Empirical investigation to explore potential gains from the amalgamation of Phase Changing Materials (PCMs) and wood shavings

The reduction of gained heat, heat peak shifting and the mitigation of air temperature fluctuations are some desirable properties that are sought after in any thermal insulation system. It cannot be overstated that these factors, in addition to others, govern the performance of such systems thus their effect on indoor ambient conditions. The effect of such systems extends also to Heating, Ventilation and Air-conditioning (HVAC) systems that are set up to operate optimally in certain conditions. Where literature shows that PCMs and natural materials such as wood-shavings can provide efficient passive insulation for buildings, it is evident that such approaches utilise methods that are of a degree of intricacy which requires specialist knowledge and complex techniques, such as micro-encapsulation for instance. With technical and economic aspects in mind, an amalgam of PCM and wood-shavings has been created for the purpose of being utilised as a feasible thermal insulation. The amalgamation was performed in the simplest of methods, through submerging the wood shavings in PCM. An experimental procedure was devised to test the thermal performance of the amalgam and compare this to the performance of the same un-amalgamated materials. Comparative analysis revealed that no significant thermal gains would be expected from such amalgamation. However, significant reduction in the total weight of the insulation system would be achieved that, in this case, shown to be up to 20.94%. Thus, further reducing possible strains on structural elements due to the application of insulation on buildings. This can be especially beneficial in vernacular architectural approaches where considerably large amounts and thicknesses of insulations are used. In addition, cost reduction could be attained as wood shavings are significantly cheaper compared to the cost of PCMs

Behavior of FRP-confined normal- and high-strength concrete under cyclic axial compression

An important application of fiber-reinforced polymer (FRP) composites is as a confining material for concrete, both in the seismic retrofit of existing reinforced concrete columns and in the construction of concrete-filled FRP tubes as earthquake-resistant columns in new construction. The reliable design of these structural members against earthquake-induced forces necessitates a clear understanding of the stress-strain behavior of FRP-confined concrete under load cycles. This paper presents the results of an experimental study on the behavior of FRP-confined normal- and high-strength concrete under axial compression. A total of 24 aramid and carbon FRP-confined concrete cylinders with different concrete strengths and FRP jacket thicknesses were tested under monotonic and cyclic loading. Examination of the test results has led to a number of significant conclusions in regards to both the trend and ultimate condition of the axial stress-strain behavior of FRP-confined concrete. These results are presented, and a discussion is provided on the influence of the main test parameters in the observed behaviors. The results are also compared with two existing cyclic axial stress-strain models for FRP-confined concrete. © 2012 American Society of Civil Engineers.Togay Ozbakkaloglu and Emre Aki

Investigation of fibre reinforced mud brick as a building material

Most of the buildings in the rural areas are made out of limestone, low quality traditional concrete brick and adobe. But these materials do not have sufficiently high compressive strengths. In the present research, an earthquake-resistant material with high compressive strength has been sought. To this end, the mechanical properties of certain combinations of fibrous waste materials and some stabilisers were investigated thoroughly and some concrete conclusions were drawn. It was concluded that the interface layers of fibrous materials increased the compressive strength and a certain geometrical shape of these layer materials gave the best results. The mix proposed satisfies the minimum compressive strength requirements of ASTM and Turkish Standards. © 2004 Elsevier Ltd. All rights reserved

Durability of concrete made with granite and marble as recycle aggregates

The ornamental stone industries in Turkey produce vast amount of by-product rock waste (marble, granite) that could be used in concrete production suitable for construction purposes. In this work we have highlighted some technical aspects concerning the use of these waste materials. Durability of concrete made with granite and marble as coarse aggregates was studied. River sand and ground blast furnace slag (GBFS) were used as fine aggregates. The results were compared with those of conventional concretes. Slump, air content, slump loss and setting time of the fresh concrete were determined. Furthermore, the compressive strength, flexural- and splitting-tensile strengths, Young's modulus of elasticity, resistance to abrasion, chloride penetration and sulphate resistance were also determined. Control mortars were prepared with crushed limestone as coarse aggregates. The influence of coarse and fine aggregates on the strength of the concrete was evaluated. Durability of the concrete made with marble and GBFS was found to be superior to the control concrete. In the specimens containing marble, granite and GBFS there was a much better bonding between the additives and the cement. Furthermore, it might be claimed that marble, granite and GBFS replacement provided a good condensed matrix. These results illustrate the prospects of using these waste by-products in the concrete production. © 2008 Elsevier B.V. All rights reserved

Mineralogy of plain Portland and blended cement pastes

The compressive strength and microstructure of blended cement was investigated in this study. The hydration products of cements were identified by means of scanning electron microscopy (SEM) and polarising microscopy (thin section). Results indicated that the blended cement required pozzolanic activity in addition to its cementing property with the addition of 30% material. Aggregations of belite grains were observed which were surrounded by alite. Blended cement exhibited high early-term strength. However, its 3d-age strength is lower than ordinary Portland cement. On the other hand, all blended cement mortars fulfil the compressive strength requirements of TS 24. Hence, it can be said that blended cement can achieve adequate early compressive strength. A reduction in the amount of CSH gel and the porosity of the matrix in mortars were found to be responsible for the poor compressive strength of the cement paste in early the age. © 2007 Elsevier Ltd. All rights reserved

Durability of concrete made with granite and marble as recycle aggregates

The ornamental stone industries in Turkey produce vast amount of by-product rock waste (marble, granite) that could be used in concrete production suitable for construction purposes. In this work we have highlighted some technical aspects concerning the use of these waste materials. Durability of concrete made with granite and marble as coarse aggregates was studied. River sand and ground blast furnace slag (GBFS) were used as fine aggregates. The results were compared with those of conventional concretes. Slump, air content, slump loss and setting time of the fresh concrete were determined. Furthermore, the compressive strength, flexural- and splitting-tensile strengths, Young's modulus of elasticity, resistance to abrasion, chloride penetration and sulphate resistance were also determined. Control mortars were prepared with crushed limestone as coarse aggregates. The influence of coarse and fine aggregates on the strength of the concrete was evaluated. Durability of the concrete made with marble and GBFS was found to be superior to the control concrete. In the specimens containing marble, granite and GBFS there was a much better bonding between the additives and the cement. Furthermore, it might be claimed that marble, granite and GBFS replacement provided a good condensed matrix. These results illustrate the prospects of using these waste by-products in the concrete production. © 2008 Elsevier B.V. All rights reserved