SOUTH AFRICA â CONCRETE CONSTRUCTION INDUSTRY ...
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
SOUTH AFRICA – CONCRETE CONSTRUCTION INDUSTRY - CEMENT BASED MATERIALS AND CIVIL INFRASTRUCTURE (CBM -CI) Dr. Yunus Ballim Prof. Department of Civil Engineering University of the Witwatersrand Johannesburg SOUTH AFRICA ABSTRACT: This paper presents an overview of the cement and concrete construction sector in South Africa. In particular, the paper focuses on the size and extent of the cement and concrete sector, the raw materials and manufacturing issues that characterize the sector, and the state of research, development and application of new technology in the country. A particular focus of research in South Africa has been in the areas of concrete durability, deterioration and rehabilitation studies. What emerges from this overview is that the challenges facing the cement and concrete sector in South Africa are largely focused on its capacity for supply of materials (raw and processed) and development of high-level human resources skills. The country faces an increasing sophistication in the technology and application of cement-based materials that is becoming increasingly less tolerant of poor manufacturing practices. A strong base of high-level human resource skills will be necessary to maximize the benefits of these developments.
1.
INTRODUCTION
This paper explores the development of the cement and concrete industry in South Africa and its contribution to both regional infrastructure developments as well as to the general body of knowledge of cement and concrete technology. Given the relatively short time of its engagement with cement, South African researchers have made important contributions to international understanding of the fundamental and engineering behaviour of these materials. Cement production in South Africa started in 1892 when the Eerste Cement-Fabrieken, Beperkt (First Cement Factory, Limited) was established near a dolomitic limestone deposit outside Pretoria. This was a ring oven plant that produced about 1000 tons of cement in its first year of operation. The first rotary kiln was brought into commission in 1904, and the rapid industrial expansion of the 1960s and 1970s saw production output grow to around 7 million tons per annum. This demand growth was driven by a rapid pace of urbanisation 137
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
and infrastructure development, racially skewed by the “geo-political imagination” of apartheid planners. The result of this period of growth is that, relative to countries in the developing world, South Africa has a large stock of concrete infrastructure that in many cases is aging and in need of repair and rehabilitation. South Africa is presently home to around 47 million people with a gross domestic product of US$ 180 billion. Levels of literacy and education are not particularly favorable, and it is generally acknowledged that an important limit to growth is the low availability of technical skills ranging from artisan levels to high-level science and engineering competence. This dearth is also acute in the general areas of high-level research and technology application skills in cement and concrete materials science and engineering. As mentioned, this paper is intended as an overview of the state of cement and concrete technology in South Africa. Its primary purpose is to provide a basis for discussion with cement and concrete specialists from other countries to consider the opportunities for joint approaches to addressing the challenges facing the role of concrete in infrastructure development across the world.
2.
CEMENT PRODUCTION AND CONSUMPTION
Figure 2.1 shows the growth in cement production in South Africa over the period 1892 to 2002. This figure shows the effect of the intensive industrial development during the period 1960 to 1975 in driving cement production. Over the period shown in Figure 2.1, the number of clinker production plants grew from one to eleven. There are also a further nine clinker milling and blending plants across the country, and, in 2005, the total cement output was 13 million tons. Due to the award of the 2010 soccer world cup together with a general increase in industrial activity, cement and concrete consumption is already on the rise and, in some cases, cement clinker is being imported to enhance supply. Cement production capacity is also currently being expanded.
Figure 2.1
Growth in cement production in South Africa (1892 to 2002) [1]. 138
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
Figure 2.2 shows cement consumption patterns by industrial sector. Compared to most other industrialised countries, Figure 2.2 shows that the ready-mixed concrete sector is relatively underdeveloped in South Africa. Also, approximately 50% of the cement produced goes to resellers and retail outlets to be used in on-site manual and mechanical mixing. South Africa also has a well-developed industrial sector that provides cement extender materials. In 2005, approximately 750,000 tons of GGBS and 182,000 tons of fly ash were sold. Steel slag is generally of the blast furnace type of material, but a recently commissioned steel plant on the west coast of the country has been producing slag from a corex process that has significantly enhanced hydration properties compared to the blast furnace materials.
Figure 2.2 Cement consumption by the industrial sector [2].
3. CHARACTERISTICS OF CONCRETE MATERIALS South Africa produces cements and other primary concrete making materials that satisfy the requirements of appropriate Euro-code (EN) specifications. Figure 3.1 shows the typical chemical composition, Bogue mineralogical analysis, and a range of adiabatic heat profiles for South African clinker cements.
139
CBM-CI International Workshop, Karachi, Pakistan
Figure 3.1
Dr. Y. Ballim
Adiabatic heat and chemical composition characteristics of local cements [3].
Almost all the concrete aggregates used in South Africa are derived from quarried and crushed parent rock materials. In some areas, natural sands are available in sufficient quantities, but there is an almost complete absence of natural coarse aggregates. This means that concretes in South Africa tend to be quite harsh with relatively high water demands. There are two notable aggregate problems in the country: (i) there are a range of aggregates, particularly in the Johannesburg and Western Cape regions, that are sensitive to the alkali silica reaction to varying degrees [4]; and (ii) aggregates from the drier north-central regions show high shrinkage upon drying [5]. Nevertheless, both these aggregate characteristics are well documented, and suitable material selection and design countermeasures are routinely implemented.
4.
RESEARCH AND TECHNOLOGY DEVELOPMENT
Researchers in South Africa have made important contributions to developments in cement and concrete technology [4]. These contributions have been in both the materials and structural engineering aspects of the use of concrete. However, research activities in the field of materials engineering have recently shifted strongly toward deterioration and durability studies. The main environmental threat to concrete durability is a long marine coastline characterised by high winds. Chloride-induced corrosion is therefore an important research activity. In inland environments, carbonation, ASR and sulphate attack present particular problems, and research activities reflect the importance of these problems. Over the last five years, South Africa has seen a strong shift towards performance-based specifications for concrete using locally developed test methods such as oxygen permeability, 140
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
water sorptivity and chloride conductivity [6]. This approach is in the final stages of development with a number of major construction projects already having included the test methods in their specifications. A draft national standard specification for the test methods has already been produced.
5.
SUMMARY
The cement and concrete sector is mature in South Africa in both the development and application of technology. Perhaps the greatest threat to the future of the sector is in the significant shortage of high-level human resources and skills for the further development, refinement and utilization of concrete. This is the responsibility of university and training institutions and will require significant time and financial investments. REFERENCES [1] [2] [3] [4] [5] [6]
Cement and Concrete Institute, Midrand, Johannesburg. Information database, March 2007. Cement and Concrete Institute Annual Report, C&CI, Midrand, 2006. Ballim, Y and Graham, PC. Early-age heat evolution of clinker cements in relation to microstructure and composition: implications for temperature development in large concrete elements. Cement and Concrete Composites, vol. 26, 2004, pp 417-426 Addis, BJ and Owen, G (Eds). Fulton's Concrete Technology, 8th (rev.) ed., Cement and Concrete Institute, Midrand, 2001 Roper, H. Shrinking Aggregates in concrete. National Building Research Institute, CSIR, South Africa, 1959. Alexander, MG, Stanish, K and Y Ballim, Y. A two-level approach to performance-based durability specifications for corrosion prevention. International RILEM-JCI Seminar on Concrete Durability and Service Life Planning, Dead Sea, Israel, 15-16 March 2006.
141
Dr. Y. Ballim
SOUTH AFRICA – CONCRETE CONSTRUCTION INDUSTRY - CEMENT BASED MATERIALS AND CIVIL INFRASTRUCTURE (CBM -CI) Dr. Yunus Ballim Prof. Department of Civil Engineering University of the Witwatersrand Johannesburg SOUTH AFRICA ABSTRACT: This paper presents an overview of the cement and concrete construction sector in South Africa. In particular, the paper focuses on the size and extent of the cement and concrete sector, the raw materials and manufacturing issues that characterize the sector, and the state of research, development and application of new technology in the country. A particular focus of research in South Africa has been in the areas of concrete durability, deterioration and rehabilitation studies. What emerges from this overview is that the challenges facing the cement and concrete sector in South Africa are largely focused on its capacity for supply of materials (raw and processed) and development of high-level human resources skills. The country faces an increasing sophistication in the technology and application of cement-based materials that is becoming increasingly less tolerant of poor manufacturing practices. A strong base of high-level human resource skills will be necessary to maximize the benefits of these developments.
1.
INTRODUCTION
This paper explores the development of the cement and concrete industry in South Africa and its contribution to both regional infrastructure developments as well as to the general body of knowledge of cement and concrete technology. Given the relatively short time of its engagement with cement, South African researchers have made important contributions to international understanding of the fundamental and engineering behaviour of these materials. Cement production in South Africa started in 1892 when the Eerste Cement-Fabrieken, Beperkt (First Cement Factory, Limited) was established near a dolomitic limestone deposit outside Pretoria. This was a ring oven plant that produced about 1000 tons of cement in its first year of operation. The first rotary kiln was brought into commission in 1904, and the rapid industrial expansion of the 1960s and 1970s saw production output grow to around 7 million tons per annum. This demand growth was driven by a rapid pace of urbanisation 137
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
and infrastructure development, racially skewed by the “geo-political imagination” of apartheid planners. The result of this period of growth is that, relative to countries in the developing world, South Africa has a large stock of concrete infrastructure that in many cases is aging and in need of repair and rehabilitation. South Africa is presently home to around 47 million people with a gross domestic product of US$ 180 billion. Levels of literacy and education are not particularly favorable, and it is generally acknowledged that an important limit to growth is the low availability of technical skills ranging from artisan levels to high-level science and engineering competence. This dearth is also acute in the general areas of high-level research and technology application skills in cement and concrete materials science and engineering. As mentioned, this paper is intended as an overview of the state of cement and concrete technology in South Africa. Its primary purpose is to provide a basis for discussion with cement and concrete specialists from other countries to consider the opportunities for joint approaches to addressing the challenges facing the role of concrete in infrastructure development across the world.
2.
CEMENT PRODUCTION AND CONSUMPTION
Figure 2.1 shows the growth in cement production in South Africa over the period 1892 to 2002. This figure shows the effect of the intensive industrial development during the period 1960 to 1975 in driving cement production. Over the period shown in Figure 2.1, the number of clinker production plants grew from one to eleven. There are also a further nine clinker milling and blending plants across the country, and, in 2005, the total cement output was 13 million tons. Due to the award of the 2010 soccer world cup together with a general increase in industrial activity, cement and concrete consumption is already on the rise and, in some cases, cement clinker is being imported to enhance supply. Cement production capacity is also currently being expanded.
Figure 2.1
Growth in cement production in South Africa (1892 to 2002) [1]. 138
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
Figure 2.2 shows cement consumption patterns by industrial sector. Compared to most other industrialised countries, Figure 2.2 shows that the ready-mixed concrete sector is relatively underdeveloped in South Africa. Also, approximately 50% of the cement produced goes to resellers and retail outlets to be used in on-site manual and mechanical mixing. South Africa also has a well-developed industrial sector that provides cement extender materials. In 2005, approximately 750,000 tons of GGBS and 182,000 tons of fly ash were sold. Steel slag is generally of the blast furnace type of material, but a recently commissioned steel plant on the west coast of the country has been producing slag from a corex process that has significantly enhanced hydration properties compared to the blast furnace materials.
Figure 2.2 Cement consumption by the industrial sector [2].
3. CHARACTERISTICS OF CONCRETE MATERIALS South Africa produces cements and other primary concrete making materials that satisfy the requirements of appropriate Euro-code (EN) specifications. Figure 3.1 shows the typical chemical composition, Bogue mineralogical analysis, and a range of adiabatic heat profiles for South African clinker cements.
139
CBM-CI International Workshop, Karachi, Pakistan
Figure 3.1
Dr. Y. Ballim
Adiabatic heat and chemical composition characteristics of local cements [3].
Almost all the concrete aggregates used in South Africa are derived from quarried and crushed parent rock materials. In some areas, natural sands are available in sufficient quantities, but there is an almost complete absence of natural coarse aggregates. This means that concretes in South Africa tend to be quite harsh with relatively high water demands. There are two notable aggregate problems in the country: (i) there are a range of aggregates, particularly in the Johannesburg and Western Cape regions, that are sensitive to the alkali silica reaction to varying degrees [4]; and (ii) aggregates from the drier north-central regions show high shrinkage upon drying [5]. Nevertheless, both these aggregate characteristics are well documented, and suitable material selection and design countermeasures are routinely implemented.
4.
RESEARCH AND TECHNOLOGY DEVELOPMENT
Researchers in South Africa have made important contributions to developments in cement and concrete technology [4]. These contributions have been in both the materials and structural engineering aspects of the use of concrete. However, research activities in the field of materials engineering have recently shifted strongly toward deterioration and durability studies. The main environmental threat to concrete durability is a long marine coastline characterised by high winds. Chloride-induced corrosion is therefore an important research activity. In inland environments, carbonation, ASR and sulphate attack present particular problems, and research activities reflect the importance of these problems. Over the last five years, South Africa has seen a strong shift towards performance-based specifications for concrete using locally developed test methods such as oxygen permeability, 140
CBM-CI International Workshop, Karachi, Pakistan
Dr. Y. Ballim
water sorptivity and chloride conductivity [6]. This approach is in the final stages of development with a number of major construction projects already having included the test methods in their specifications. A draft national standard specification for the test methods has already been produced.
5.
SUMMARY
The cement and concrete sector is mature in South Africa in both the development and application of technology. Perhaps the greatest threat to the future of the sector is in the significant shortage of high-level human resources and skills for the further development, refinement and utilization of concrete. This is the responsibility of university and training institutions and will require significant time and financial investments. REFERENCES [1] [2] [3] [4] [5] [6]
Cement and Concrete Institute, Midrand, Johannesburg. Information database, March 2007. Cement and Concrete Institute Annual Report, C&CI, Midrand, 2006. Ballim, Y and Graham, PC. Early-age heat evolution of clinker cements in relation to microstructure and composition: implications for temperature development in large concrete elements. Cement and Concrete Composites, vol. 26, 2004, pp 417-426 Addis, BJ and Owen, G (Eds). Fulton's Concrete Technology, 8th (rev.) ed., Cement and Concrete Institute, Midrand, 2001 Roper, H. Shrinking Aggregates in concrete. National Building Research Institute, CSIR, South Africa, 1959. Alexander, MG, Stanish, K and Y Ballim, Y. A two-level approach to performance-based durability specifications for corrosion prevention. International RILEM-JCI Seminar on Concrete Durability and Service Life Planning, Dead Sea, Israel, 15-16 March 2006.
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