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The objective of this research was to determine the impact of algal colonisation on natural stone masonry. Experimental work was carried out to determine the physical and chemical damage caused by micro-algae using reflected light microscopy, Scanning Electron Microscopy and Inductively Coupled Plasma - Atomic Emission Spectroscopy. Colonisation experiments were performed on individual mineral chips of quartz, calcite, dolomite, siderite, labradorite, orthoclase, a perthitic albite, muscovite and montmorillonite; as well as the Giffnock sandstone, a traditional building stone of the Glasgow area. Work was also carried out to determine the effect of algal colonisation on the absorption of water into a masonry surface. The research determined that algae create an alkaline environment in the areas they colonise. Algal mediated damage to the mineral substrates includes the dissolution and pitting of carbonate surfaces as well as the etching of plagioclase feldspar surfaces. Algal colonisation preferences were noted throughout the experiment with algae preferentially colonising kinks and steps in the topography of mineral surfaces as well as grain edges. Preferences were also seen in the colonisation of the Giffnock sandstone with micas showing heavy colonisation compared to other minerals in the lithology. Algal swelling and contraction cycles were examined in Environmental Scanning Electron Microscopy experiments and the impact that this physical swelling may have on the stone is modelled. Algal biofilms at the surface of the stone lead to an acceleration in the rate at which water enters the surface of the stone, this is important as water is the main weathering catalyst for masonry weathering. The findings of this project implicate algae in the weathering of natural stone masonry through enhanced mineral dissolution, mineral etching and pitting, patina formation, physical weathering through swelling cycles and the alteration of the surface physical properties in relation to water absorption.

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Stabilised-soil cement building blocks are an established building material in many areas of the Less Developed World. This thesis has been split into three parts. Part A presented an overview of the process of soil-stabilisation and outlined the roles which soil structure and curing play in stabilisation. It examined methods of testing soils, highlighting errors presented in the published literature and presenting corrected testing procedures and unified plans for their implementation. Part B examined the conventional quasi-static block compaction process (slowly applied pressure) and established that no cost-effective increase in the compacted block density can be achieved by altering such moulding configurations as mould-wall roughness, mould-wall taper, number of applied pressure cycles and double-sided pressure application. The tests were also used to assess the plausibility of several theoretical mechanisms underlying quasi -static compaction. Cement may be traded against compaction pressure for a given final cured strength. The relation of compaction pressure and cement content to well-cured strength was established for 50 mm diameter cylinders and used to assess the financial benefit of high-pressure compaction. It was shown that savings in the cost of cement associated with high-pressure compaction were outweighed by the additional cost of such machinery. However there were additional benefits found to high-density compaction, beyond the saving in stabiliser costs. It was established that a highdensity moulding machine in the range £1000 - £1500 would allow these benefits to become cost competitive. Part C examined both experimentally and theoretically an alternative dynamic (impact blow) compaction process, establishing that optimised dynamic compaction may produce strength equivalent to quasi-static high-density moulding while requiring only 25-50 % of the energy. Five theoretical models of the process were developed and the Combined Airlock/Friction/Compression Wave Model was shown to have the most explanatory power.

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Self-compacting concrete (SCC) can flow into place and compact under its own weight into a uniform void free mass even in areas of congested reinforcement. The research reported in this thesis examined the production of SCC with readily available UK materials, with the overall aims of evaluating test methods and establishing a suitable mix design procedure. There have been significant recent developments and applications of SCC in several countries, notably Japan. A literature survey gave an understanding of the advantages and properties of SCC, test methods and the range of constituent materials and their relative proportions for its successful production. A range of SCC mixes can be produced with the common features of a lower aggregate content than conventional concrete and the use of superplasticizers. Most mixes also contained one or more of pulverized fuel ash, ground granulated blast furnace slag and an inert powder filler. A four stage experimental programme was carried out: *tests on pastes to assess the effect of the types and proportions of the powders and superplasticizers on the rheology. *tests on mortars to determine suitable dosage of superplasticizers for high fluidity, low segregation and low loss of workability with time after mixing. Flow spread and funnel tests were used. *tests on fresh concrete to enable suitable types and quantities of coarse aggregate to be combined with these mortars to produce SCC. Fluidity and viscosity were measured using slump flow and V-funnel tests, and passing ability using L- and U-type tests. Two-point workability tests were also carried out, and a novel way of assessing segregation resistance was developed. *tests on hardened concrete to determine compressive strength, bond to reinforcement and drying shrinkage. A mix design procedure, based on a method suggested by Japanese workers, has been developed. This includes optimisation of the mix with a linear optimisation tool from a commercial spreadsheet package.

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