Effects of mineral and superplasticizer admixtures on the mechanical behaviour of lightweight concrete

This paper presents an experimental investigation of the combined effect of a superplasticiser admixture and metakaolin material on the mechanical behaviour of expanded clay lightweight concrete containing recycled glass aggregate. The optimum dosage of the superplasticiser admixture (type SNF) was adjusted and used by weight of cement. The short- and long-term mechanical properties of concrete mixes were measured in accordance with the relevant British/EN standards. The results obtained were compared with the results of control concrete mixes (without superplasticiser). They showed that the superplasticiser admixture exhibited a 20% reduction in mixing water content. All measured values of unit weight, compressive and splitting tensile strengths increased when the superplasticiser admixture and metakaolin material were used. The concrete mix containing 30% recycled glass revealed an increase in the mechanical strength compared with the mix of 15% recycled glass. However, the workability of the superplasticiser concrete mixes was degraded, reaching 44% reduction in slump value. </jats:p

Effect of Chases with Renovation Techniques on the Load Carrying Capacity of Masonry Walls

From MDPI via Jisc Publications RouterHistory: accepted 2021-11-03, pub-electronic 2021-11-09Publication status: PublishedInfrastructure through the masonry walls (for example, wiring and piping works) are usually installed using chases in different directions. Introducing these chases in a newly built wall will affect its overall load carrying capacity. However, there has thus far been very limited research into the effects of chases on the response and load carrying capacity of walls. This study has been undertaken to evaluate the structural behaviour of new masonry walls having chases in both horizontal and vertical directions and subjected to compression load throughout an extensive experimental programme. In addition, two renovation techniques have been proposed to infill the chases created in small scale walls (wallettes). The first technique involved the use of plastic wire mesh and cement mortar, while the second incorporated using galvanized steel channel together with the plastic wire mesh and cement mortar. Furthermore, a reference case of wallette without chases has been considered to enable reasonable comparisons to check the effect of the chases and the efficiency of the proposed renovation techniques. The outcomes of this study were used to modify the design equations proposed in the relevant codes of practice. The obtained results showed a notable reduction in the load carrying capacity of the masonry wall due to the introduction of the chases with a reduction percentage of 29% compared to the masonry wall without chase. The percentage decrease depends on the depth of the chase and the inclination angle of the load flow. The walls with horizontal chases exhibited more reduction in the load carrying capacity compared to those with vertical chases. The adopted renovation techniques using galvanized steel channel and/or plastic wire mesh with cement mortar recovered 55% and 93% of the lost load carrying capacity due to the presence of the chase and the failure was due to the de-bonded phenomena of the infill materials. Suitable factors of safety have been proposed to be incorporated in the compressive strength and modulus of elasticity formulas of the masonry walls of the BS EN codes

Effect of Chases with Renovation Techniques on the Load Carrying Capacity of Masonry Walls

Infrastructure through the masonry walls (for example, wiring and piping works) are usually installed using chases in different directions. Introducing these chases in a newly built wall will affect its overall load carrying capacity. However, there has thus far been very limited research into the effects of chases on the response and load carrying capacity of walls. This study has been undertaken to evaluate the structural behaviour of new masonry walls having chases in both horizontal and vertical directions and subjected to compression load throughout an extensive experimental programme. In addition, two renovation techniques have been proposed to infill the chases created in small scale walls (wallettes). The first technique involved the use of plastic wire mesh and cement mortar, while the second incorporated using galvanized steel channel together with the plastic wire mesh and cement mortar. Furthermore, a reference case of wallette without chases has been considered to enable reasonable comparisons to check the effect of the chases and the efficiency of the proposed renovation techniques. The outcomes of this study were used to modify the design equations proposed in the relevant codes of practice. The obtained results showed a notable reduction in the load carrying capacity of the masonry wall due to the introduction of the chases with a reduction percentage of 29% compared to the masonry wall without chase. The percentage decrease depends on the depth of the chase and the inclination angle of the load flow. The walls with horizontal chases exhibited more reduction in the load carrying capacity compared to those with vertical chases. The adopted renovation techniques using galvanized steel channel and/or plastic wire mesh with cement mortar recovered 55% and 93% of the lost load carrying capacity due to the presence of the chase and the failure was due to the de-bonded phenomena of the infill materials. Suitable factors of safety have been proposed to be incorporated in the compressive strength and modulus of elasticity formulas of the masonry walls of the BS EN codes