Pub Date : 2023-03-23DOI: 10.17159/2309-8775/2023/v65n1a4
J. A. Du Plessis, S. Masule
Estimation of design flood peaks is required for the design and evaluation of hydraulic structures. Methodologies developed between the 1960s and the late 1980s, such as the Regional Maximum Flood (RMF), are used to estimate extreme flood peaks in South Africa. The RMF method uses envelope curves to estimate the maximum flood that can be expected in a specific region in South Africa and neighbouring countries, and represents an indicative upper flood limit for other flood estimation methods. The method developed by Kovacs for South Africa was last updated in 1988. Using more than 30 years of additional data for analysis, this paper highlights the RMF's perceived shortcomings. In two RMF regions, updated observed flood peaks exceeded the existing envelope curves. In 78% of the catchment areas of the evaluated stations, the station RMF values were at least 50% more than the observed maximum flood peak. When the different parameters from the Kovacs 1988 and present DWS (Department of Water and Sanitation) datasets were compared, 98% of the evaluated stations had different flood peaks recorded/reported, while 33% of the stations logged different catchment area sizes. Kovacs 1988 ratios used to estimate flood peaks at different probabilities of occurrence, using the RMF, were found to generally over-estimate expected flood peaks. It is concluded that the 1988 RMF method needs to be updated to still provide relevant guidance.
{"title":"Evaluation of Kovacs 1988 Regional Maximum Flood Method","authors":"J. A. Du Plessis, S. Masule","doi":"10.17159/2309-8775/2023/v65n1a4","DOIUrl":"https://doi.org/10.17159/2309-8775/2023/v65n1a4","url":null,"abstract":"Estimation of design flood peaks is required for the design and evaluation of hydraulic structures. Methodologies developed between the 1960s and the late 1980s, such as the Regional Maximum Flood (RMF), are used to estimate extreme flood peaks in South Africa. The RMF method uses envelope curves to estimate the maximum flood that can be expected in a specific region in South Africa and neighbouring countries, and represents an indicative upper flood limit for other flood estimation methods. The method developed by Kovacs for South Africa was last updated in 1988. Using more than 30 years of additional data for analysis, this paper highlights the RMF's perceived shortcomings. In two RMF regions, updated observed flood peaks exceeded the existing envelope curves. In 78% of the catchment areas of the evaluated stations, the station RMF values were at least 50% more than the observed maximum flood peak. When the different parameters from the Kovacs 1988 and present DWS (Department of Water and Sanitation) datasets were compared, 98% of the evaluated stations had different flood peaks recorded/reported, while 33% of the stations logged different catchment area sizes. Kovacs 1988 ratios used to estimate flood peaks at different probabilities of occurrence, using the RMF, were found to generally over-estimate expected flood peaks. It is concluded that the 1988 RMF method needs to be updated to still provide relevant guidance.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48565751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.17159/2309-8775/2023/v65n1a5
S. Khoosal, J. Smithers
There are a number of design flood estimation methods routinely used in South Africa. Flood Frequency Analysis (FFA) remains the preferred technique in instances where adequate records of observed data are available. However, in many parts of South Africa, rivers are not gauged for continuous streamflow monitoring. In the case of ungauged catchments, hydrologists and engineers generally make use of methods based on deterministic and empirical approaches for design flood estimation. Due to the limitations and performance of these methods, improved approaches need to be developed for design flood estimation in ungauged catchments. International practice has shown that making use of local information transfer from nearby gauged catchments, also referred to as donor catchments, can improve flood estimation in ungauged catchments. The main considerations for implementing such methods are the type of information transferred and selection of suitable donor catchments. Approaches for donor catchment selection include physical similarity, spatial proximity and integrated similarity. Some studies have also shown that the use of multiple donor catchments can offer further improvements. Thus, a methodology is proposed and evaluated in this paper for using local information transfer in the form of a method and location-specific adjustment factor from gauged donor catchments to improve the performance of selected deterministic and empirical flood estimation methods widely used in South Africa. The pilot study was undertaken at 48 catchments located in the north-eastern part of South Africa, with river flow data provided by the Department of Water and Sanitation. The results show that the degree of improvement for each of the methods is largely dependent on the approach used for donor catchment selection. Even though the best approach for donor catchment selection varied for the different design flood estimation methods, the integrated similarity approach performed consistently well for all methods considered. Similar to the use of single donor catchments, the results obtained from the use of multiple nearest donor catchments also varied for each of the methods used. Due to the general improvements, and the promising results and success of the simple approach used in this study, it is recommended that further refinements of the proposed methodology and approaches to donor catchment selection be considered for future research projects in order for the method to be used by engineers and hydrologists in practice.
{"title":"Evaluation of using local information from donor catchments to improve the performance of selected deterministic and empirical design flood estimation methods in South Africa","authors":"S. Khoosal, J. Smithers","doi":"10.17159/2309-8775/2023/v65n1a5","DOIUrl":"https://doi.org/10.17159/2309-8775/2023/v65n1a5","url":null,"abstract":"There are a number of design flood estimation methods routinely used in South Africa. Flood Frequency Analysis (FFA) remains the preferred technique in instances where adequate records of observed data are available. However, in many parts of South Africa, rivers are not gauged for continuous streamflow monitoring. In the case of ungauged catchments, hydrologists and engineers generally make use of methods based on deterministic and empirical approaches for design flood estimation. Due to the limitations and performance of these methods, improved approaches need to be developed for design flood estimation in ungauged catchments. International practice has shown that making use of local information transfer from nearby gauged catchments, also referred to as donor catchments, can improve flood estimation in ungauged catchments. The main considerations for implementing such methods are the type of information transferred and selection of suitable donor catchments. Approaches for donor catchment selection include physical similarity, spatial proximity and integrated similarity. Some studies have also shown that the use of multiple donor catchments can offer further improvements. Thus, a methodology is proposed and evaluated in this paper for using local information transfer in the form of a method and location-specific adjustment factor from gauged donor catchments to improve the performance of selected deterministic and empirical flood estimation methods widely used in South Africa. The pilot study was undertaken at 48 catchments located in the north-eastern part of South Africa, with river flow data provided by the Department of Water and Sanitation. The results show that the degree of improvement for each of the methods is largely dependent on the approach used for donor catchment selection. Even though the best approach for donor catchment selection varied for the different design flood estimation methods, the integrated similarity approach performed consistently well for all methods considered. Similar to the use of single donor catchments, the results obtained from the use of multiple nearest donor catchments also varied for each of the methods used. Due to the general improvements, and the promising results and success of the simple approach used in this study, it is recommended that further refinements of the proposed methodology and approaches to donor catchment selection be considered for future research projects in order for the method to be used by engineers and hydrologists in practice.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45136087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.17159/2309-8775/2023/v65n1a2
P. Stott, Z. Smith, E. Theron
Damage caused by soils subject to change in volume beneath light structures, particularly low-cost housing units of masonry construction, is unacceptably frequent. It has led to the demolition of many such units within a small fraction of their design lifespan. Perhaps the most spectacular such failure is Lerato Park in Kimberley, where the development was demolished within four years. The reason for this failure is examined in Stott and Theron (2016). The normal ways of attempting to reduce heave damage have involved increasing the strength and stiffness of foundations, together with reducing masonry panel size through movement joints and increasing the strength of the panels. While these measures have improved the situation somewhat, they are expensive and have proved to be only partially successful. This investigation examines the possibility of increasing the ability of masonry panels themselves to accommodate significant distortion without sustaining unacceptably serious cracking. The existing specifications in SANS 10164 (SANS 10164 2000) are shown to allow considerably greater inherent flexibility than current practice allows. This is dependent on the specified quality of sand (frequently ignored) and water demand requirements, as specified in South African standards, being adhered to.
{"title":"Alleviating the problem of cracking of masonry buildings on expansive clay by building flexibility into the masonry","authors":"P. Stott, Z. Smith, E. Theron","doi":"10.17159/2309-8775/2023/v65n1a2","DOIUrl":"https://doi.org/10.17159/2309-8775/2023/v65n1a2","url":null,"abstract":"Damage caused by soils subject to change in volume beneath light structures, particularly low-cost housing units of masonry construction, is unacceptably frequent. It has led to the demolition of many such units within a small fraction of their design lifespan. Perhaps the most spectacular such failure is Lerato Park in Kimberley, where the development was demolished within four years. The reason for this failure is examined in Stott and Theron (2016). The normal ways of attempting to reduce heave damage have involved increasing the strength and stiffness of foundations, together with reducing masonry panel size through movement joints and increasing the strength of the panels. While these measures have improved the situation somewhat, they are expensive and have proved to be only partially successful. This investigation examines the possibility of increasing the ability of masonry panels themselves to accommodate significant distortion without sustaining unacceptably serious cracking. The existing specifications in SANS 10164 (SANS 10164 2000) are shown to allow considerably greater inherent flexibility than current practice allows. This is dependent on the specified quality of sand (frequently ignored) and water demand requirements, as specified in South African standards, being adhered to.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42758259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.17159/2309-8775/2023/v65n1a1
C. MacRobert, T. J. Stergianos
Insufficient information is currently available to fully understand the mechanism of rod friction in DPSH (Dynamic Probe Super Heavy) probing. Consequently, a method is proposed to distinguish profiles in which friction results in excessive blow counts based on normalised profiles. While friction-impacted DPSH profiles are difficult to interpret, those unaffected by friction show better equivalence to SPT (Standard Penetration Test) profiles, especially if used to screen for competent (SPT blow counts > 30) ground conditions.
目前还没有足够的信息来充分了解DPSH (Dynamic Probe Super Heavy)探测中的杆摩擦机制。因此，提出了一种方法来区分轮廓，其中摩擦导致过多的打击计数基于归一化轮廓。虽然受摩擦影响的DPSH剖面很难解释，但未受摩擦影响的DPSH剖面与SPT(标准侵透测试)剖面表现出更好的等效性，特别是用于筛选合格的(SPT冲击计数为100 - 30)地面条件。
{"title":"Establishing competent ground conditions with the DPSH","authors":"C. MacRobert, T. J. Stergianos","doi":"10.17159/2309-8775/2023/v65n1a1","DOIUrl":"https://doi.org/10.17159/2309-8775/2023/v65n1a1","url":null,"abstract":"Insufficient information is currently available to fully understand the mechanism of rod friction in DPSH (Dynamic Probe Super Heavy) probing. Consequently, a method is proposed to distinguish profiles in which friction results in excessive blow counts based on normalised profiles. While friction-impacted DPSH profiles are difficult to interpret, those unaffected by friction show better equivalence to SPT (Standard Penetration Test) profiles, especially if used to screen for competent (SPT blow counts > 30) ground conditions.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42117027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-13DOI: 10.17159/2309-8775/2022/v64n4a2
G. M. Mvelase, J. Anochie-Boateng, P. Gräbe
The performance of railway track structure is influenced by the ballast shape properties including roundness, flatness, elongation, sphericity, angularity and surface texture. The challenge is how to accurately measure the irregular shapes of ballast materials and directly link them to performance. In this paper, a modern three-dimensional laser technique was used to determine shapes of freshly produced crushed ballast and recycled ballast sampled from the heavy-haul coal line in South Africa. The objective was to investigate the effect of ballast shapes on settlement (i.e. permanent deformation). All five ballast materials were scanned in the three-dimensional laser scanning system and the data collected was processed to reconstruct three-dimensional models of the ballast particles. The results obtained were used to develop a chart to classify ballast shapes and link these shapes physically with settlement determined from a triaxial testing programme. Based on the triaxial test results, new empirical models were developed to determine settlement on the route corridor of the heavy-haul coal line. It is anticipated that outcomes of this study would assist with quality assessments and railway ballast maintenance in the field.
{"title":"Application of a modern laser technique to evaluate the performance of recycled railway ballast","authors":"G. M. Mvelase, J. Anochie-Boateng, P. Gräbe","doi":"10.17159/2309-8775/2022/v64n4a2","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n4a2","url":null,"abstract":"The performance of railway track structure is influenced by the ballast shape properties including roundness, flatness, elongation, sphericity, angularity and surface texture. The challenge is how to accurately measure the irregular shapes of ballast materials and directly link them to performance. In this paper, a modern three-dimensional laser technique was used to determine shapes of freshly produced crushed ballast and recycled ballast sampled from the heavy-haul coal line in South Africa. The objective was to investigate the effect of ballast shapes on settlement (i.e. permanent deformation). All five ballast materials were scanned in the three-dimensional laser scanning system and the data collected was processed to reconstruct three-dimensional models of the ballast particles. The results obtained were used to develop a chart to classify ballast shapes and link these shapes physically with settlement determined from a triaxial testing programme. Based on the triaxial test results, new empirical models were developed to determine settlement on the route corridor of the heavy-haul coal line. It is anticipated that outcomes of this study would assist with quality assessments and railway ballast maintenance in the field.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42653860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-13DOI: 10.17159/2309-8775/2022/v64n4a4
R. Ambunda, M. Sinclair
This study was designed to explore the combinational effect of the roadway and traffic characteristics of national rural roads on fatal and serious-injury crashes in Namibia. Namibia, like many other countries in Southern Africa, experiences high numbers of high-severity crashes, particularly on its rural road network. The study applied Generalised Poisson regression models to analyse the study dataset. The results indicate that high-severity crashes are almost always influenced by a combination of factors, not simply the presence of a single factor. For example, on higher-order roads, a higher proportion of heavy vehicles in the traffic stream had the highest absolute impact on high-severity crash levels, but this effect was heightened when hilliness, wider lanes, surfaced shoulders and higher operating speeds were also present at the same time. On lower-order roads a higher proportion of light vehicles in the traffic stream had the highest absolute impact on high-severity crashes, and again this was compounded in the presence of wider unpaved shoulder widths and higher operating speeds. Overall, wider lane widths and wider unpaved shoulder widths, especially when found in combination with each other, were linked to a subsequent increase in higher-severity crash levels on higher-order roads. The study shows conclusively that the development of safer roads relies not on simply implementing minimum safety standards for individual design elements, but on understanding the relationship between features of road design, traffic parameters and road safety, to recognise which coincidences of factors affect crash risks on different classes of road. This knowledge can result in more careful road design so that crash likelihood is reduced.
{"title":"Traffic safety and the rural road environment: Assessing the impact of combined roadway conditions on crash incidence","authors":"R. Ambunda, M. Sinclair","doi":"10.17159/2309-8775/2022/v64n4a4","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n4a4","url":null,"abstract":"This study was designed to explore the combinational effect of the roadway and traffic characteristics of national rural roads on fatal and serious-injury crashes in Namibia. Namibia, like many other countries in Southern Africa, experiences high numbers of high-severity crashes, particularly on its rural road network. The study applied Generalised Poisson regression models to analyse the study dataset. The results indicate that high-severity crashes are almost always influenced by a combination of factors, not simply the presence of a single factor. For example, on higher-order roads, a higher proportion of heavy vehicles in the traffic stream had the highest absolute impact on high-severity crash levels, but this effect was heightened when hilliness, wider lanes, surfaced shoulders and higher operating speeds were also present at the same time. On lower-order roads a higher proportion of light vehicles in the traffic stream had the highest absolute impact on high-severity crashes, and again this was compounded in the presence of wider unpaved shoulder widths and higher operating speeds. Overall, wider lane widths and wider unpaved shoulder widths, especially when found in combination with each other, were linked to a subsequent increase in higher-severity crash levels on higher-order roads. The study shows conclusively that the development of safer roads relies not on simply implementing minimum safety standards for individual design elements, but on understanding the relationship between features of road design, traffic parameters and road safety, to recognise which coincidences of factors affect crash risks on different classes of road. This knowledge can result in more careful road design so that crash likelihood is reduced.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41862365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-13DOI: 10.17159/2309-8775/2022/v64n4a3
S. Calitz, J. Wium
The value of Building Information Modelling (BIM) has been noted by the global construction industry, and several countries are facilitating BIM through national strategies and initiatives. However, the South African Construction Industry (SACI) lacks widespread and effective BIM implementation. Therefore, this study presents a proposal to facilitate BIM implementation across the industry. A qualitative, exploratory methodology was followed involving semi-structured interviews with nine BIM experts. The interviews were analysed using thematic analysis. An understanding was gained of the challenges associated with BIM implementation across the construction industry. Possible solutions were found in terms of initiatives and strategies to facilitate and promote BIM implementation locally. Key role-players responsible for facilitating BIM implementation in the SACI were identified. Finally, a proposal is made to facilitate BIM implementation across the local industry, which comprises three key concepts, namely leadership, strategy, and roles and responsibilities. This research contributes to BIM adoption and implementation in the SACI and can be used for future research on national BIM implementation strategies.
{"title":"A proposal to facilitate BIM implementation across the South African construction industry","authors":"S. Calitz, J. Wium","doi":"10.17159/2309-8775/2022/v64n4a3","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n4a3","url":null,"abstract":"The value of Building Information Modelling (BIM) has been noted by the global construction industry, and several countries are facilitating BIM through national strategies and initiatives. However, the South African Construction Industry (SACI) lacks widespread and effective BIM implementation. Therefore, this study presents a proposal to facilitate BIM implementation across the industry. A qualitative, exploratory methodology was followed involving semi-structured interviews with nine BIM experts. The interviews were analysed using thematic analysis. An understanding was gained of the challenges associated with BIM implementation across the construction industry. Possible solutions were found in terms of initiatives and strategies to facilitate and promote BIM implementation locally. Key role-players responsible for facilitating BIM implementation in the SACI were identified. Finally, a proposal is made to facilitate BIM implementation across the local industry, which comprises three key concepts, namely leadership, strategy, and roles and responsibilities. This research contributes to BIM adoption and implementation in the SACI and can be used for future research on national BIM implementation strategies.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41322321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-13DOI: 10.17159/2309-8775/2022/v64n4a1
F. Sinngu, S. Ekolu, A. Naghizadeh, H. Quainoo
The present study investigated the performance of South African natural zeolite for potential use as a cement extender. To the best knowledge of the authors, the natural zeolite studied has not been employed before as pozzolan in the cement industry, and its proposed use would be new in concrete construction. In the investigation, mortar mixtures were prepared using ordinary Portland cement CEM I 52,5N blended with 0, 10, 20 and 30% natural zeolite. The effectiveness of natural zeolite was also compared with performance results of mixtures containing 30% fly ash. The tests conducted were workability, compressive strength, pozzolanic activity with lime, drying shrinkage, alkali-silica reaction, and sulphate resistance. Analytical studies were done using X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. It was found that, while incorporation of natural zeolite in cement reduces workability, its effects on mechanical properties and on durability characteristics were superior to those of fly ash, as the former effectively enhanced long-term strength and mitigated drying shrinkage, alkali-silica reaction and sulphate attack. Incorporation of 20% natural zeolite in cement gave an effective overall performance, meeting the ASTM C618 (2015) criteria for Class N pozzolan. Based on EN 197-1 (2000) / SANS 50197-1 (2013), the blend of natural zeolite and ordinary Portland cement met the criteria for its classification as CEM II/A-P 32.5N,R cement type.
本研究考察了南非天然沸石作为水泥扩展剂的潜在用途。据作者所知，所研究的天然沸石以前从未在水泥工业中用作沸石，而其在混凝土施工中的应用将是新的。在研究中，用普通硅酸盐水泥CEM I 52、5N与0、10、20、30%天然沸石混合配制砂浆。并将天然沸石的效能与30%粉煤灰混合料的效能进行了比较。进行了和易性、抗压强度、与石灰的火山灰活性、干燥收缩率、碱-硅反应和耐硫酸盐性等试验。利用x射线衍射、扫描电镜和能量色散光谱进行了分析研究。研究发现，天然沸石掺入水泥虽然降低了水泥的和易性，但其对水泥力学性能和耐久性的影响优于粉煤灰，因为前者有效地提高了水泥的长期强度，减轻了水泥的干燥收缩、碱-硅反应和硫酸盐侵蚀。在水泥中掺入20%的天然沸石具有有效的整体性能，符合ASTM C618 (2015) N级火山灰的标准。根据EN 197-1 (2000) / SANS 50197-1(2013)，天然沸石与普通硅酸盐水泥的共混物符合CEM II/A-P 32.5N,R水泥类型的分类标准。
{"title":"Experimental study and classification of natural zeolite pozzolan for cement in South Africa","authors":"F. Sinngu, S. Ekolu, A. Naghizadeh, H. Quainoo","doi":"10.17159/2309-8775/2022/v64n4a1","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n4a1","url":null,"abstract":"The present study investigated the performance of South African natural zeolite for potential use as a cement extender. To the best knowledge of the authors, the natural zeolite studied has not been employed before as pozzolan in the cement industry, and its proposed use would be new in concrete construction. In the investigation, mortar mixtures were prepared using ordinary Portland cement CEM I 52,5N blended with 0, 10, 20 and 30% natural zeolite. The effectiveness of natural zeolite was also compared with performance results of mixtures containing 30% fly ash. The tests conducted were workability, compressive strength, pozzolanic activity with lime, drying shrinkage, alkali-silica reaction, and sulphate resistance. Analytical studies were done using X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. It was found that, while incorporation of natural zeolite in cement reduces workability, its effects on mechanical properties and on durability characteristics were superior to those of fly ash, as the former effectively enhanced long-term strength and mitigated drying shrinkage, alkali-silica reaction and sulphate attack. Incorporation of 20% natural zeolite in cement gave an effective overall performance, meeting the ASTM C618 (2015) criteria for Class N pozzolan. Based on EN 197-1 (2000) / SANS 50197-1 (2013), the blend of natural zeolite and ordinary Portland cement met the criteria for its classification as CEM II/A-P 32.5N,R cement type.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67483415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-14DOI: 10.17159/2309-8775/2022/v64n3a5
P. de Jager, K. Wall
The 2006, 2011 and 2017 Report Cards on the condition of built environment fixed infrastructure in South Africa were the product of cooperation between the Council for Scientific and Industrial Research (CSIR) and the South African Institution of Civil Engineering (SAICE). Their purpose has been to draw the attention of government, and of the public at large, to the importance of maintenance, and to factors underlying the condition of public sector infrastructure. One of the ten public infrastructure sectors assessed in all three report cards was the health sector, comprising hospitals and clinics. This paper describes how the collection and analysis for the 2017 infrastructure report card of health sector condition data was conducted. In particular, it describes how, in the absence of a comprehensive reasonably up-to-date database, and the way, without their interrogation and integration in mind, in which available datasets had been compiled, the CSIR formulated a pragmatic derivative method to assess the condition of the public health built infrastructure portfolio.
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Pub Date : 2022-09-14DOI: 10.17159/2309-8775/2022/v64n3a2
A. Way, N. de Koker, C. Viljoen
Currently, there are no recommendations of target reliability for new-build road bridges tailored to developing countries. Target reliabilities in existing international literature reflect the economic and social circumstances associated with developed countries and may not be economically or societally acceptable for South Africa. This research determines target reliability for new-build road bridges specifically for a South African context. Economic cost optimisation and a societal risk approach are considered. Cost optimisation considers the cost of safety and consequences of failure. The life quality index methodology is used to consider limits on target reliability from a societal risk perspective. Additionally, the effect of structural redundancy on target reliability in bridges is investigated. Target reliabilities from cost optimisation are shown to be slightly higher than those from SANS 10160-1 and correspond with those from ISO 2394:2015. Recommendations of annual target reliability for new-build road bridges in South Africa are proposed - a typical value of β = 4.2 is recommended. Societal limits on target reliability correspond with target reliability from cost optimisation for bridges with minor consequences of failure and do not govern new-build bridges in South Africa. Target reliability reduces with increasing measures of bridge redundancy; a means by which to consider the effect of structural redundancy on target reliability is also proposed.
{"title":"Target reliability for new road bridges in South Africa","authors":"A. Way, N. de Koker, C. Viljoen","doi":"10.17159/2309-8775/2022/v64n3a2","DOIUrl":"https://doi.org/10.17159/2309-8775/2022/v64n3a2","url":null,"abstract":"Currently, there are no recommendations of target reliability for new-build road bridges tailored to developing countries. Target reliabilities in existing international literature reflect the economic and social circumstances associated with developed countries and may not be economically or societally acceptable for South Africa. This research determines target reliability for new-build road bridges specifically for a South African context. Economic cost optimisation and a societal risk approach are considered. Cost optimisation considers the cost of safety and consequences of failure. The life quality index methodology is used to consider limits on target reliability from a societal risk perspective. Additionally, the effect of structural redundancy on target reliability in bridges is investigated. Target reliabilities from cost optimisation are shown to be slightly higher than those from SANS 10160-1 and correspond with those from ISO 2394:2015. Recommendations of annual target reliability for new-build road bridges in South Africa are proposed - a typical value of β = 4.2 is recommended. Societal limits on target reliability correspond with target reliability from cost optimisation for bridges with minor consequences of failure and do not govern new-build bridges in South Africa. Target reliability reduces with increasing measures of bridge redundancy; a means by which to consider the effect of structural redundancy on target reliability is also proposed.","PeriodicalId":54762,"journal":{"name":"Journal of the South African Institution of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44044779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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