli and impact resistance were evaluated. Drying shrinkage, weight loss and thermal conductivity were assessed for all mixtures. Likewise, scanning electron microscopy was employed to analyze microstructural changes. Experimental results indicated that the incorporation of fine and coarse CATLWAs reduced the concrete unit weight by approximately 22% compared to the control mixture. However, there was a declining trend in mechanical properties, especially for impact resistance with increasing CATLWA content. However, the use of binary and ternary blends of cementitious materials improved overall mechanical behavior. Regardless of CATLWA content, the utilization of CATLWA enhanced thermal conductivity up to 46.9%. These findings hold significance for using CATLWAs in sustainable lightweight concrete production, thus advancing lightweight concrete technology and offering valuable insights into their advantages and constraints.

Carbon accounting per unit of food and unit of land in food production systems of Argentina

Based on the notion of Life Cycle Assessment (LCA), the carbon footprint (CF) is an extensively used concept that quantifies and informs carbon load per unit weight (e.g., kg C/ton food) in the food system. In line with LCA, the CF computes emissions at pre-farm, farm and post-farm stages throughout a given food chain. However, the CF contribution to C accounting may sound incomplete because gains of C by photosynthesis at the farm stage are set aside. The notion of carbon balance (CB), which computes both C emission and capture (e.g., in ton C/ha), may be relevant in food production systems based on the extensive use of land. Because of the high weight that farm processes have on entire food chains, in this investigation we focused the analysis on the farm stage. In order to assess the suitability of CF and CB in extensive food production systems, we analyzed results from CF and CB in 70 surveyed commercial farms distributed across three large climatic regions (subtropical and temperate) of Argentina. The CF and CB of four relevant farming activities (beef, maize, soybean and wheat production) were compared during the year 2019. The comparison yielded contrasting results and opened space for different interpretations: The notion of CF seems to be useful in intensive food-production systems that rely on inputs and activities that depend on a high consumption of fossil fuels. Conversely, CB appears to be useful in food-production systems associated with an extensive use of land and the gain of C through a large plant-photosynthesis platform.

Effects of High Temperature and Cooling Regimes on Properties of Marble Powder-Based Cementitious Composites

The demand for cement is increasing every day worldwide. To meet this demand, natural resources are rapidly being depleted. The excessive consumption of natural resources encourages researchers to conduct studies on the use of waste materials instead of cement. Marble waste is one of the major natural wastes abundantly generated worldwide. It has been evaluated that there is a gap in the literature regarding a study comparing the effects of different cooling regimes on cementitious composites with a marble powder (MP) replacement that has been exposed to high temperatures. In this study, waste marble powder (MP) was used as a replacement for cement at percentages of 5%, 10%, 15%, 20%, and 25% by mass. The water-to-binder ratio was kept constant at 0.5 for all mixture groups. Subsequently, the prepared cementitious composites were exposed to high temperatures (300 °C, 600 °C, and 800 °C) and subjected to air- and water-cooling regimes. Within the scope of this study, unit weight (Uw), ultrasonic pulse velocity (UPV), flexural strength (ffs), compressive strength (fcs), and mass loss tests were conducted. Additionally, a microstructure analysis was carried out using scanning electron microscopy (SEM) to examine the effect of MP replacement and the cooling regime. When examining the results of the samples tested in the laboratory, it was observed that the mortar with 5% MP replacement exhibited better mechanical properties compared with the others. In general, it can be said that the mechanical properties of samples cooled in air after exposure to high temperatures were better than those of samples cooled in water. As a result of this study, it was determined that MP replacement could positively contribute to the resistance of cementitious composites to high temperatures. Additionally, the use of a significant amount of waste MP can lead to savings in cement usage and significant reductions in CO2 emissions.

Enhancing Broccoli (Brassica oleracea var. italica) Growth, Yield and Water Productivity through Irrigation and Mulching Techniques in Local Climate

Introduction: Broccoli's efficient irrigation management is critical with changing climatic patterns and increasing water scarcity. The study aimed to assess the impacts of various irrigation methods and mulching techniques on broccoli cultivation.
 Methodology: A randomized complete block design with three replications was used, considering two factors: irrigation methods (drip and surface) and mulching materials (black polythene, white polythene, grass straw, and no mulching).
 Results: Drip irrigation, combined with black polythene mulching (I1MBP), consistently demonstrated its superiority that significantly improved multiple aspects of plant growth, yield and water productivity. In particular, I1MBP resulted in the highest plant heights at different growth stages, with the tallest plants at harvest (43.87 cm). However, surface irrigation with the same mulching (I2MBP) also showed higher plant heights but slightly shorter than drip irrigation. A similar trend was observed for the number of leaves per plant, with the I1MBP treatment having the most leaves. In curd development, the treatment (I1MBP) produced curds with larger diameters and lengths at harvest. In contrast, surface irrigation with the same mulching (I2MBP) also showed a larger curd size but, again, slightly lower than drip irrigation. In terms of curd initiation time, the I1MBP treatment had a longer duration, while the I1MN treatment had a shorter duration. Surface irrigation treatments followed a similar trend. With respect to yield, the I1MBP consistently had the highest unit weight of curd (423.14 g plant-1), yield per plot (25.39 Kg plot-1), and total yield (16.93 t ha-1), regardless of the mulching condition. However, surface irrigation with the same mulching (I2MBP) also showed higher yields (15.93 t ha-1) but slightly less than drip irrigation. On the other hand, the I1MBP demonstrated superior water use efficiencies (74.68 kg/ha-mm) and productivity (7.47 Kg m-3) compared to other treatments. Still, surface irrigation with the same mulching (I2MBP) also exhibited better water use efficiency (64.98 kg/ha-mm) and productivity (6.50 Kg m-3) than treatments with no mulch. Environmental factors, including temperature, humidity, wind speed, sunshine hours, and evaporation, were found to correlate with broccoli growth stages, emphasizing their influence on crop development.
 Conclusion: Finally, drip irrigation and black polythene mulching are pivotal for improved growth, yield, and water management, contributing to sustainable agriculture practices.

Effect of aluminosilicate precursors and curing regime on physico-mechanical durability and microstructural characteristics of coral geopolymers (Cor-Geo): Cleaner production for coral islands

This study investigated the mechanical, durability, microstructure, carbon footprint and cost characteristics of new-generation metakaolin-based geopolymer composites. Instead of GBFS, 25 % metakaolin was used, and 25 % and 50 % coral fine aggregate (CFA) was used instead of coral filler (FC). The produced coral geopolymers were cured at 30 °C (24 h) and 80 °C (8 h). The apparent porosities of coral geopolymers cured in the ambient cured range from 7.3 to 9.2 %, and those heat cured vary between 3.8 and 6.2 %. The immersion water absorption of the ambient cured coral geopolymers exceeded 5 %, while the water absorption of the heat-cured specimens was much lower than 5 %. The dry unit weights of coral geopolymer are between 2100–2200 kg/m3. In ambient cured coral geopolymers, compression strength up to 40 MPa was obtained after 24 h, while compression strength of almost 100 MPa was obtained after 8 h of heat curing. The ambient cured capillary water absorption of the mix with 50 % CFA was 3.5 kg/m2, while the capillary water absorption of the specimen without CFA and heat cured was less than 0.5 kg/m2. Exposed to 750 °C, the compression strength of all coral geopolymers was more than 10 MPa. The compression strength of the samples exposed to MgSO4 decreased by 10–60 %. The CO2 emissions of coral geopolymers range between 328 and 340 kgCO2/kg, and their costs between 411 and 442 USD/m3. As a result, it has been determined that geopolymer composites can be used for both prefabricated and construction sites in coral islands with coral aggregates.

AN INTEGRATED GEOTECHNICAL INVESTIGATION FOR STRUCTURAL FOUNDATION SUITABILITY ACROSS NIGER RIVER, NORTH CENTRAL NIGERIA

- The need to assess the suitability of foundation soil for oil and gas installations, such as pipeline, stations, and all other ancillary facilities, necessitated this study across the Niger River of north central Nigeria. A total of 17 boreholes and cone penetration tests were conducted. Samples were recovered from the boreholes and tested in the laboratory to obtain soil parameters. The investigation revealed that the subsurface is essentially composed of FINE SAND/SAND and CLAY. The FINE SAND is largely the superficial soil except in BH1 where CLAY is the superficial soil. The FINE SAND is loose at the top becoming medium dense and clayey at the base as it grades into CLAY. It has a greyish colour, with moisture content between 6% and 29% and bulk unit weight between 15.17 kN/m3 and 21.76 kN/m3 . The CLAY underlies the FINE/SAND and SAND. It is generally greyish in colour, with moisture content between 12% and 29% and bulk unit weight between 15.17 kN/m3 and 21.30 kN/m3 and an average strength of 156 kN/m2 except where it is the surficial soil and soft (strength < 25 kN/m2 ). Oversize materials were not encountered during the investigation and as such shall not pose any risk to horizontal directional drilling operation. However, on the Island, within the FINE SAND, bed of gravel occurs in BH8 and BH9. In terms of plasticity, due to saturation, the soils are not expected to swell. Nevertheless, it is advisable to add polymers to the drilling mud to prevent transfer of water from the drilling fluid into the soil as a precaution for clayey soils at the entry and exit points and on the Island. Most of the soil contains fines less than 30% and therefore, specific measures may be employed to improve borehole stability during drilling and installation.

Study Komparasi Penambahan Palm Oil Ash Dengan Bantuan Semen Berdasarkan Nilai California Bearing Ratio

High water content, water saturation, and low carrying capacity are characteristics of clay soils. The road body may have an uneven surface. On the other hand, in the dry season it will harden and have a high carrying capacity so that a lot of dust is scattered on the road and blocks the driver's view. As a result, the neighborhood can experience traffic jams and accidents. Check the CBR and PI values to see if there is an increase in clay after stabilization using a mixture of Palm Oil Fuel Ash and cement with variations (0% POFA + 2% Cement), (3% POFA + 2% Cement), (5% POFA + 2% Cement), and (7% POFA + 2% Cement). Test method Sieve Analysis, Atterberg Limit, Specific Gravity, Moisture Content, Compaction and CBR. Cement and palm oil bunch ash produced a CBR value of 7.4% compared to a natural soil CBR value of 1.59%. The CBR value of the soil will increase, the dry unit weight value will decrease, and the plasticity value will decrease with the higher proportion of Oil Palm Bunch Ash and cement

Construction of Temporary Landfill Shield by Utilizing MICP Stabilized Water Treatment Plant Sludge Waste

The addition of Bacillus Subtilis bacteria to the mud soil at IPAM (Integrated Wastewater Treatment Plant) Perumda Tirta Manuntung Km.8 in Balikpapan City aimed to enhance its suitability as a temporary cover layer in places like landfills. Initial mud testing revealed key characteristics: Chemical Characteristics: The mud's specific chemical composition was identified, providing a foundation for a deeper understanding of its properties. Physical Characteristics: The mud falls into the fine-grained soil category, with 63% of particles passing through a No. 200 sieve. Moisture content is high at 42.54%, primarily composed of silt (39.8%) and clay (25%). Mechanical Characteristics: Standard proctor tests yielded a maximum dry unit weight of 1.099 gr/cc and an optimum water content of 33.65%. Initial soil permeability met temporary landfill cover criteria, with a permeability value of 5.04×10-4 cm/s. Further research demonstrated that by introducing Bacillus Subtilis bacteria at varying concentrations and incubation periods, mud permeability could be altered. The highest permeability, 4.27×10-4 cm/s, was achieved with an 8% bacteria concentration and a 7-day incubation period, while the lowest permeability, 1.19×10-5 cm/s, resulted from an 8% bacteria concentration and a 28-day incubation period. These findings suggest that Bacillus Subtilis addition can modify mud permeability, making it more suitable as a temporary landfill cover. This presents a potential solution for more effective IPAM management.