Experimental Assessment of Strength Parameters of River Sand for Sandcrete Block Production

Sandcrete block is a vital building material used in the construction of building structures. The sandcrete blocks are produced by different manufacturers using river sand obtained from different locations as aggregate material without recourse to the minimum quality standard for the blocks produced. The study assessed the strength parameters of river sand used as an aggregate material in block production to determine its quality and suitability in relation to the strength of block produced. Three (3) block manufacturing sites in Nigeria were visited and 27 (twenty-seven) blocks of size 450 mm x 225 mm x 225 mm were selected randomly from the sites. The properties of the river sand was analyzed through sieve analyses, bulk density, silt content and water absorption while the compressive strength of the blocks was also tested. The result of sieve analysis of the river sand used in block production for this study all satisfied the particle size requirements of BS EN 933-1:1997 for general construction work including block production. The result of the study also shows that blocks produced with the river sand after 28days have an average compressive strength of 1.23 N/mm2 (SW), 1.54 N/mm2 (SE) and 1.95N/mm2 (NE). The study, therefore, concluded and recommended that regulatory and professional bodies in partnership with relevant associations should organize seminars for producers of sandcrete blocks on the best practices involved in producing quality sandcrete blocks.

A comparative study of the quality of sandcrete cement blocks and quarry dust cement blocks

With the increase of construction activities in Ghana, there is an increasing demand in building materials leading to the shortage of the conventional materials. The informal sector is gradually seeing the introduction of quarry dust as a substitute of sand in block production. This paper focuses on a comparative analysis of the quality of sandcrete blocks and quarry dust cement blocks. Block samples were gathered from various suppliers around the Prampram and Dawhenya areas and through various laboratory tests were tested for their dimension tolerance, water absorption and compressive strengths. Aggregate samples were also taken from suppliers for sieve analyses. The study revealed that the quarry dust cement blocks contained relatively higher percentages of coarse grade particles compared to the sandcrete blocks. The total average water absorption of sandcrete blocks was found to be 3.90% while quarry dust showed an improved value of 3.28%. Sandcrete blocks were averagely found to be of a higher compressive strength of 4.31N/mm2, with quarry dust at 3.0N/mm2. The study suggested the likelihood of a lesser use of cement in the production of quarry dust cement blocks due to the similarities in colour between the quarry dust and cement, hence, negatively affecting its compressive strength.

Creep of calcareous sand in Tunisia: effect of particle breakage at low stress level

Aims/hypothesis One of the critical mechanisms determining creep in granular materials is the breakage of soil particles. This study aims at evaluating the time-dependent creep deformation of calcareous sand at low effective stress conditions. Methods K0 creep tests were performed for both calcareous and silica sands at low stresses of 65 and 120 kPa, and the results of creep tests were compared with the results of constant rate of strain (CRS) tests at high stress levels up to 12 MPa. For a quantitative evaluation of the effect of the particle breakage on the creep deformation of calcareous sand, the relative breakage ($$B_{r}$$ B r ) was determined based on the results of sieve analyses. Results The results demonstrate that Tunisia calcareous sand experiences significant particle breakage during creep and the consequent creep deformation at low stress level. The determined $$B_{r}$$ B r after creep at low stress level is comparable with that after the CRS test at high stress level. Conclusions High potential of particle breakage inherited by characteristic minerology of the calcareous Tunisia sand significantly influences the creep deformation at low stress level.

Granulometria osadów dennych kanału Przekop Wisły

The Przekop Wisły (or the Vistula Cross-cut) is a canal created 120 years ago in the Vistula River mouth to prevent floods. In 2013/2014, 82 samples of canal sediments were collected in the course of three sessions, which were next subjected to macroscopic descriptions and sieve analyses including calculation of granulation indices expressed in the phi scale. Characteristics of granulation are presented in relation to forms of bottom relief as well as varied transport and storage conditions of individual sessions. Sediments in the canal are relatively even-sized, with coarse and/or medium-grained sands, quite well-sorted, with moderately negative skewness and a leptokurtic distribution. It was demonstrated that deposition of sediments in the canal is progressing, especially in its estuarial section, which impacts significantly on its patency. Hence, it is necessary to monitor sediments in the canal in order to establish its condition and identify trends related to risks and flood prevention. The Przekop Wisły canal constitutes a natural area of a straight channel river, and studies of its sediments may be considered an important model of fluvial processes.

Assessment of the Possibility of Using Reclaimed Materials for Making Cores by the Blowing Method

The cumulative results of investigations of the possibility of using the reclaimed materials after the mechanical, thermal or mechanical-thermal reclamation for making cores by means of the blowing method in the alkaline CO2 technology, are presented in the paper. Three kinds of spent sands: with furfuryl resin, bentonite and alkaline phenolic resin, obtained from the foundry, were subjected to three kinds of reclamation: mechanical, thermal and combined mechanical-thermal, applying for this aim adequate experimental devices. The obtained reclaims were assessed with regard to the degree of the matrix liberation from the determined binding material. Reclaims of moulding sands with binders of the form of resin were assessed with regard to ignition loss values and pH reaction, while reclaims of moulding sands with bentonite with regard to the residual clay content and pH value. In all cases the results of the performed sieve analyses were estimated and the average characteristic diameter dl was determined. The reclaimed matrix was applied as a full substitute of the fresh high-silica sand in typical procedures of preparing core sands used for making shaped samples for bending strength investigations, Rgu.

A Study on the Characteristic and Properties of Riverbank Soil Samples as RBF Natural Materials from Sungai Perak, Kota Lama Kiri, Kuala Kangsar, Perak Darul Ridzuan, Malaysia

For a developing country such as Malaysia, riverbank/bed filtration (RBF) technology is still new and only few efforts have been made to understand the RBF mechanism and processes. Soil characteristics play important roles in determining the water quality and the ability of water to be abstracted from the wells during RBF process. A research has been carried out to identify the characteristic of riverbank soil at different layers in the pumping well (PW) borehole at Kota Lama Kiri, Kuala Kangsar, Perak, Malaysia. Soil samples were collected during the development of PW for RBF application. The maximum depth of PW was 8.50 metre. The soil samples were transported to Geotechnical Engineering Laboratory, School of Civil Engineering, Universiti Sains Malaysia and the properties were determined by a series of laboratory test. Soil particle size distribution (PSD) and hydraulic conductivity were obtained from sieve analyses and constant head test with reference to BS 1377: Part 1-9;2:1990. Laboratory results show that the value of Cu(coefficient of uniformity) for the soil samples within the borehole of PW was found to be within the range of 2.00 to 10.00 while the value of Cc(coefficient of gradation) lies in the ranges of 0.06-1.19. The One Way Analyses of Variance test was performed using Minitab statistical packages and the results indicate that the p-value was 0.996, where there was no significance difference between the mean sizes of soil samples within the PW. The hydraulic conductivity, k for PW ranges between 0.10-0.91 cm/s. Soil samples from depth 6.00-7.00 metres has the highest hydraulic conductivity, which is 0.91 cm/s. The overall well production from the pumping test was found 112.10 m3/hr.

Breakthrough Virus Neutralization Resistance as a Correlate of Protection in a Nonhuman Primate Heterologous Simian Immunodeficiency Virus Vaccine Challenge Study

ABSTRACTComprehensive assessments of immune correlates of protection in human immunodeficiency virus (HIV) vaccine trials are essential to vaccine design. Neutralization sieve analysis compares the neutralization sensitivity of the breakthrough transmitted/founder (TF) viruses from vaccinated and control animals to infer the molecular mechanisms of vaccine protection. Here, we report a robust neutralization sieve effect in a nonhuman primate simian immunodeficiency virus (SIV) vaccine trial (DNA prime/recombinant adenovirus type 5 [rAd5] boost) (VRC-10-332) that demonstrated substantial protective efficacy and revealed a genetic signature of neutralization resistance in the C1 region ofenv. We found significant enrichment for neutralization resistance in the vaccine compared to control breakthrough TF viruses when tested with plasma from vaccinated study animals, plasma from chronically SIV-infected animals, and a panel of SIV-specific monoclonal antibodies targeting six discrete Env epitopes (P< 0.008 for all comparisons). Neutralization resistance was significantly associated with the previously identified genetic signature of resistance (P< 0.0001), and together, the results identify virus neutralization as a correlate of protection. These findings further demonstrate thein vivorelevance of our previousin vitroanalyses of the SIVsmE660 challenge stock, which revealed a broad range of neutralization sensitivities of its component viruses. In sum, this report demonstrates proof-of-concept that phenotypic sieve analyses can elucidate mechanistic correlates of immune protection following vaccination and raises a cautionary note for SIV and SHIV (simian-human immunodeficiency virus) vaccine studies that employ challenge strains with envelope glycoproteins that fail to exhibit neutralization resistance profiles typical of TF viruses.IMPORTANCEWith more than 2 million new infections annually, the development of an effective vaccine against HIV-1 is a global health priority. Understanding immunologic correlates of protection generated in vaccine trials is critical to advance vaccine development. Here, we assessed the role of vaccine-elicited neutralizing antibodies in a recent nonhuman primate study of a vaccine that showed significant protection against simian immunodeficiency virus (SIV) challenge and suggested a genetic signature of neutralization sensitivity. We found that breakthrough viruses able to establish infection in vaccinated animals were substantially more resistant to antibody-mediated neutralization than were viruses from controls. These findings suggest that vaccine-elicited neutralizing antibodies selectively blocked the transmission of more sensitive challenge viruses. Sieve analysis also corroborated a genetic signature of neutralization sensitivity and highlighted the impact of challenge swarm diversity. Our findings suggest an important role for neutralization sieve analyses as an informative component of comprehensive immune-correlates analyses.

A STUDY ON THE POTENTIAL OF RIVERBANK FILTRATION FOR THE REMOVAL OF COLOR, IRON, TURBIDITY AND E.COLI IN SUNGAI PERAK, KOTA LAMA KIRI, KUALA KANGSAR, PERAK, MALAYSIA

Riverbank filtration technology in securing water resource is still new to some developing countries such as Malaysia. This research has been carried out at Kota Lama Kiri in the Kuala Kangsar, Perak, Malaysia to study the removal on the turbidity, iron, color, and E.coli by riverbank filtration. Characteristics of soil samples from pumping well (PW) was investigated. The soil samples were collected during the development and construction process of the PW. The water quality analyses were performed on site during the pumping test program. The soil samples collected were transported to the Geotechnical Engineering Laboratory, Universiti Sains Malaysia where sieve analyses and permeability test were performed with reference to BS 1377: Part 2:1990. Results of sieve analyses shows that the value of Cu (coefficient of uniformity) for the PW was found to be within the range of 2.40 to 3.75 mm while the value of Cc (coefficient of gradation) lies in the range of 0.06-0.35 mm. The ANOVA One Way Test for soil strata of the PW was performed using MINITAB statistical packages and the results indicate that the p-value was 0.996. It was found that there were no significance differences between the mean size of soil samples from different depths within the PW. The hydraulic conductivity, k value for PW ranges between 0.10-5.65 cm/s. Removal of turbidity, color, iron, and E.coli were 98.78%, 73.56%, and 87.93%, respectively. In this study, the highest removal efficiency of E.coli was found to be 100%.The overall well production from the pumping test was found 112.10 m3/hr.

The Granularity of Dust Particles when Sanding Wood and Wood-Based Materials

The article presents results of the granulometric composition of chip particles when sanding wood (beech) and wood-based materials (particleboard and semi-hardboard) using different types of sanders – wide belt sander, narrow belt sander, and hand sander. On the basis of the carried out sieve analyses, the proportion of produced particles, which can be marked as dust with the particle size of ≤ 80 μm, is high at the interval from 89.21% - 96.29 %. The highest percentage of dust particles was reached at dust from the hand disk sander. At the end of the article we point to possible technical safety measures – additional dust exhausting, suction, to possibly reduce the dust getting to the working environment.