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The purpose of this paper is to describe sustainability of hollow and solid blocks in sub-Saharan Africa.

Indicators of stakeholder value are proposed for measuring block sustainability based on comparisons of user building value price and carbon emissions. Block manufacturing processes in Tanzania and Uganda are described and assessed in this context.

The results from Uganda indicate that there are economic and environmental advantages in using hollow blocks as long as they are produced to statutory compliance levels. However, where blocks are not produced to standard requirements, the results indicate that it is better to use solid blocks. This surprising result seems to indicate that blocks prepared using low additions of cement might have sufficient functional quality for simple residential building applications even though they might not meet current standard strength requirements and have low cement productivity. These results also indicate that the improvement potential indicated previously cannot be realised when hollow blocks are used for simple construction needs.

Clear benchmarks for the best practical level of cement block sustainability seem to be missing. The first reasons is that the lowest acceptable compressive strength has not been defined since standard requirements might not be relevant in the studied context. The second one is that the lowest possible practically achievable cement content with acceptable cement productivity has not been established.

Understanding sustainability can be very difficult and substantial work needs to be done to introduce operational sustainability indicators.

The results contribute to the discussion of understanding, defining and measuring sustainability.

This work aims to demonstrate the use of electrochemical chloride extraction (ECE) to remove chloride ions away from the steel rebar in chloride-contaminated mortar and to mitigate the corrosion of the embedded steel.

To simulate salt contamination in concrete, sodium chloride was added at 0.5 per cent by weight of cement in the fresh mortar featuring a water-to-cement ratio of 0.45. The ECE treatments were varied at two electrical current densities (1 and 5 A/m²), using two electrolytes (0.1M NaOH and 0.1M Na₃BO₃ solutions) and for two periods (2 and 4 weeks). The average free chloride concentration in cement mortars before and after ECE treatment was quantified using a customized chloride sensor, whereas the spatial distribution of relevant elements was obtained using energy-dispersive X-ray spectroscopy. The effect of ECE treatment on the electric resistivity of mortar and the corrosion resistance of steel rebar was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements, respectively.

The experimental results reveal that the ECE treatment was effective in removing chlorides and in improving electric resistivity and compressive strength of the mortar, when using the sodium borate solution as the electrolyte. In this case, a 4-week ECE treatment at 1 A/m² decreased the free chloride content in the mortar by 70 per cent, significantly increased the Ca/Si ratio in the mortar near rebar, led to a more refined and less permeable microstructure of the mortar and significantly improved its compressive strength. The ECE treatment was able to halt the chloride-induced corrosion of steel rebar by passivation. A 4-week ECE treatment at 1 A/m² using sodium hydroxide and sodium borate solutions decreased the corrosion rate of rebar by 36 and 34 per cent, respectively.

This electrochemical rehabilitation of steel-reinforced concrete under chloride-contaminated condition is very effective in prolonging its service life.

The purpose of this paper is to discuss the roadmapping methodology and its application to concrete prefabricated housing in Australia.

The paper describes the concrete and housing industries of Australia collaboration in a project to develop a technology and innovation roadmap that will advance the concrete industry's supply chain capabilities by identifying and mapping innovation necessary for prefabricated concrete house construction. The roadmap lays out what is necessary for an off‐site systems‐based approach to housing construction in Australia. The systems‐based approach to prefabricated concrete products is a relatively new and developing extension of the concrete industry supply chain in Australia. New manufacturing technologies and innovations, which are emerging locally and from overseas, make these potential extensions possible. For the long‐term sustainability of the concrete industry, it is critical that it better understands how to adopt cooperative innovations in prefabrication to realise these benefits in the housing industry and advance Australia's competitiveness. The first phase of the mapping involved the development of an industry‐maturity model that determined the current state of the industry, and plotted this against the desired route for the future. Numerous industry‐based workshops and interviews gathered the views of the industry towards existing concrete housing systems, and where their main difficulties are in relation to adoption. Using these data, a technology roadmap is developed, together with three options on how these might be realised using the roadmap. The options offered through the roadmapping process form the basis for ongoing experimental trials of concrete houses in the major cities of Australia.

The system‐based approach to prefabrication is seen as innovative and the industry needs to understand how to adopt cooperative innovations in prefabrication in order to be competitive.

The paper offers insights into the technology roadmapping process in Australia, offering an exciting prospect for moving the industry into a new model of delivery.

This study aims to investigate the properties of mortar made from a bottom ash substitute as a sustainable construction material. It is believed that the use of cement in concrete construction contributes to the release of carbon dioxide into the atmosphere, which has been a consistent increase in recent years. The utilization of bottom ash waste is expected to reduce pollution associated with cement production.

Bottom ash is used as replacement materials for cement and fine aggregate in the manufacture of mortar. Bottom ash substituted for cement of 10%, 20% and 30% of the total weight of the binder, whereas bottom ash substituted for the fine aggregate of 30%, 40% and 50% of the total weight of the sand. Binder properties were determined using scanning electron microscopy and energy dispersive X-ray. Meanwhile, the fresh properties (slump flow) and hardened properties were determined (compressive strength and mass density). In the hardened properties test, two types of curing were used: water and sealed curing.

The compressive strength of mortar decreased as the amount of bottom ash as cement replacement. However, the compressive strength increased when bottom ash was used as aggregate replacement. Additionally, bottom ash was sufficient as a substitute for fine aggregate than as a substitute for cement.

This research presents test results that are more straightforward to apply in the construction site.

The purpose of this paper is to examine the effect of various polypropylene fibre additions (types and volume) to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires.

Medium strength concrete was manufactured with varying proportions of polypropylene fibres. Plain control samples were used to determine the original concrete strength and this was used as a benchmark following high temperature heat tests to evaluate the surface condition and final compressive strength. A pilot study was used to determine an appropriate heat source for the test. This was three Bunsen burners, however sufficient heat could not be generated within 150 mm concrete cubes and the concrete was shown to be a significant insulator and fire protection for structural members. The concrete test cubes were tested in a saturated condition which may reflect conditions where concrete is used in an external environment and thus is subject to soaking.

One hundred and fifty millimetre concrete cubes with and without fibres were placed into a furnace at 1,000°C. Explosive spalling was shown to be reduced with the use of polypropylene fibres but the final compressive strength of concrete was significantly reduced and had little residual structural value after a two hour period of heating.

As the concrete tested was saturated, this condition provided a worst case scenario with regards to the build up of hydrostatic and vapour pressure within the cube. A range of percentage moisture contents would produce a more evenly balanced view of the effects of fibres in concrete. A single grade of concrete was used for the test. As the permeability of concrete influences the rate at which steam can escape from the interior of a saturated concrete cube, testing a range of concrete strengths would show this aspect of material performance with regard to spalling and final residual strength. Further research is recommended with regard to moisture contents, strengths of concrete and a range of temperatures.

This research has significance for the designer, in that buildings subject to terrorist activity may suffer from impact damage and an outbreak of fire following the initial attack.

The use of polypropylene fibres in concrete to provide anti spalling qualities is relatively new and this research adds to the knowledge regarding fibre type and volume with regard to first spall time, total area and number of areas subject to spalling and the final compressive strength of concrete following two hours of raised temperatures.

This study aims to present the results of an experimental evaluation of low (M30), mid (M40) and high (M50) grade self-compacting concrete (SCC) with three nominal maximum aggregate sizes (NMAS), namely, 20 mm, 16 mm and 12.5 mm, with Bailey gradation (BG) in comparison with Indian standard gradation (ISG).

This study was conducted in a laboratory by testing the characteristics of fresh and hardened properties of self-compacting concrete.

Rheological and mechanical properties of SCC were evaluated in detail and according to the results, a concrete sample containing lower NMAS with BG demonstrated improvement in modulus of elasticity and compressive strength, while improving the rheological properties as well. Meanwhile, SCC demonstrated poor performance in split tensile and flexural strengths with lower NMAS gradations and a direct correlation was evident as the increase in NMAS caused an increase in the strength and vice-versa.

Upon comparison of BG with ISG, it was revealed that BG mixes succeeded to demonstrate superior performance. From the material optimization, rheological and mechanical performance study, it is recommended that BG with NMAS 16 mm can be used for conventional SCC.

The purpose of this paper is to provide a descriptive analysis of the carbon management activities of the cement industry in Europe, based on a study involving the four largest producers of cement in the world. Based on this analysis, the paper explores the relationship between managerial perception and strategy, with particular focus on the impact of government regulation and competitive dynamics.

The research is based on extensive documentary analysis and in‐depth interviews with senior managers from the four companies who have been responsible for and/or involved in the development of climate change strategies.

It was found that whilst the cement industry has embraced climate change and the need for action, there remains much scope for action in their carbon management activities, with current effort concentrating on hedging practices and win‐win efficiency programs. Managers perceive that inadequate and unfavourable regulatory structure is the key barrier against more action to achieve emission reduction within the industry. Interestingly, EU cement companies are also shifting their CO₂ emissions to less developed countries of the South.

The paper analyses corporate climate strategy in one of the most carbon intensive and yet least studied industries. With specific focus on the EU, the paper highlights a number of policy approaches for encouraging the cement industry on the path of deeper emission reduction.

No‐fines concrete (NFC) is an open textured cellular concrete obtained by eliminating either fines or sand from the normal concrete mix. Research in the 1950s showed this material to be capable of energy and cement savings and worthy of being seen as a material that would revolutionise the way affordable homes could be built. In today's context, it may be argued that homes built using this material suffer from fuel poverty as a result of their thermal performance characteristics. This paper seeks to discuss the performance characteristics of NFC in social housing by identifying the nature of the material and the influence of pore structure on heat loss through the fabric of the building.

Exploratory work was carried out to determine the build and performance characteristics of NFC as used in a range of social housing units. The work includes both laboratory tests and site investigations to identify the physical, thermal, visual and quality characteristics of NFC in cores taken from existing housing units in Irvine, Scotland and units cast in the lab.

The findings from the tests are used to discuss the actual characteristics of NFC and highlight the nature of pores in NFC and, their influence on heat loss through the external fabric.

Identifying the nature of pores in NFC helps provide approaches towards optimising solutions aimed at improving the thermal performance of the building.

This paper is the first to discuss the on‐site build and performance characteristics of NFC and the nature and influence of pores on the thermal performance of NFC.

Particles bed binding by selective cement activation (SCA) method is a computer-aided manufacturing (CAM) technique used to produce cementitious elements. A computer-aided design file is sliced to generate G-codes before printing. This paper aims to study the effect of key input parameters for slicer software on the final properties of printed products.

The one factor at a time (OFAT) methodology is used to investigate the impact of selected parameters on the final properties of printed specimens, and the causes for the variations in outcomes of each variable are discussed.

Finer aggregates can generate a more compact layer, resulting in a denser product with higher strength. Fluid pressure is directly determined by voxel rate (r_V); however, high pressures enable better fluid penetration control for fortified products; for extreme r_Vs, residual voids in the interfaces between successive layers and single-line primitives impair mechanical strength. It was understood that printhead movement along the orientation of the parts in the powder bed improved the mechanical properties.

The design of experiment (DOE) method assesses the influence of process parameters on various input printing variables at the same time. As the resources are limited, a fractional factorial plan is carried out on a subset of a full factorial design; hence, providing physical interpretation behind changes in each factor is difficult. OFAT aids in analyzing the effect of a change in one factor on output while all other parameters are kept constant. The results assist engineers in properly considering the influence of variable variations for future DOE designs.

Establishing toughness performance in concrete using steel fibres is well understood, and design guides are available to assist with this process. What is less readily understood is the use of Type 2 synthetic fibres to provide toughness. This problem is exacerbated by the wide range of synthetic fibres available, with each different fibre providing different structural properties. This paper seeks to address this issue.

The paper examines the relative pull‐out values of two single fibre types, i.e. steel and Type 2 synthetic fibres. The pull‐out test results have informed the doses of fibre additions to beams which have been used to equate near equal toughness performance for each fibre type.

The results show that synthetic Type 2 fibres, when used at a prescribed additional volume, can provide toughness equal to steel fibre concrete.

The scientific study of fibre pull‐out behaviour is well understood and described herein under additional reading. Practical testing to show contractors and clients how to balance the dose of fibres in concrete, so that synthetic fibres could be used as a steel fibre replacement, is not well researched. This paper bridges the information gap.