196,119 research outputs found
Gypsum-plasters mixed with polystyrene balls for building insulation: Experimental characterization and energy performance
No full textIn order to reduce the heat loss from envelopes and to ensure energy saving in building refurbishment, polystyrene balls are added to Moroccan natural gypsum plaster. A complete characterization of the mechanical, thermal, and acoustic properties of the samples is carried out, taking into account different contents and diameters of the polystyrene balls. Increasing balls size, flexural strength peak value occurred with a lower polystyrene percentage. Thermal properties were measured by means of Small Hot Box apparatus. The values of conductivity were 0.191 and 0.116 W/mK for 10% and 30% addition of the smallest polystyrene balls, respectively. The acoustic properties were measured by means of a Kundt’s Tube, in terms of absorption coefficient and sound insulation. The absorption coefficients were slightly higher than the ones of standard plasters. As concerning insulation properties, a worse performance was expected, due to the lower density of the samples with the balls, according to the Mass Low. Anyway the transmission loss values were up to 45 dB, with a reduction of only 2–3 dB with respect to the samples without balls, showing a good performance for the proposed composites. Finally, dynamic energy simulations for a case study showed that polystyrene plaster with smaller balls applied on the wall surfaces of a residential building involved benefits both for heating and cooling energy demand. A small thickness (3 cm) of insulating material could be a suitable solution in order to enhance the thermal and acoustic performance and to reduce environmental impact of the construction systems
Ultimate Capacity and deflection behaviour of BFRP prestressed SCC beam
No full textAn experimental program involving the testing of concrete beams prestressed with Basalt Fibre Reinforced (BFRP)
Bars. Ultimate capacities and deflections were measured and compared with theoretical estimates. Beams were manufactured and subjected to four-point loading tests. The experimental work considered the use of Self-compacting concrete (SCC) and how material properties of the concrete affected the behaviour of the beams under loading. Analysis was carried out using a design codes and first principles with comparisons made with experimental results, predominantly focusing on vertical deflections. The flexural test results and analytical predictions showed very good agreement in terms of deflection, cracking moment and ultimate moment
Structural Behaviour of SCC
No full textThe State-of-the-Art Report of RILEM Technical Committee 228-MPS on Mechanical properties of Self-Compacting Concrete (SCC) summarizes an extensive body of information related to mechanical properties and mechanical behaviour of SCC. Due attention is given to the fact that the composition of SCC varies significantly. A wide range of mechanical properties are considered, including compressive strength, stress-strain relationship, tensile and flexural strengths, modulus of elasticity, shear strength, effect of elevated temperature, such as fire spalling and residual properties after fire, in-situ properties, creep, shrinkage, bond properties, and structural behaviour. A chapter on fibre-reinforced SCC is included, as well as a chapter on specialty SCC, such as light-weight SCC, heavy-weight SCC, preplaced aggregate SCC, special fibre reinforced SCC, and underwater concrete
3D printing of fibre cement-based materials: fresh and rheological performances
No full textInternational audienceThe aim of this paper is to investigate the effect of different mix composition on fresh and rheological properties of a printable mortar. For the mix design, two binders such as fly ash (FA), and silica fume (SF) were used with cement and sand for a water/binder ratio of 0.50. Polypropylene fibres (PP), superplasticizer (SP), and viscosity modifying agents VMA (Diutan gun and nano-clay) were used in the investigation. The results show that adding 24% of fly ash and 8% Silica fume increased the yield stress, cohesiveness, and improved the structure homogeneity and stability which appeared to be an advantage to print layers. Indeed it reduced the fluidity, bleeding and the blockage of layers. Additionally, it also improved the passing ability through the extruder and showed a greater resistance to penetration. The addition polypropylene fibres (0.2% to 0.6%) led to a higher yield stress, and cohesiveness of the mix. This is led to a stable mortar and kept the shape of layer under its own weight and sustained weight of successive layers. The incorporation of PP fibres reduced the time gap. Furthermore, high dosage of fibres can create more difficulties to extrude layers and led more drainage phenomenon which increased the stiffening of the mix. PP fibres might be efficient to print layers due to their small length and diameter which resulted in a dense and efficient network. VMAs cause an important loss of workability and time gap which influenced the passing ability of the mix through the extruder. However a high dosage of SP increased also bleeding and segregation and may affect the stability and shape of the printable layers. Good correlations existed between slump flow results, penetration results and also yield stress
Structural Behaviour of a 10-m Pre-stressed Slab Made with Basalt Fibre Reinforced Polymer Bars (BFRP) and Fibre Reinforced Self-Compacting Concrete (FRSCC)
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Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Life Cycle Assessment of a Wall Made of Prefabricated Hempcrete Blocks
No full textHempcrete is a natural building material obtained mixing hemp shives (i.e., the woody core
of the hemp plant) with a lime-based binder and water. Hempcrete as construction material is gaining
increasing interest as the EU aims to achieve net zero emissions by 2050. This material has, in fact,
the ability to uptake carbon dioxide from air (i.e., via carbonation) and to store carbon for long time.
The goal of the present work is to deeper analyze the environmental profile of hempcrete, in order to
assess its potentials in reducing emissions of construction sector. Specifically, Life Cycle Assessment
(LCA) of a non-load-bearing wall made of hempcrete blocks is carried on. The analysis encompasses
the whole life cycle from the extraction of raw materials to the end of the service life. The analyzed
blocks are produced by an Italian company. Only aerial lime is used as binder, microorganisms are
added to the blocks to accelerate carbonation. The impact on climate change is assessed through the
GWP 100 method proposed by IPCC. Preliminary results reveal a nearly neutral carbon budget
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