The work in this thesis examines the suitability of utilising ground waste brick as a cement replacement material. The brick types investigated were obtained from the UK,Denmark, Lithuania and Poland. Cement was partially replaced by various quantities and types of ground brick in mortar and concrete. Compressive strength, pore size distribution and sorptivity of mortar generally all benefit from the presence of ground brick and the greatest effect can be seen after water curing for one year. Compressive strength of concrete is also shown to increase as the fineness of ground brick increases although the optimum particle size for ground brick in concrete is still to be determined. The ground bricks investigated have a significant effect on the performance of ground brick mortar when exposed to sodium sulphate solution and synthetic seawater. It is seen that depending on the chemical and phase composition, the effect of ground brick can increase substantially the rate of deterioration of mortar or can reduce significantly the expansion observed. No definite mechanism was identified as being responsible for the observed deterioration of mortar exposed to sodium sulphate solution although it seems likely that water intake due to ettringite formation and adsorption of water by the resultant colloidal product are the primary causes of expansion. Sulphate content, glass content and oxide chemistry of brick are key factors as to its performance when used as a cement replacement material in mortar. Bricks with a high proportion of low calcium glass make very effective pozzolans. Bricks with high calcium glass or a low proportion of glass should not be used as pozzolans. Small amounts of sulphate in ground brick do not have any serious deleterious effects on ground brick mortars and can be beneficial. It is established that it is technically feasible to partially replace cement with ground brick in mortar and concrete, depending on its chemical and phase composition to produce a more durable, cost effective and (due to the lower cement content) a less environmentally damaging material than that produced without cement replacement.

The NIST miniature paste prism test was developed to assess sulphate resistance of cements faster than the commonly used ASTM C 1012 test. The goal of this research is to address the current limitations regarding the NIST procedure to determine the optimum testing parameters and to establish appropriate expansion limits. A range of variables including details of specimen design, curing regime, water-to-cementitious materials ratio, and prism length were tested on the materials with a wide range of sulphate performance. The findings of the study demonstrate that even though it can yield results in only three months, the NIST test can provide an erroneous differentiation between certain cementitious materials. Reliability and repeatability of the test results can be improved by using longer specimens and longer curing times. The NIST test can be used as a preliminary screening test, but users need to be aware of its limitations.

The NIST miniature paste prism test was developed to assess sulphate resistance of cements faster than the commonly used ASTM C 1012 test. The goal of this research is to address the current limitations regarding the NIST procedure to determine the optimum testing parameters and to establish appropriate expansion limits. A range of variables including details of specimen design, curing regime, water-to-cementitious materials ratio, and prism length were tested on the materials with a wide range of sulphate performance. The findings of the study demonstrate that even though it can yield results in only three months, the NIST test can provide an erroneous differentiation between certain cementitious materials. Reliability and repeatability of the test results can be improved by using longer specimens and longer curing times. The NIST test can be used as a preliminary screening test, but users need to be aware of its limitations.

This study describes the strength, toughness and strain-rate sensitivity of fibre-reinforced cement-based foams subjected to variable loading rates. Drop-weight impact tests were conducted on beams with cast density between 475 - 1200 kg/cu.m. The study shows that under quasi-static loading, the compressive strength, elastic modulus and the modulus of rupture of plain mixes scale with the square of the relative density. On the other hand, the flexural toughness factor scaled linearly with it. Fibres were seen to increase the flexural strength at all rates of loading, regardless of cast density. Further, cement based foams were seen to be strain-rate sensitive. The resistance of cement-based foams to sulphate exposure was also investigated. Heavier cement-based foams are more susceptible to sulphate attack and perform poorly with an increase in the duration of exposure when compared to the lightest mix which showed improved responses up to 30 days of exposure due to self-healing. / Structural Engineering

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