H. M. L. Schuur

The suitability of crushed building and demolition waste as a raw material for the production of calcium silicate products has been determined. Therefore calcium silicate bricks have been produced by replacing natural sand with crushed building and demolition waste of different sources. The mechanical properties of the bricks made with these wastes are comparable or in some cases even better than those of bricks with natural sand. In particular the green shear strength of the bricks is higher. The amount of quartz and reactive SiO₂ in the waste materials is high enough for the formation of tobermorite and hydrogarnet as cementitious materials between the grains. A negative aspect is the appearance of brown stains on the surface of the bricks when the waste materials are slightly contaminated with organic substances. This risk can be reduced by including a washing process, in addition to crushing of the waste.

Predicting strength properties of fine cementless fly ash – furnace bottom ash concrete

N. V. Vegerova

Methods for predicting strength properties of cementless ash – slag concrete for the long term have been developed at the Siberian State University of Industry. Data from a 10 – year study of an ordinary heavy concrete as compared with a cement concrete containing ash from thermal power plants were taken for analogies. The methods were as follows:

1. predicting based on the dynamics of the analog of the object for prediction using the method of similarity,
2. predicting based on the dynamics of the object indices in the "accelerated" time scale.

Development of utilization technologies for Mt Pinatubo ejecta as prime material for concrete: Part 1 – Concrete material structure-property characterization

G. Shimizu, P.A. Jorillo Jr., H. Adachi, B.A. Lejano, R.O. Baarde, M. Nakanishi

A total of 11 billion cubic meters of volcanic materials was ejected by the Mt. Pinatubo after its 13 major blasts from 1991 to 1994. This is considered as one of the most devastating disaster of the decade. The deposits are predominantly pumiceous of andesite scoria, with phenocryst-rich and phenocryst-poor dacite pumice fragments. Due to the large volume of volcanic debris, government and private institutions are looking for ways to utilize and maximize the economic potential of these materials. A medium term R&D Program was developed in order to come-up with utilization technologies of Pinatubo ejecta for the construction sector, and that will tackle basic questions of raw material sourcing, material optimization, design and tests of product for specific applications, validation, and transfer of technology to adoptee. The Technological University of the Philippines in cooperation with Nihon University, Japan’s Ministry of Education, and Philippines’ Department of Science and Technology launched an R&D program on utilization of Mt. Pinatubo ejecta for construction. The objective of this research program is to provide a comprehensive experimental and analytical characterization of Pinatubo ejecta material for various applications in the construction. This paper describes the significant results of extensive studies conducted by the authors in 1991- up to present in the following areas:

1. Structure-Property characterization of ejecta material
2. Application as prime material replacement for cement for durability improvement
3. Application for lightweight concrete and mix designs proportions

P.A. Jorillo Jr., B.A. Lejano, H. Adachi, G. Shimizu, R.O. Baarde, M. Nakanishi,

H. Tsuboyama

The Technological University of the Philippines in cooperation with Nihon University, and Japan’s Ministry of Education, launched an R&D project on utilization of Mt. Pinatubo ejecta for modular housing construction. One of the major concerns of the Philippine government is how to provide decent and affordable housing units to the Filipino masses. A possible answer to this is to come up with pre-cast and modular structural components that will facilitate speedy and low-cost construction of residential buildings. Another aspect of this study is the utilization of volcanic aggregates from the 1991 Mt. Pinatubo eruption. The utilization of this abundant material will address both the ecological problem and the challenge to create cheaper but quality construction materials.

New technology approach to age-old waste material (natural fibers) for composites

P.A. Jorillo Jr., G. Shimizu, T. Suzuki

Natural fibers like sisal, hemp, and coir fibers are abundant in many developing countries. Fiber composite cladding panels, prefabricated elements, special tiles and panels are few of the many possible applications of natural fiber cement composites. Socio-economic opportunities involved in the utilization of natural fibers include (1) elimination of solid waste, (2) environment friendly method of disposal, and (3) provision of a viable source of raw material. An R&D project was developed in collaboration with Nihon University, Shimizu Corporation-Institute of Technology, and the Technological University of the Philippines on centrifuged method of casting approach on natural fibers composites for pre-fabricated construction. The study tackled material optimization, and design and test of pre-cast elements using this technique. The paper describes the significant results of the project in the following areas

1. Applications of natural fiber reinforcement in gypsum-based lightweight panel
2. Applications in centrifuged method of casting for pipes and thin walled box sections
3. Application of centrifuged methods for production of gypsum based panels
4. Durability characterization of the natural fiber composites

1. Structure-Property characterization of ejecta material
2. Application as prime material replacement for cement for durability improvement
3. Application for lightweight concrete and mix designs proportions

C.F. Bonney, V.P. Fenton, R.J. Clark, W.L. Barrett, A.P. Ziogas, D. Harrison,

M. Grossou-Valta

This paper will present information on an industrial research project which aims to develop low cost ‘by-product’ fillers as a replacement for high cost ‘primary’ fillers. The source of the ‘by-product’ fillers will be fine waste residues from crushed rock aggregate quarries, which will be upgraded by particle size-reduction and by the application of suitable low cost beneficiation techniques. The products under investigation are industrial paints, membranes, low-grade paper, asphalt and lightweight concrete blocks. The paper will give details of the properties of two types of waste under investigation (siliceous and calcareous) as well as some details on the beneficiation studies.

Steel Fibers Made from Steel Cans in Concrete Engineering

A. Keyvani, N. Saeki

Recycling steel cans instead of making new products uses so much less energy, pollution, water and water pollution. In Japan in 1994 about 472,000 tons of steel cans could not be recycled. It meant a huge amount of steel plates could be reused as steel fibers to reinforce plain concrete by considering many advantages of fibrous concrete. Reusing of waste steel cans as a construction material in plain concrete can improve concrete properties and also protect corrosion of reinforced concrete. In this matter behaviour of steel fibers made from steel cans in a transparent gel and concrete specimens were studied. Results of experiments showed that such fibers with average thickness of 0.25 mm increase flexural strength of plain concrete about 150%. Durability of these fibers under an accelerated and artificial aggressive environment showed that more than 75% of fibers in the concrete matrix were sound. However, such fibers in contact with steel bars could cathodically protect corrosion of steel bars.

Carbonation and leaching of Portland cement with various blending materials

S. Mileti?, M. Ili?, Ž. Copkov, R. Munitlak

Degradation of Portland cement concrete, as well as the related protection and ensuring of Portland cement concrete structures against aggressive impacts by chemical agents, regardless whether this concerns liquid, gas or even solid phase under certain conditions, represents a complex problem of utmost importance for the economy in general, and especially for building construction and the construction industry. CaO leaching from Portland cement concrete in soft waters is one of the usual ways of Portland cement concrete degradation. Durability of steel in reinforced concrete is dependent mainly on the concrete protection layer. Usually, this layer has to be at least 4 cm. Also, pH value of this layer has to be higher than 7.5 to ensure alkaline media. But, CO₂ and moisture (acid rains recently) from the air makes this layer permeable to chlorine ions, such enabling steel corrosion. This effect is called concrete carbonation and is dependent of various factors, but mainly on the cement composition, w/c ratio and the concrete density. This paper presents results of CaO leaching content from Portland cements with various blending materials such as natural pozzolana and quartz river sand together with other characteristics of mentioned materials. Presented paper study also the changes produced by the carbonation when Portland cement, Portland fly ash cement and Portland blast furnace slag cement with various w/c ratios are exposed to the action of the atmosphere. The resistance to carbonation is significantly reduced when replacement of Portland cement by fly ash is higher than 15% and with higher w/c ratios.

Solidification of lead ions in Portland cement matrix

M. Ili?, S. Mileti?, D. Mili?, I. Br?eski

Solidification/stabilization is world-wide accepted treatment for immobilization of wastes such as heavy metals and represents mixing of materials with binders and reagents in order to reduce the leaching of contaminants. The most commonly used medium in solidification/stabilization process is Portland cement, pozzolana such as fly ash from coal and solvent silicates. The purpose of this paper is to investigate the use of pure Portland cement and Portland cement with addition of 30% fly ash as binders for immobilization Pb²⁺ ions. Samples (1x1x6 cm) were prepared by mixing cement with water containing 10 000 mg/dm³ Pb²⁺ and 30 000 mg/dm³ Pb²⁺. These samples were immersed in an aggressive acid solution (pH=4) and deionized water as reference. The temperature of acid solution and deionized water was 20° C and 50° C. Flexural strength of samples was measured. After 1, 3, 7, 14, 28, 35, 42, 49 and 56 days the concentration of toxic metal ions and Ca²⁺ ions in leachate solutions was determined by atomic absorption spectrometry. The end product of treatment, usually after sufficient curing, is solid monolithic material which, depending on characteristics of leaching, can be usefully applied or disposed of in a safe way.

Recycling and up-grading utility arisings and quarry wastes for highway construction and maintenance

N. Ghazireh, H.L. Robinson

The principles of sustainable development require the minimisation of the production of waste, the efficient use of materials and the recycling of wastes. The UK government is committed to pursuing opportunities for the promotion of reuse and recycling of waste materials where they can substitute for primary minerals. The Minerals Planning Guidance Note ( MPG6 ) published in 1994 proposed that an increasing contribution to aggregate needs should come from alternative sources, which include secondary materials, industrial by-products and wastes.

To address this theme, a consortium of Industrial partners, utility companies, private consultants, BRE , Manchester University and The DETR have combined their resources to develop novel technologies to enable cohesive, clay like materials to be recycled into useable aggregates for a range of applications.

The technology gained as a result of this research will enable the potential utilisation of millions of tonnes of utility trench arisings and quarry wastes generated each year. Key to the research is the use of industrial by-products as secondary slow cementing hydraulic binders, which will enable marginal materials and wastes to be treated and up-graded for uses where currently primary aggregates are used.