•Residual properties of rubberized concrete were investigated.•ANN models are proposed to predict the residual performance of rubberized concrete.•The ANN outputs show good agreement with ...experimental results.
Considering scarcity of natural sand, waste rubber tyre can be an alternate ingredient for replacement of conventional fine aggregates in the production of concrete. Use of the waste rubber tyre in building materials is beneficial from sustainable and economical points of view. A systematic and comprehensive experimental study was conducted earlier by the authors for the mechanical and durable properties of rubberised concrete subjected to elevated temperature. However, there is non-availability of a mathematical model for rapid prediction of mechanical properties of the rubberised concrete subjected to elevated temperature. To bridge this gap an attempt has been made for development of explicit expressions through artificial neural network (ANN) approach in this paper. The training, validation, and testing data sets for ANN, are compiled from the recent researches of the authors. The input data sets contain six levels of elevated temperature (T) with three exposure durations (t) for all the specimens having six different fiber content (RF) along with three different water-cement ratio (w/c). On the other hand, the output parameters consist of mechanical properties (compressive strength static modulus of elasticity, dynamic modulus of elasticity and mass loss). Sensitivity analysis has also been carried out to investigate the effect of the input parameters on the output parameters. It is found that the average contribution of w/c,RF,T,t to all the output parameter is 6.67%, 10.10%, 80.01% and 3.22% respectively. The parameter T has highest impact on the all output parameters followed by RF whereas, rest of the input parameters (w/c,t) have relatively lower impact.
•Valorization of sugarcane bagasse ash generated by the Brazilian sugarcane industry.•Sugarcane bagasse ash as a filler material in powder-type self-compacting concrete.•Mixture design method based ...on statistical factorial design approach.•Good mechanical and durability performance of tested self-compacting concretes.
The aim of the current study is to assess the feasibility of incorporating sugarcane bagasse ash (SBA) from the sugar and ethanol industry as a filler material in the production of self-compacting concrete (SCC). For this purpose, paste composition was designed in the first stage of this study by conducting an experimental plan at the mortar level. During the second stage, SCC mixture properties were evaluated by considering the paste mixture proportions defined in the first stage. The study at the mortar level was conducted based on a statistical factorial design approach, which offers a valid basis for developing empirical models that allow determination of optimal settings of the design variables to satisfy all performance requirements. At the concrete level, the impact of three optimised paste mixtures on SCC properties was assessed. Fresh state, mechanical, and durability properties were evaluated. Mortar and concrete test results revealed that SBA can be used successfully in powder-type SCC as a filler material, and it exhibits good self-compacting ability and strength levels, which are adequate for many current civil engineering applications.
Bu çalışmada, farklı tür agregalardan üretilen silindirle sıkıştırılmış beton (SSB) örneklerinin özellikleri araştırılmıştır. Bağlayıcı olarak CEM I 42,5 R Portland çimentosu, dolomit, bazalt, mermer ...ve iki farklı tür kalker olmak üzere beş farklı agrega, doğal kum ve şebeke suyu kullanılmıştır. Agrega örnekleri üzerinde sıkışık ve gevşek birim hacim ağırlık, özgül ağırlık, su emme, Los Angeles parçalanma direnci tayini ve elek analizi deneyleri yapılmıştır. Farklı tür agregalarla yapılan karışımlarda su/çimento oranı 0,35 olarak sabit tutulmuştur. Dolomit, bazalt, mermer, iki farklı tür kalker olmak üzere beş farklı agreganın her biri 12-19 mm kırmataş II, 4-12 mm kırmataş I ve 0-4 mm kırmataş tozu olarak kullanılmıştır. Ayrıca farklı agrega ile üretilen betonların her birinde 0-4 mm boyutunda doğal kum kullanılmıştır. 7 ve 28 günlük basınç dayanımlarının belirlenmesi için 15 cm çapında ve 30 cm yüksekliğinde silindir, 28 günlük eğilme dayanımı için ise 15 cm×15 cm×75 cm boyutlarında prizmatik kiriş örnekler üretilmiştir. Eğilme dayanımı testinden önce 28 günlük prizmatik kiriş numunelerden yararlanılarak ultrases geçiş hızı ve dinamik elastisite modülü değerleri belirlenmiştir.
In study, test results of roller compacted concrete (RCC) samples produced from different types of aggregates were researched. CEM I 42.5 R Portland cement, five different coarse aggregates (dolomite, basalt, marble, two different types of limestone), natural sand and tap water were used. The compact and loose bulk density, specific gravity, water absorption, Los Angeles abrasion resistance and sieve analysis tests were performed on the aggregate samples used. The water/cement ratio has been kept constant as 0.35 in mixtures produced with different types of aggregates. The RCC produced with five different aggregates: dolomite, basalt, marble and two different types of limestone, each were used as 12-19 mm crushed stone II, 4-12 mm crushed stone I and 0-4 mm crushed stone powder. In addition, 0-4 mm natural sand was used in each of the concretes produced with different aggregates. In order to determine the compressive strengths at the ages of 7 and 28 days, cylindrical specimens with 15 cm diameter and 30 cm height were used. Prismatic specimens with the dimensions of 15 cm×15 cm×75 cm were used to determine flexural strengths at the age of 28 days. Before bending test, ultrasonic pulse velocity and dynamic modulus of elasticity values were determined by using 28-day prismatic specimens.
Lightweight porous concrete is a popular energy-saving building material. However, the raw materials required to prepare this concrete paste are extracted from natural resources, and its early ...compressive strength is so low that it cannot be used for applications with a short casting time. In order to improve the early compressive strength and reduce energy and resource consumption during preparation, this study proposes using only solid wastes to prepare the pastes for lightweight porous concrete that can be ready to use in a short time. This was achieved by sintering a mixture of aluminum dust, flue-gas desulfurization gypsum, carbide slag, and red mud to obtain a cementitious material (CM). Then, other solid wastes (14.26 wt% flue-gas desulfurization gypsum, 9.9 wt% fly ash, and 1 wt% carbide slag) were blended with the CM to prepare ready-to-use lightweight porous concrete (RLPC), which was successfully prepared using only industrial solid wastes as the raw materials. The minimum thermal conductivity obtained was 0.15 W/m·K, and the maximum 28-d compressive strength obtained was 3.57 MPa for an RLPC dry density of ∼600 kg/m3. In addition, the 4-h and 1-d compressive strengths were up to 1.31 MPa and 1.57 MPa, respectively, which is even higher than the 28-d compressive strength of most conventional foamed concretes. Finally, our life cycle assessment showed that the preparation of RLPC has a lower environmental impact than that of conventional foamed concrete.
•An energy-saving method to prepare RLPC is presented.•The raw materials of the paste were gathered entirely from industrial solid waste.•The synergistic effects of various industrial solid wastes are discussed.•RLPC was proven to be environmentally friendly and energy-saving through LCA.
•The ER was applied to partially carbonated concrete as a prevent technique.•FTIR and TGA were used to evaluate the ER efficiency in concrete.•ER was more effective for OPC concretes compared to MK ...and SF-concretes.
The present study evaluates the efficiency of the application of electrochemical realkalisation (ER) as a prevent technique for partially carbonated blended reinforced concrete using two pozzolanic additions, metakaolin (MK) and silica fume (SF), replacing 10% cement. In this study, the concrete was exposed to controlled climate conditions (1% CO2, 65% RH, 25 °C) until 65% carbonation was reached (without initial pre-corrosion). Subsequently, ER was applied for a period of 7, 15 and 21 days for the concrete specimens without additions (OPC, reference material); in the case of blended concretes, a single period of 15 days was carried out. In all cases, sodium carbonate (Na2CO3) as an electrolyte and a current density of 1 A/m2 were used. The influence of the additions on the efficiency of ER was studied by the pH evaluation method, using an alcoholic solution of phenolphthalein at 1% as an indicator, and the test was performed before and after the ER process. As a complementary test, FTIR and TGA were used. Linear polarization resistance (LPR) and half-cell potential (Ecorr) were used to monitor the progress of the corrosive process. The results verified that this method increased the pH of the cement matrix; however, ER was more effective for OPC concretes compared to blended concretes. After the ER treatment, the corrosion levels tended to decrease over time; however, the values did not reach the initial pre-corrosion state before the application of ER.
This paper reviews the fundamentals of the durability of structural concrete, and then applies the concepts to the durability design, quality control, performance assessment and maintenance planning ...of concrete structures in Hong Kong-Zhuhai-Macau (HZM) sea link project with design working life of 120 years. The durability design adopts a multi-level philosophy for different durability risks and uses model-based approach to determine design parameters. The long-term exposure data of 30 years were used to calibrate the chloride ingress model and quantify the modelling uncertainty. The durability quality control was realized through converting the design values to laboratory characterization values, especially for the chloride diffusivity. With the data collected in construction phase, a full-probabilistic assessment is performed on the achieved performance against the chloride ingress, serving as basis for maintenance planning. The open issues related to the durability of concrete infrastructures with long service life are elaborated in the end.
•Ordinary Portland cement was replaced with 5–20% by weight of sugarcane bagasse ash.•Compressive strength, chloride penetration resistance and sorptivity tests were carried out.•15% substitution of ...treated sugarcane bagasse ash (TBA) exhibited a better durability property.•Treated sugarcane bagasse ash could be used in making the ultrahigh strength concrete (UHSC).
This paper discusses the feasibility of utilizing sugarcane bagasse ash as a pozzolanic material in the production of Ultra High Strength Concrete (UHSC). Ordinary Portland Cement was replaced with Treated Bagasse Ash (TBA) in this investigation. The replacement dosage varied from 5% to 20% by weight of cement. The effect of bagasse ash on workability, compressive strength, chloride penetration resistance and sorptivity was examined. In addition to this, the effect of different curing regimens on hardened properties of UHSC was carried out. The results proved that it is possible to produce UHSC with cylinder compressive strength more than 160 MPa by incorporating bagasse ash. Optimum replacement ratio of 15% yielded better performance in all the tests, without having any adverse effects on hardened concrete. Convincingly, 20% substitution of sugarcane bagasse ash is good enough for producing UHSC.
•pH-dependent leaching applicability for carbonated waste materials was explored.•Samples underwent accelerated carbonation and were leached with EPA Method 1313.•XRD was performed to identify ...differences in mineralogy between materials.•pH-dependent leaching tests were partially applicable for carbonated waste.•Implications for pH-dependent leaching efficacy were explored.
pH is a vital factor related to the heavy metal leaching from wastes. Over time, waste materials may be naturally weathered in the presence of water and carbon dioxide, reducing their pH and altering their mineralogy. Here we evaluate whether conducting a pH-dependent leaching test on wastes expected to carbonate sufficiently reflects the leaching of these wastes upon carbonation. Certain elements, such as Al and Sb, exhibited different leaching trends for carbonated and un-carbonated samples of two different waste materials. XRD results observed different mineral phases as a result of carbonation in incineration bottom ash. The application of pH-dependent leaching tests on fresh waste samples (at neutral pH values) were found to potentially mischaracterize leaching from carbonated waste samples at similar pH values for some elements and waste materials.
•Recycled asphalt pavement (RAP) materials are used in roller compacted concrete.•Increasing RAP in roller compacted concrete decreases its density.•Increasing RAP in roller compacted concrete ...increases its tensile strength.•50% max of RAP materials are recommended to be used in roller compacted concrete.
In some countries of the world, for economic and environmental reasons, recycled asphalt pavement (RAP) materials comes from old bituminous road pavements are increasingly investigated. In Algeria particularly, a huge quantity of this type of waste is produced every year but rarely quantified and rarely reused. This paper evaluate the effects of various RAP sizes as substitute of coarse and fine natural aggregate (NA) on the mechanical properties and durability of roller compacted concrete (RCC). The RAP and NA materials are characterized and compared. The mechanical properties and durability of RCC with RAP materials are analyzed and compared to the RCC with 100% of NA. The experimental results showed that it is possible to manufacture RCC with a maximum of 50% of RAP materials. In addition to that, it may be more environmentally efficient to valorise this type of waste in concrete, because this helps to remove in general some parts of wastes and protects the environment.
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