Proportion Of Aggregates Research Articles

Effects of long-term super absorbent polymer and organic manure on soil structure and organic carbon distribution in different soil layers

Super absorbent polymer (SAP) and organic manure (OM) may improve soil structure and change soil organic carbon (SOC) composition and agroecosystem functioning. However, the understanding of the effects of SAP and OM on SOC composition, specifically in deeper soil layers, is still not clear. The objectives of this study were to examine the effects of long-term application of SAP and OM (8 years) on changes in SOC and soil structure down to a soil depth of 100 cm. Therefore, in order to investigate the stability of soil structure and the distribution of organic carbon at different soil depths (0-10 cm, 10-20 cm,…, 90-100 cm) under long-term application of SAP, OM, and a control treatment, soil structure and soil organic carbon content were analyzed in mixed soil samples and undisturbed soil samples. The results indicated that with depth, the proportion of large aggregates (0.5-2.0 mm) decreased gradually, while the proportion of small aggregates (<0.25 mm) increased gradually. Compared with the control, SAP treatment was conducive to the increment of>0.5 mm soil aggregates in the 0-30 cm and 40-60 cm soil layers (P < 0.05) and 0.25-0.5 mm in the 0-50 cm soil layer (P < 0.05), and while the OM treatment had the same effect in the 0-30 cm soil layer (P < 0.05). The total organic carbon content (TOC) and labile organic carbon content (LOC) of bulk soil increased (0-20 cm) initially with depth, and then decreased (20-70 cm) approximately. In the 0-50 cm soil layer, the TOC and LOC under SAP treatment were higher than those under OM treatment. The SAP treatment was more beneficial to the increase of the TOC and LOC of 0.5-2.0 mm and 0.25-0.5 mm aggregates in the 10-40 cm soil layer compared with the control and OM treatment (P < 0.05). The SAP treatment was also more beneficial in increasing the contribution rate of organic carbon (CROC) in> 0.5 mm aggregates in 0-40 cm soil depth, while the OM treatment was more beneficial in increasing the CROC of > 0.5 mm aggregates in 0-30 cm soil depth. The SAP treatment improved the stability of the soil structure in 0-30 cm and 40-60 cm depths, and the OM treatment had the same effect in the 0-30 cm depth. Compared with the control and OM treatments, SAP treatment has shown to be the most beneficial in improving soil structure and increasing organic carbon content.

A New Approach for Designing Fluid Concrete with Low Cement Content: Optimization of Packing Density of Aggregates.

The current study aims at proposing a novel and simple method for designing fluid concrete such as self-compacting concrete (SCC) with a low cementitious binder content to reduce the carbon footprint. Different testing methods regarding the packing density of aggregate mixtures are performed and compared. The W/C was determined according to the target compression strength. Slump flow spread is carried out to determine the most appropriate superplasticizer (SP) dosage and aggregate volume fractions and proportions in concrete mixtures. Furthermore, hardened performance, including compression strength and drying shrinkage of the fluid concrete, are characterized. Finally, a mix design process of fluid concrete with low cement content was proposed based on the preferred fresh and hardened properties of the concrete mixtures.

Investigations on mechanical and thermal properties of concrete with different proportions of insulation aggregates

AbstractInvestigation of mechanical properties and thermal behavior of expanded polystyrene concrete (EPS) and exfoliated vermiculite (EV) concrete has been accomplished in this research. It includes how EPS concrete is prepared by substituting the coarse aggregate with 0, 10, 15, and 20% with EPS aggregates. Similarly, EV concrete is prepared by replacing the fine aggregates with 0, 15, 45, and 60% with EV aggregates. The influence of EPS and EV proportion on mechanical and thermal properties was detected. Thermal properties were studied with an adiabatic box technique. Clear improvement in thermal behavior was observed in comparison with normal concrete and reduction in compressive strength was observed for an appreciable increase in the amount of EPS and EV. Also, the properties like split tensile strength, load–deflection curves, and durability properties of the EPS and EV concretes were experimented.

Soil aggregate stability increased with a self-regenerating legume cover crop in low-nitrogen, no-till agroecosystems of Saskatchewan, Canada

Black medic (Medicago lupulina L.) is a self-regenerating cover crop which was tested for its ability to improve soil physical properties. Soil aggregate stability was assessed in plots that included a black medic cover crop in a no-till grain rotation, which was fertilized with two levels of nitrogen (N), for 15 yr. In the wheat phase of the rotation, the medic cover crop increased mean weight diameter by 21% in the reduced N fertilizer treatment but not in the recommended N treatment. Generally, the addition of medic reduced the proportion of small aggregates and increased the proportion of large aggregates. This pattern was stronger in reduced N compared with recommended N fertilizer levels. This study provided evidence for medic to increase aggregate stability under low external N input grain production.

Rank Equity Index: Measuring Parity in the Advancement of Underrepresented Populations in Academic Medicine.

As educators, researchers, clinicians, and administrators, faculty serve pivotal roles in academic medical centers (AMCs). Thus, the quality of faculty members' experiences is inseparable from an AMC's success. In seeking new methods to assess equity in advancement in academic medicine, the authors developed the Rank Equity Index (REI)-adapted from the Executive Parity Index, a scale previously implemented within the business sector-to examine national data on gender and racial/ethnic equity across faculty ranks. The REI was employed on self-reported demographic data, collected by the Association of American Medical Colleges, from U.S. medical school faculty in 2017, to make pairwise rank comparisons of the professoriate by demographic characteristics and department. Overall results indicated that women did not attain parity at any pairwise rank comparison, while men were above parity at all ranks. Similar results were observed across all departments surveyed: women in the basic sciences had REIs closest to parity, women in pediatrics had the highest representation but had REIs that were further from parity than REIs in the basic sciences, and women in surgery demonstrated the lowest REIs. Nationally, REIs were below 1.00 for all racial/ethnic group rank comparisons except for White and, in one case, multiple-race non-Hispanic/Latinx. Across all analyzed departments, Black/African American, Asian, Hispanic/Latinx, and multiple-race Hispanic/Latinx faculty had REIs below parity at all ranks except in 2 cases. In a comparison of 2017 and 2007 data, REIs across both race/ethnicity and gender were lower in 2007 for nearly all groups. REI analyses can highlight inequities in faculty rank that may be masked when using aggregate faculty proportions, which do not account for rank. The REI provides AMCs with a new tool to better analyze institutional data to inform efforts to increase parity across all faculty ranks.

Quality Control of Production Lightweight Ferrocement Plate Using Sustainable Materials

This research is concerned with a new type of ferrocement characterized by its lower density and enhanced thermal insulation. Lightweight ferrocement plates have many advantages, low weight, low cost, thermal insulation, environmental conservation. This work contain two group experimental : first different of layer ferrocement, second different of ratio aggregate to cement. The experiments were made to determined the optimum proportion of cement and lightweight aggregate (recycle thermestone ). A low W/C ratio of 0.4 was used with super plasticizer conforming to ASTM 494 Type G. The compressive strength of the mortar mixes is 20-25 MPa. The work also involved the determination of thermal properties .Thermal conductivity value of this ferrocement plate is between (0.6-0.45)W/m.K.

Field Application of Pervious Concerte for Recharge of Groundwater

In the present study, an attempt has been made to investigate strength and permeability of pervious concrete made with different combinations of aggregate sizes (20mm,12.5mm and 10mm) and different mix proportions using flyash and super platiciciser). The main objective of this investigation is to apply the pervious concrete through a footpath to improve groundwater recharge by finding out the best combination of grading of aggregates and also the mix proportion with fly ash for obtaining optimal permeability and strength. The effect of partial replacement of cement with fly ash and super plasticizer on the compressive strength and the water permeability of pervious concrete are investigated. The analysis of the test results indicated that the proposed combination of materials have increased the compressive strength significantly and also, the water permeability. Even though, the individual performances (maximum strength and maximum permeability) of some of the combinations obtained are good, but it is expected in the study to have reasonable values for both to use pervious concrete in the field. Hence, in this study, it is considered the intersection point on the strength versus permeability graph as the best combination. So, the combination with 40% of 20mm, 30% of 12.5 mm and 10mm and 10%flyash with 90% opc (53 grade) without super plasticizer considered as the best which gives 24 MPa and 15.6 mm/s permeability.. A footpath of size 1.2 m (width) x 0.25 m (thickness) x 19 m (length) is selected for laying pervious concrete in the form of number of panels. A constant discharge is applied on to the footpath in lateral direction and it is found that the absorption capacity of the laid mix in the field is 115.52 litres/ m length.

Evaluation of Ballistic Resistance Performance by Thickness and Proportion of Magnetic Aggregate of Concrete

Evaluation of Ballistic Resistance Performance by Thickness and Proportion of Magnetic Aggregate of Concrete

Particle distribution around the damage area of asphalt mixture based on digital image correlation

Asphalt mixture is a kind of granular material, which consists of aggregates with different particle sizes. Extracting the particle distribution around the failure location of asphalt mixture is important for revealing the failure mechanism. In this paper, the digital image correlation (DIC) method is used to obtain the full-field strain of asphalt mixture, and then the high strain zone of asphalt mortar is extracted by digital image processing technology. For getting the aggregate distribution around the failure position, aggregate extraction method is proposed based on the image dilation algorithm. For AC-16, SMA-16 and OGFC-16 asphalt mixtures, under different temperature and loading speed conditions, according to the analysis of the aggregates distribution around the high strain area, it can be seen that the proportion of the main skeleton aggregates and the disruption aggregates around the high strain area is constantly changing with the loading process. It shows that the proportion of the main skeleton aggregates around the high strain area is decreasing, while the proportion of the disruption aggregates is increasing. This phenomenon shows that the damage evolution of asphalt mixture is expanding from the surrounding area of main skeleton aggregates to that of disruption aggregates.

Comparative study of lignin stabilizing mechanisms in soil aggregates at virgin mixed broadleaf-pine forest and secondary broadleaf forest at Changbai Mountain Nature Reserve, Northeast China

The variation of soil organic carbon (SOC) stability is independent of the amount of SOC in the soil. For predicting the conservation of soil carbon in different forest ecosystems, it is crucial to investigate the mechanisms of plant derived residues allocation and stabilization in soil aggregates in different forest ecosystems. The role of aggregate protection in SOC sequestration (using lignin as a biochemical indicator) requires understanding of the interaction of many factors. We studied aggregate proportion, SOC amount and lignin phenol contents in the soil fractions from 0–5, 5–10 and 10–20 cm layers in a virgin mixed broadleaf-Korean pine (BK) and secondary broadleaf Betula-Populus (BP) stands at Changbai Mountain Nature Reserve, Northeastern China. Macroaggregates had higher lignin contents compared to the bulk soil in both BK and BP. The SOC and lignin contents in bulk soil and aggregates obviously declined with soil deepening in the two stands. BK exhibited more protected lignin in aggregates compared to the same particles from BP. The results suggested that the aggregates have limited capability to sequestrate more carbon, which causes carbon loss in the soil particles with soil depth increment in the secondary broadleaf forest. Stable lignin sequestration was achieved via effective aggregate protection in BK, while lignin occlusion was mainly regulated by the importation of plant residues into the topsoil of BP.

The effect of exposed aggregate concrete gradation on the texture characteristics and durability

To ensure a lower tire/road noise level and proper friction, exposed aggregate concrete (EAC) is widely used for the construction of major highways in Europe. Even though EAC is commonly used, the number of publications about the effect of the EAC composition on the texture characteristics and durability is lacking. Moreover, there are no publications about EAC mixtures for pedestrian sidewalks. The objective of this article is to develop a mixture gradation that will lead to better pavement surface characteristics and durability of EAC used for the wearing layer of highways and pedestrian sidewalks. Variations in the maximum coarse aggregate size and proportions were used to develop EAC mixtures. The experimental research results showed that increasing the amount of coarse aggregates improves the skid resistance, resistance to polishing, exposed aggregate peak number, and compressive strength but impairs the mean profile depth (MPD) and mean texture depth (MTD). Based on the evaluation of the experimental data collected in this study, all EAC mixtures with a maximum aggregate size of 8 mm (EAC 8) achieved higher compressive strength values than EAC mixtures with a maximum aggregate size of 5 mm (EAC 5). However, EAC 8 and EAC 5 showed similar values of flexural strength, splitting strength, skid resistance and resistance to polishing. The analytic hierarchy process (AHP) was developed and applied to prioritize all tested EAC alternatives considering the most important criteria. The EAC 5 mixture with 80% coarse aggregates fr. 2–5 mm (EAC 5_3) was selected as the most rational alternative for the wearing layer of pedestrian sidewalks, while the EAC mixture contained 70% coarse aggregate fr. 5–8 mm (EAC 8_1) was selected for the wearing layer of highways.

Soil aggregate size distribution and total organic carbon in intra-aggregate fractions as affected by addition of biochar and organic amendments

&lt;p&gt;A two-year field trial on maize (&lt;em&gt;Zea mays&lt;/em&gt; L.) production was established to determine the influence of biochar, maize straw, and poultry manure on soil aggregate stability, aggregate size distribution, total organic carbon (TOC), and soil microbial biomass carbon (MBC). Seven treatments with four replications, namely CK, control; S, 12.5 Mg ha-1 straw; B1, 12.5 Mg ha-1 biochar; B2, 25 Mg ha-1 biochar; SB1, straw + 12.5 Mg ha-1 biochar; SB2, straw + 25 Mg ha-1 biochar; and M, 25 Mg ha-1 manure were tested at four soil depths (0–10, 10–20, 20–30, and 30–40 cm). Aggregates were grouped into large macro-aggregates (5–2 mm), small macro-aggregates (2–0.25 mm), micro-aggregates (0.25–0.053 mm) and silt + clay &lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;(&amp;lt;0.053 mm). Biochar, straw,&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt; and manure applications all had significant effects (&lt;span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;&lt;em&gt;p &lt;/em&gt;&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;&amp;lt; 0.05) on aggregate stability, with B&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;2 &lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;at&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt; 20 cm soil depth showing the greatest increase (62.1%). SB&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;1 &lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;of small macro-aggregate fraction&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt; showed the highest aggregate proportion (50.59% ± 10.48) at the 20–30 cm soil depth. The highest TOC was observed in SB&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;2 &lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;(40.9 g kg&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;-1&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;) of large macro-aggregate at 10–20 cm soil depth. Treatment effects on soil MBC was high, with B&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;1 &lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;showing the greatest value (600.0 µg g&lt;span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;-1&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt;) at the 20–30&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt; cm soil depth. Our results showed that application of biochar, straw, and manure to soil increased&lt;span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"&gt; aggregate stability, TOC as well as MBC.&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

Diagnosis of Pathological Manifestations and Characterization of the Mortar Coating from the Facades of Historical Buildings in Porto Alegre — Brazil: A Case Study of Château and Observatório Astronômico

ABSTRACT This article presents the diagnosis of pathological manifestations on the mortar coating from the facades of two historical buildings of scientific and social importance in Porto Alegre, Brazil. Documental investigation, visual survey, percussion and thermography tests, mapping of damages, and characterization of the coatings were performed. Coatings were characterized by determining the binder:aggregate proportion and the aggregate particle size distribution; X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and qualitative test of soluble salts were performed. The damage maps present the extension of anomalies, like detachments and areas with moisture, which were located with support of thermography results. Mortar samples extracted from the buildings indicated binder:aggregate proportions, in dry mass, ranging from 1:1 to 1:2.7. In the binder, it was verified mainly the existence of calcite and quartz through XRD; with XRF, magnesium oxide was additionally verified and calcite was also found with TGA. Chlorides and sulfates were identified by XRF and test of soluble salts. The fineness module and the particle size distribution of siliceous aggregates from different samples were similar.

Physicochemical Characterization of Historical Coating Mortars – Case Studies in South Brazil

ABSTRACT The intervention process in historical buildings involves the application of a scientific methodology for the materials characterization. In Porto Alegre — RS, Brazil, several buildings with patrimonial value from the nineteenth and early twentieth centuries were preserved. This study presents the physicochemical analysis of mortar coating samples obtained from two buildings, the commercial and residential building “Frasca House” (1911) and the Metropolitan Curia of Porto Alegre (1888). The visual investigation and aspects of the color and morphology of the samples were determined with a stereoscopic microscope. Chemical analyses provided information on the binder:aggregate proportion and qualitative soluble salts, correlated with deterioration caused by efflorescence. Microstructural analysis allowed to determine the nature of the binders, aggregates and fine particulates. It is expected to contribute, in restoration interventions, to the choice and quantity of materials compatible with the original evaluated here, preserving it and, thus, extending the service life of the building.

Effect of Cement Content on Compressive and Bonding Strength with Steel Bar Reinforcement

Concrete is the most important building material due to the availability of its constituent materials and its easy manufacturing; it is commonly reinforced with a steel bar to resist the tensile stresses. The present research discusses the effect of cement content on the bonding strength with the steel bar reinforcement as well as the concrete strength while fixing the fine/coarse aggregate proportion, the slump and the water/cement ratio. Two series have been produced by using different types of steel bars (smooth and deformed) with a different cement content of (250, 300, 350, 400 and 450 kg/m3). These two parameters were used to study the effect of the cement content and the mechanical interlocking on the bonding strength between concrete and steel bars. The results of this study showed that the compressive strength increases with the increasing of cement content up to 400 kg/m3, and then there is no significant improvement in compressive strength. However, the bonding strength with the steel bar increases even at 450 kg/m3. For any cement content, the deformed bars exhibited a better bonding strength of several times than the smooth bars.

Analysis of AC-WC Design Material Using Reclaimed Asphalt Pavement

The recycling technique using materials produced by Cold Milling Machine is a potential alternative to be applied to road maintenance in Indonesia. This study aims to investigate the properties of Reclaimed Asphalt Pavement (RAP) used as Asphalt Concrete Wearing Course (AC-WC) so that the proportion of additional fresh aggregate can be determined. This laboratory-scale study uses the material of RAP from Semarang Section A toll road sections and penetrated asphalt of 60/70. The extraction analysis obtained asphalt content is between 3.50% - 4.36%, with abrasion of 29.04%. RAP cannot be used directly but there is a need to add fresh aggregate so that the mixture meets the specifications. The proportion of the mixture is 30% of RAP, 18% of the fresh aggregate, 50% of rock ash, and 2% of Cement. The analysis shows that the mixture with optimum asphalt content (5.7%) obtained 1188 kg of stability, 4.02% of VIM, 15.81% of VMA, 74.54% of VFWA, and 3.57 mm of flow. These values indicate that the mixture meets the revised version of the Technical Specifications of Bina Marga 2010. Therefore, it can be said that this mixture has high durability, good density, and is resistant to the possibility of bleeding.

Evaluation of Air Void and Cracking Characters of Cement-Stabilized Crushed Stone through X-ray Computed Tomography

This paper presents a method of quantifying the air-void distribution and cracking characters through X-ray computed tomography. Five mixtures are analyzed for air-void distribution, and two of them are tested for cracking development under compression. Results indicate that the meso-level air void in the five mixtures obviously differ, and the cracking-development rules are correlated on with the mixture gradation and air-void distribution. Good correlation is observed between the air-void frequency and the fractal dimension of gradation. The air-void rate on the upper part is larger than that on the bottom. Meanwhile, considering the effect of the end restraint, the cracking increment on the middle part are obviously than the upper and bottom part. The cracking in the cement-stabilized crushed stone is circular when the fine aggregate proportion is high (45%).

Effects of remelting and refining on the microstructure and properties of particle reinforced magnesium-lithium matrix composites

Particle reinforced magnesium-lithium matrix composite ingot was remelted and refined using a special 100Kg level vacuum induction melting system. The evolution of microstructure, mechanical properties and homogeneity of ingot before and after remelting and refining was described and analyzed based on quantitative characterization. The refining mechanism was also explored. The results show that the secondary mechanical stir effect in the remelting process can purify the melt and reduce casting defects, significantly improve the distribution homogeneity and effectively reduce the aggregation of reinforcement particles. After the remelting and refining of YAl2p/LA143 composite ingot, the homogeneity factor ζPD of reinforcement distribution increases by 22.8%, the area proportion of particle blocky aggregates decreases by 91.4%. The obvious atomic thermal diffusion effect between reinforcement phase and matrix phase was observed during the remelting and refining process. The element distribution of interface zone between reinforcement phase and matrix alloy phase shows a gentle curve transition after remelting and refining, which forms an excellent transition interface. Under the effects of secondary mechanical stir and atomic heat diffusion, the mechanical properties of YAl2p/LA143 composite remelting ingot are effectively improved, and the tensile strength, yield strength and elongation increase by 11.3%, 10.2% and 400%, respectively.

Closing the (incarceration) gap: assessing the socio-economic and clinical indicators of indigenous males by lifetime incarceration status

BackgroundApproximately 1 in 5 to 1 in 6 Indigenous Australian males are currently imprisoned or have previously been imprisoned. Recent work has also pointed to a widening socio-economic gap within the Indigenous population. Given the myriad social, wellbeing and environmental risk factors associated with justice-involvement, it is conceivable that incarceration may contribute to the increasing disparities found within the Indigenous population. This study aimed to explore the presence and extent of an ‘incarceration gap’ within the Indigenous population and to uncover which social factors characterise the disparity.MethodsThe study utilised data from the 2014–5 National Aboriginal and Torres Strait Islander Social Survey (NATSISS). A number of socio-economic, environmental and clinical factors were compared by life-time incarceration status. Chi-square tests were used to examine the association between incarceration status and each of the comparison variables.ResultsDisparities were observed within the Indigenous Australian population across a number of important health and socio-economic markers by incarceration status - the most pronounced being for educational obtainment – year 10 completion (Never incarcerated 73%, Ever incarcerated 50%), labour force participation (Never incarcerated 56%, Ever incarcerated 26%) and drug/alcohol problems (Never incarcerated 7%, Ever incarcerated 29%). Never-incarcerated Indigenous males yielded aggregate proportions across numerous variables that approximated or matched general Australian population estimates.ConclusionsThere appears to be evidence for a substantial ‘incarceration gap’ within the Indigenous Australian population.

Utilization of kimberlite tailings as aggregates in concrete - strength and selected durability properties

AbstractThe feasibility of using kimberlite tailings as aggregates in concrete was assessed. Compressive strength and selected durability tests were carried out on concretes made using various replacement levels (0, 40, 60 and 100%) fine and/or coarse blended crushed andesite and kimberlite tailings as aggregates. A w/b ratio of 0.50 and a CEM I 52.5R were used. The results show that the kimberlite tailings as aggregates have a relatively high water demand which was manifested as a reduction in workability of the fresh concretes with kimberlite tailings as a proportion of either fine and/or coarse aggregates. The results also showed that the use of the kimberlite tailings as a proportion of either fine or coarse aggregates in concrete resulted in a decrease in both compressive strength and durability properties viz water sorptivity and oxygen permeability. This was partly attributed to the low workability of the concretes which is known to limit the degree of compaction of fresh concrete. It is envisaged that careful concrete mix proportioning including the use of admixtures and pre-wetting of the aggregates can be used to offset the negative effects of high water demand of the kimberlite aggregates.