Matériaux et constructions
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Steel–concrete bond behaviour of lightweight concrete with expanded polystyrene (EPS)
Matériaux et constructions - Tập 48 - Trang 139-152 - 2013
The experimental program presented in this paper was aimed to investigate the steel–concrete bond behaviour of lightweight concrete. The lightweight concrete was obtained by substituting part of the traditional coarse aggregates with beads of expanded polystyrene (EPS). The addition of EPS in the concrete mix could influence the bond behaviour with steel reinforcing bars, albeit the same strength of a normal concrete is reached. After different mixtures of normal and lightweight concrete with EPS have been tested in order to check the influence of several parameters on the compressive strength, two mixtures of lightweight concrete with EPS and one of normal-weight concrete were finally prepared for carrying out the bond tests. A traditional pull-out scheme was assumed for the bond tests of black and zinc-coated steel bars embedded in concrete blocks made of the three mixtures.
Effect of physical, chemical and electro-kinetic properties of pumice on strength development of pumice blended cements
Matériaux et constructions - Tập 46 - Trang 1695-1706 - 2013
In the present study, the potential effects of physical, chemical and electro-kinetic properties of pumice on the strength development of pumice blended cements (PBC) were examined and documented. A significant relationship between zeta potential of pumice samples, setting time and water demand of PBC was found. A relationship between the chemical content of pumice samples and compressive strength of PBC was also observed. However, zeta potential of the pumice samples was found to be less effective in strength development. Despite the lower clinker content, the setting time of the PBC samples was shorter than control specimen. 30 % pumice replacement by clinker resulted in 5–28 % reduction in 28-day strength depending on the characteristics of the pumice samples and grinding time.
Combined aggregates: a computer-based method to fit a desired grading
Matériaux et constructions - Tập 17 - Trang 139-144 - 1984
A computer-based method to fit a desired grading by combining different aggregate fractions is presented. It provides “the best” approximation, since the solution minimizes the differences (squared) between the desired and the actual grading. The algorithm used is based on the modified Gram-Schmidt method with iterative refinement. The utility of the method increases with the number of fractions to be combined or when a gap-graded combination is desired. The method is both rapid and flexible, and permits different alternatives to be considered and hence to make technically and economically sound decisions. Examples of its application are presented.
Nghiên cứu tác động của đặc điểm hydrogel đến khả năng tự phục hồi của vật liệu xi măng Dịch bởi AI
Matériaux et constructions - Tập 56 - Trang 1-18 - 2023
Mặc dù đã có nhiều nghiên cứu về khả năng tự phục hồi của các vật liệu xi măng chứa hydrogel, nhưng mối liên hệ giữa khả năng tự phục hồi và các đặc tính của hydrogel vẫn chưa được khám phá đầy đủ và còn nhiều điều chưa hiểu rõ. Do đó, tính mới của bài báo này là khảo sát khả năng tự phục hồi của các vật liệu xi măng chứa nhiều loại hydrogel với các hành vi khác nhau. Phân tích nhiệt trọng lượng, phổ hồng ngoại biến đổi Fourier và kính hiển vi điện tử quét trang bị phổ huỳnh quang tia X phát xạ năng lượng đã được sử dụng để nghiên cứu các đặc điểm hóa học của sản phẩm phục hồi. Thử nghiệm uốn ba điểm và kính hiển vi quang học đã được sử dụng để đánh giá khả năng phục hồi sức mạnh cơ học và việc lấp đầy vết nứt tương ứng trong các vật liệu xi măng chứa hydrogel. Các sản phẩm phục hồi được chứng minh bao gồm canxi-silicate-hydrate (C–S–H), ettringite, canxi hydroxit và canxi carbonate. Bột mới được điều chỉnh hydrogel với khả năng hút nước cao nhất cho thấy hàm lượng canxi carbonate cao nhất. Tất cả các bột mới được điều chỉnh hydrogel đều thể hiện sự cải thiện trong khả năng phục hồi sức mạnh và việc lấp đầy vết nứt so với bột điều khiển, và sự cải thiện này rõ rệt hơn ở bột có khả năng hút nước cao nhất.
#hydrogel #khả năng tự phục hồi #vật liệu xi măng #sức mạnh cơ học #hóa học phục hồi
La 32e Réunion de la Commission Permanente de la RILEM
Matériaux et constructions - Tập 12 - Trang 151-154 - 1979
Complex modulus of cement-bitumen treated materials produced with different reclaimed asphalt gradations
Matériaux et constructions - Tập 55 - Trang 1-15 - 2022
The increasing attention over cold recycling technologies as sustainable paving solutions requires a proper characterisation in terms of complex modulus for supporting the pavement design. Among cold recycled materials, cement bitumen treated materials (CBTM) benefit from the presence of both bituminous and cementitious binders. This research aims at characterising the complex modulus of CBTM mixtures produced with three different gradations, modified bitumen emulsion and two types of cement. The complex modulus measurements were modelled considering the usual viscous dissipation behaviour, linked to the bituminous component of the mixtures, along with a time- and temperature-independent dissipation component. The results showed that both the aggregate skeleton and the composition of the fine aggregate matrix affected the rheological behaviour. Furthermore, the role played by the aged binder contained in the reclaimed asphalt aggregate was highlighted by the parameters of the rheological model.
Estimating shear properties of walnut wood: a combined experimental and theoretical approach
Matériaux et constructions - Tập 50 Số 6 - 2017
Fatigue testing and performance of steel reinforcement bars
Matériaux et constructions - Tập 17 - Trang 43-49 - 1984
The methods of testing and the fatigue performance of six types of high strength steel reinforcement have been studied. Effects of bar diameter and butt-welding have been evaluated with an emphasis on long endurances. There is no evidence of the commonly assumed endurance limit at around 2×106 cycles and fractures occurred at up to 97×106 cycles. The performance can be represented by the expression σ
r
9
N=K, where σr is stress range and N is cycles to failure. The value of K is dependent on type of test, bending or axial, and bar diameter. It is concluded that it is appropriate to design using the performance for axial testing in air. The method of expressing performance is uniform with classification of welded connections and gives a safe representation of behaviour.
Effects of elevated temperature exposure on heating characteristics, spalling, and residual properties of high performance concrete
Matériaux et constructions - Tập 34 Số 2 - Trang 83-91 - 2001
Long term properties under marine exposure of steel fibre reinforced concrete containing pfa
Matériaux et constructions - Tập 21 - Trang 352-358 - 1988
The paper presents results on the long-term mechanical properties and durability under marine exposure of a steel fibre reinforced concrete (SFRC) mix containing pulverized fuel ash (PFA) which was developed for marine applications. The mix was of proportions by weight of PFA:OPC:fine aggregate:coarse aggregate of 0.26:0.74:1.51:0.84 with a water/(OPC+PFA) ratio of 0.4. The resulting cement content of the mix was 435 kg m−3. Theconcrete was reinforced with low-carbon steel, corrosion-resistant (galvanized) or melt-extract (stainless) steel fibres. Prism specimens were cured in the tidal zone at Aberdeen beach, under wet-dry cycles of sea-water spray in the laboratory, in a water-tank in the laboratory and in the laboratory air. The specimens were cured for up to 1200 marine cycles of exposure (640 days) and were tested at regular intervals of age. The paper presents results on long-term compressive strength, flexural strength and energy absorption capacity as measured from the load-deflection curves. The state of corrosion of fibres is also described. The results indicate that fibres embedded within concrete remain free from corrosion under marine exposure. In the case of fibres exposed at the concrete surface during casting, extensive corrosion occurs in low-carbon steel fibres, isolated rust spots appear in corrosion-resistant fibres and no corrosion is evident in melt-extract fibres. This corrosion, however, remains a surface phenomenon and does not penetrate the concrete. The long-term mechanical properties indicate no deterioration due to possible corrosion. In general the compressive strength of concrete increases significantly with fibre reinforcement.Increases in flexural strength and post-cracking ductility due to fibre reinforcement are of the order normally expected of SFRC.
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