The impact of colloidal nanosilica on concrete performance: compressive strength, ductility, and microstructural analysis

The impact of colloidal nanosilica on concrete performance: compressive strength, ductility, and microstructural analysis

In recent years, many studies have been done on the performance of concrete containing glass powder (GP). For the purpose of widespread use of GP in concrete mixes, a knowledge of the performance of such a mixture after a fire is essential for the perspective of structural use. This research work was carried out to evaluate the performance of High Performance Concrete (HPC) made with GP after being exposed to elevated temperature. The studied mixtures include partial replacement of cement by GP with up to 30%. The mechanical performance and structural alterations were assessed after high temperature treatment from 200oC to 800oC. The mechanical performance was evaluated by testing the specimens to the compressive and tensile strength. In addition, the mass loss and the porosity were measured to notice the structural alterations. Changes in microstructure due to temperature was also investigated by the X-ray diffraction (XRD) and thermal gravimetric analyses (TGA) as well as porosity adsorption tests. The results of the concrete strength tests showed a slight difference in compressive strength and the same tensile strength performance when replacing a part of the cement by GP. However, after high temperature exposition, concrete with GP showed better performance than the reference concrete for temperature below 600oC. But, after heating at 800oC, the strength of the concrete with GP drop slightly more than reference concrete. This is accompanied by an important increase in mass loss and water porosity. After the microstructure analysis, no important changes happened differently for concrete with GP at high temperature except a new calcium silica form appears after the 800

Using fine recycled concrete aggregate (FRCA) is challenging because of the presence of mortar fines in higher quantities. Past studies have reported a few approaches (Presoaking FRCA, surface treatment of FRCA, use of mineral admixture, method of mix proportioning, and mixing FRCA concrete) to improve the performance of FRCA concrete. However, these studies recommend the deployment of 30–50% FRCA as a substitute for natural fine aggregate. Additionally, the treatment methods are not cost-effective. To address these limitations and upscale the use of FRCA, this study introduces the particle packing method (PPM) for mix proportioning, a modified presoaking method for concrete mixing, and presents the effect of aggregate saturation level and paste content on the performance of concrete. Concrete mixes with 0–100% FRCA, 15% and 20% extra paste contents, and different aggregate saturation levels (50–100%) were prepared. The mechanical and durability properties of concrete, such as compressive strength, flexural strength, modulus of elasticity, abrasion resistance, sorptivity, water permeability, and chloride ingress, were analysed by replacing 0–100% crushed stone sand (CSS) with FRCA. The initial results showed a significant reduction in the mechanical and durability properties of fully saturated 100% FRCA concrete than the control mix. However, substantial improvement was seen by using partially saturated (50%) FRCA, and 20% paste content. The effect of decreasing FRCA saturation level was prominent. On using 50% saturated FRCA, the compressive strength, flexural strength, static and dynamic modulus of elasticity, and abrasion resistance, improved by 16%, 14%, 14%, 8%, 13%; and exhibited a lower sorptivity, water permeability, and chloride ingress of 56%, 14%, and 34%, respectively. The microstructural analysis showed that by reducing the saturation level and increasing the paste content a denser interfacial transition zone can be obtained. Furthermore, using PPM for mix proportioning is beneficial in minimizing the cement content for FRCA concrete mixes. The study demonstrates the synergistic effect of the PPM mix proportioning method, modified mixing method, 20% extra paste content, and partially (50%) saturated FRCA in improving the performance of untreated high-volume FRCA concrete, thereby supporting a sustainable approach.

Waterproof and impermeable problems seriously affect the safe use, normal structure, and working life of concrete projects. The waterproof performance of concrete can be improved by mixing with a proper amount of waterproofing agent; nevertheless, the early strength of concrete will be seriously affected. With the development of complex structures such as larg e spans in soil and water engineering and the increasingly complex engineering environment, people have put forward higher requirements for the working performance, strength, impermeability, durability, and intelligence of cement‐based materials required. This article compares the changes in compressive strength, fluidity, and water permeability of mixed concrete by controlling the two variables of waterproofing agent and nanosilica. Combining the results of XRD microstructure analysis, the influence of nanosilica and waterproofing agent on the performance of concrete is explored. Moreover, it is hoped that other excellent properties of concrete can be improved, and a waterproof material with good opacity can be found. The test results show that after adding waterproofing agent alone, the 3 d compressive strength of concrete is decreased by 14.81%, the water permeability is reduced by 71.6%, and the depth of carbonic acid molecules at 28 d is also decreased by 37.3%. On the other hand, compared with concrete using waterproof coating alone, after adding in nanosilica, the 3 d compressive strength is increased by about 30%, and the water immersion height is decreased. The results show that the addition of polymer has a great influence on the compressive strength and carbonic acid resistance of concrete.

Performance of high strength concrete containing recycled rubber

Effect of silica fume inclusion on the strength, shrinkage and durability characteristics of natural pozzolan-based cement concrete

Alkali Silica Reaction (ASR) is a chemical reaction that negatively affects concrete pavements strengths and integrity. ASR impedes concrete pavements' performance due to the formation of cracks and ultimate deformation if not properly controlled. Concrete pavements are gaining more relevance due to their ability to be constructed on soils with low bearing capacity and support high traffic loadings, thus increasing the need for studies on how ASR in the concrete pavements can be mitigated. This study employed compressive and flexural strength tests to determine the strength properties and deformation of concrete pavements due to ASR when partially replaced with CBA at varying percentages. Static structural modelling of the concrete as a multiphase material in which aggregates, cracks and gel formations are considered as embedded inclusions in the cement paste is then carried out. The results are then compared with relevant standards and findings of other researchers. The study's findings reveal that all the concrete cube samples passed the recommended compressive strength for rigid pavement, which range from 35 - 40 N/mm2 at 28th day. The concrete cube samples also passed the target strength of 48.25 N/mm2 obtained from the mix design. The effect of ASR resulted in lower compressive and flexural strengths observed at 180th and 240th days with lower CBA addition, while samples containing higher CBA contents had increasing compressive strength. The static structural modelling results reveal that the maximum deformation was obtained for the concrete cubes admixed with 0% CBA with 47.045 mm while the least deformation was obtained at 30% CBA replacement with deformation value of 5.542 mm on application of a 900 KN force. Therefore, the study posits that CBA addition will help reduce Portland Cement Concrete Pavement deformation due to ASR in relation to traffic loadings. Cite as: Adanikin A, Falade F, Olutaiwo A. Strength analysis of concrete pavement deformation due to Alkali Silica Reaction (ASR). Alg. J. Eng. Tech. 2020; 3: 020-027. http://dx.doi.org/10.5281/zenodo.4400227 References Hajighasemali S, Ramezanianpour A, Kashefizadeh M. The effect of alkali–silica reaction on strength and ductility analyses of RC beams. Magazine of concrete research. 2014;66(15):751-760. Grimal E, Sellier A, Multon S, Le Pape Y, Bourdarot E. Concrete modelling for expertise of structures affected by alkali aggregate reaction. Cement and Concrete Research. 2010 ;40(4):502-507. Monette LJ, Gardner NJ, Grattan-Bellew PE. Residual strength of reinforced concrete beams damaged by alkali-silica reaction—Examination of damage rating index method. Materials Journal. 2002 ;99(1):42-50. Huaquan YA, Zhen LI, Meijuan RA, Xiaomei SH. Study on Influence of Aggregate Combination and Inhibition Material ofAlkali-silica Reaction in Fully-Graded Concrete. Materials Science. 2020;26(3):363-372. Malhotra VM, Mehta PK. High-performance, high-volume fly ash concrete: materials, mixture proportioning, properties, construction practice, and case histories. Supplementary Cementing Materials for Sustainable Development, Incorporated. Ottawa Canada, 2002: 101p. Falade F, Ikponmwosa E, and Fapohunda C. Potential of Pulverized Bone as a Pozzolanic material. International Journal of Scientific & Engineering Research. 2012; 3(7): 1-6. Evon, D. Is This ‘Goliath Skeleton’ Real? Retrieved from: https://www.snopes.com/fact-check/is-this-goliath-skeleton-real/; (2018). BS 1881-116. Testing concrete. Method for determination of compressive strength of concrete cubes. 1983. ASTM, C78M. Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading). ASTM International, West Conshohocken, PA. 2018. Ahmed T, Burley E, Rigden S, Abu-Tair AI. The effect of alkali reactivity on the mechanical properties of concrete. Construction and Building Materials. 2003;17(2):123-144. Smaoui N, Berube MA, Fournier B, Bissonnette B, Durand B. Effects of alkali addition on the mechanical properties and durability of concrete. Cement and concrete research. 2005;35(2):203-12. Ankit K. Kisku N. Effect of silica fume and fly ash as partial replacement of cement on strength of concrete. International Journal of Innovative Research in Science, Engineering and Technology. 2016;5(10), 18618 – 18624. Subbaramaiah G, Sudarsana HR, Vaishali GG. Effect of addition and partial replacement of cement by wood waste ash on strength properties of structural grade concrete. International Journal of Innovative Science, Engineering & Technology. 2015; 2(9): 736-743 Olutaiwo AO, Yekini OS, Ezegbunem II. Utilizing Cow Bone Ash (CBA) as partial replacement for cement in highway rigid pavement construction. SSRG International Journal of Civil Engineering. 2018; 5(2): 13-19. Adanikin A, Falade F, Olutaiwo AO, Faleye ET. Ajayi AJ. Investigation of the effect of Alkali-Silica Reaction (ASR) on Properties of Concrete Pavement Admixed with Cow Bone Ash (CBA) by Electrical Resistivity Method. IOP Conf. Series: Materials Science and Engineering. 2019, 640(1): 1-9 Kadyali LR. Lal NB. Principles and practices of highway engineering including expressways and airport engineering. (Khanna Publishers, New Delhi). 2014. Marzouk H. Langdon S. The effect of alkali aggregate reactivity on the mechanical properties of high and normal strength concrete. Cement and Concrete Composites. 2003;25: 549–556. Giaccio G, Zerbino R, Ponce JM, Batic OR. Mechanical behavior of concretes damaged by alkali-silica reaction. Cement and Concrete Research. 2008;38(7):993-1004.

In this study, the effects of expansion agents on the compressive strength and frost resistance of concrete in the cold region of Northwest China were studied, and the effects of different amounts of expansion agents on the compressive strength and freeze-thaw cycle performance of concrete were analyzed experimentally, and the improvement mechanism of expansion agents on the frost resistance of concrete was revealed by combining the mass loss rate, relative dynamic elastic modulus attenuation and microstructure analysis. The results show that 10% expansion agent can improve the working properties of concrete, improve its compressive strength, and enhance the ability to resist freeze-thaw cycles. The expansion agent can effectively reduce freeze-thaw damage by compensating for shrinkage and optimizing the pore structure, thereby improving the frost resistance of concrete in the low temperature environment in the cold region of Northwest China.

By considering the adverse environmental impacts of the cement manufacturing process, there have been many efforts for cement replacement by supplementary cementitious materials (SCMs), which can enhance the produced concrete performance while reducing cement consumption. This study evaluated the effects of various proportions of silica fume (SF), waste glass powder (WGP), and ground granulated blast furnace slag (GGBFS) on the mechanical and durability properties of concrete. The properties evaluated in this study include compressive, tensile, and flexural strength, magnesium sulfate and sulfuric acid attack, surface resistivity, rapid chloride penetrability test (RCPT), water absorption, depth of penetration of water, and microstructure analysis by scanning electron microscopy (SEM). The results of compressive, tensile, and flexural strength, chloride ion penetrability, and water absorption tests showed that adding 5% of SF to mixtures containing 10% WGP or 10% GGBFS improved concrete performance significantly due to packing density and synergistic effect; however, adding 5% of SF to concrete mixtures decreased the resistance against the magnesium sulfate and sulfuric acid attack. The binary mixture of 15% of WGP showed appropriate performance against the magnesium sulfate and sulfuric acid attack, which may be due to the sacrificial nature of WGP. In addition, the binary mixtures of 15% of WGP and 15% of GGBFS reduced the depth of penetration of water by 45%. Microstructure analysis by SEM showed that the presence of SF, along with WGP and GGBFS, improves the packing density. Finally, adding 5% of SF is suggested to improve the properties of concrete mixtures containing WGP and GGBFS.

A study on the integrated implementation of supplementary cementitious material and coarse aggregate for sustainable concrete

Compressive strength, microstructure and thermal analysis of autoclaved and air cured structural lightweight concrete made with coal bottom ash and silica fume

Diatomite is a siliceous sedimentary rock containing amorphous silica, which can be used as a green mineral admixture to improve the properties of concrete. This study investigates the affecting mechanism of diatomite on concrete performance by macro and micro tests. The results indicate that diatomite can reduce the fluidity of concrete mixture and change its water absorption, compressive strength, resistance to chloride penetration (RCP), porosity, and microstructure. The low fluidity of concrete mixture containing diatomite can reduce workability. With increasing diatomite as partial replacement for cement in concrete, water absorption of concrete decreases before increasing, while compressive strength and RCP rise first and then drop. When diatomite is added to the cement at a content of 5% by weight, the concrete has the lowest water absorption and the highest compressive strength and RCP. Through the mercury intrusion porosimetry (MIP) test, we determined that the addition of 5% diatomite reduces the porosity of concrete from 12.68% to 10.82% and changes the proportion of pores with different sizes in concrete, the proportion of harmless and less harmful pores increases, and the proportion of harmful pores reduces. Based on the microstructure analysis, the SiO2 in diatomite can react with CH and produce C-S-H. C-S-H is responsible for developing concrete because it fills pores and cracks, forms a platy structure, and makes the concrete much denser, thereby improving its macroscopic performance and microstructure.

In the current investigation is presented the prospective substitution of cement and fine aggregates with fine slag material (Alccofine 1203) and coal bottom ash, respectively. The investigation was carried out in two steps, viz. Phase I and Phase II. In Phase I, a control mix was designed with basic ingredients of concrete, and then fine aggregates were partially replaced with five percentages (10%, 20%, 30%, 40% and 50%) of coal bottom ash (CBA). To improve the characteristics of coal bottom ash concrete mixtures, ultra-fine slag material, i.e., Alccofine 1203 (an innovative ultra-fine slag material, low calcium silicate, which offers reduced water demand depending upon the concrete performance) was used as a partial replacement of cement. In Phase II, the inspected effect of replacing 5%, 10%, 15% and 20% cement with Alccofine, a concrete mix containing 40% coal bottom ash, on concrete properties such as workability, compressive strength, split tensile strength, flexural strength, pulse velocity, rapid chloride penetration along with a microstructural analysis using SEM was studied. It was concluded from cost analysis that the 15% replacement of cement with ultra-fine material Alccofine in 40% coal bottom ash concrete achieved the properties of high-strength concrete, with an 8.14% increase in cost compared to the control increase. The significance of this work lies in the fact that we achieved a high-strength concrete by using 40% industrial waste, i.e., coal bottom ash, as a partial replacement of fine aggregates in combination with the 15% Alccofine inclusion as a partial replacement of cement. About 58% improvement in compressive strength was recorded for 40% coal bottom ash and 15% Alccofine mix.

Valorization of recycled FRP materials from wind turbine blades in concrete

The growth of Malaysia has caused many industries to grow rapidly, especially construction industries due to the demand for more homes, buildings, and infrastructure. The production of concrete and mortar is highly requested. Therefore, the demand for fine aggregate becomes higher because fine aggregate is one of the main elements in concrete and mortar production. The high demand for fine aggregates will create a worrying situation where the fine aggregate crisis will worsen. An alternative was introduced to replace the fine aggregate known as palm oil fuel ash (POFA) in order to reduce the use of natural resources such as fine aggregates and lead to the reduction of fine aggregate mining activity. POFA produced from palm oil fibre, palm oil shell, and mesocarp at high temperature has no benefits in the commercial return. Thus, POFA that has accumulated in landfill has the ability to create environmental pollution. Due to the pozzolanic behaviour of POFA, it could be relevant when POFA is used in the production of mortar as a partially fine aggregate replacement. There is a limited study on the effects of POFA as a partially fine aggregate replacement in the production of mortar. The aim of this research is to study the effects of POFA on the workability of fresh mortar, and for the hardened mortar, compressive strength and microstructural analysis will be analysed. A total of 45 cubes with dimensions of 100 mm × 100 mm × 100 mm were cast at different percentages of POFA at 0%, 2.5%, 5%, 7.5%, and 10% by the weight of fine aggregates. Slump and flow table tests were conducted during the casting process to determine the workability. All the specimens were water cured at days 3, 7, and 28 before being tested with a compression test and scanning electron microscope (SEM) on the hardened mortar. It was discovered that 0% POFA recorded the highest workability. Furthermore, the laboratory results showed that the 2.5% POFA in the mortar recorded the highest compressive strength compared to other specimens. Moreover, the microstructure of the mortar specimen was observed to be denser, and the pores were refined with the presence of POFA, compared to the control specimen. Based on the findings, this research enables us to give an understanding of the effect of POFA incorporated in mortar as a partially fine aggregate replacement in terms of workability, compressive strength, and microstructural analysis. Based on the results from this research, the advantage of POFA can be fully utilized and can help reduce the environmental problems.