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The mechanical properties of four types of concrete, tested under multiaxial (biaxial tension–compression, triaxial tension–compression–compression) dynamic (strain rates of 10−5, 10−4, 10−3 and 10−2 s−1) complex stress states with different stress ratios, were compared and analysed. The same test apparatus was used in order to avoid test errors caused by differences of the triaxial testing machine. The aim of this work was mainly to determine the dynamic multiaxial (DM) strengths of the four concrete types. It was found that the mechanical behaviour of the four concretes was similar to a certain extent. The DM strengths of the concretes increased with an increase in strain rate and their DM strengths in any direction were lower than the concrete static strength under uniaxial tension and compression. The influence of strain rate and stress ratio on the DM strengths of the concretes were compared and analysed. A unified failure criterion was developed, expressed by the octahedral stress space criterion, of the various concrete types under DM tension and compression. This investigation provides a theoretical foundation for the design and checking of structures subjected to DM load conditions.

The main concerns of civil engineering officials and researchers is to produce the structural lightweight concrete, which is cost effective, sustainable, durable and can behave satisfactorily under structural applications. Therefore, the use of industrial waste as an alternative lightweight aggregate (LWA) to build eco-friendly stable structures that have many realistic and financial benefits. Coconut shell (CS) is a waste industrial by-product and was successfully utilized to produce reasonable strength lightweight aggregate concrete. Four different types of concrete mix were developed with first three samples having 0%, 50%, 100% replacement of NWA with coarse CS, however, in fourth mixture, the combination of NWA and CS aggregates was considered at 50% substitution levels and in addition, the 25% of cement was replaced with bagasse ash. In conclusion, it was found that the combinations of CS and NWA increases the workability of the concrete mixes and showed 28-day compressive strength between 30 and 39 MPa with oven-dried density range of 1856 to 2103 kg/m3. Mix containing 50% CS and 25% bagasse ash showed significantly better performance in terms of drying shrinkage with the percentage reduction of about 18% compared to the coconut shell concrete (CSC), and this value was about 14% higher than the conventional normal weight concrete (NWC). In shear behavior, the contribution of CS and NWAs with 25% of cement replacement with bagasse ash showed higher shear performance compared to other beams containing 50% and 100% Coconut shell aggregates (CSA).

An experimental investigation into the shear behavior of Glass Fiber Reinforced Polymer (GFRP) reinforced concrete beams is presented. The study also looks at the effectiveness of shear strengthening of such beams using externally-bonded Carbon Fiber Reinforced Polymer (EB-CFRP) sheets and investigates the possibility of interaction between internal and externally bonded shear reinforcement. A total of 18 beams, 2.4 m long with a rectangular cross-section of 300x200, reinforced with GFRP bars and stirrups were tested. Three types of concrete were used in this study; ordinary Portland cement (OPC) concrete, Fiber Reinforced concrete (FRC), and Geopolymer concrete (GPC). Six beams, two for each concrete type, severed as control while the other twelve were strengthened using “U” shape EB-CFRP sheets. The CFRP sheets were placed in two different arrangements, above and in-between internal stirrups locations. The results indicate that GFRP is a viable reinforcement for GPC, OPCC, and FRC, whereas EB-CFRP proves to be a feasible strengthening technique for such composite systems. The gain in shear strength for EB-CFRP strips beams on the location of internal stirrups is 5–10% lower as compared to the other arrangement. The difference in the strength gain may indicate a possible interaction between the internal and external shear reinforcement.

This research studies the performance of simply supported spliced reinforced concrete one-way slab by using different types of concrete in the splice region, which are (normal concrete NC, high strength concrete HSC, reactive powder concrete RPC, and slurry infiltrated fiber reinforced concrete SIFCON). Five specimens have been used; one cast as one unit as a reference specimen and the other forming from three pre-cast panels from NC and two splice regions. Each specimen has 2130 mm total length, 600 mm width, and 100 mm thickness. The experimental work includes several parameters for a study which are first cracking load for the precast panels as well as the first cracking load in splice region, ultimate load, crack width, strain in concrete, load–deflection curves, and failure mode. The experimental work shows that the ultimate load Pu increased when using RPC and SIFCON in splice region greater than non-spliced specimen by 44.38% and 23.48% respectively, and also without damage in the splice region. This high performance is related to the improve in properties of RPC and SIFCON. While no improvement in performance when using normal concrete and high strength concrete in the splice region.

The present paper aims to develop sustainable concrete to reduce the impact of concrete on environment using groundnut husk ash. In the present study, Life Cycle Assessment (LCA) of concrete is evaluated in terms of Global Warming Potential (GWP), Acidification Potential (AP), and Eutrophication Potential (EP) which indicates the impact of Carbon Dioxide (CO2) and other gases emission on environment during manufacturing of concrete. Six types of concrete cubes i.e CM, G-2.5, G-5, G-7.5, G-10, G-12.5, and G-15 designed concrete are manufactured by replacing cement with GHA by mass at different replacement levels (0%,2.5%, 5%, 7.5%, 10%, 12.5% and 15%).Cubes were tested for compressive strength after 7 and 28 days. Results indicated that upto 12.5% replacement of cement with groundnut husk ash (GHA) by mass, the compressive strength of GHA was more than the characteristic strength of M20 grade concrete. LCA of control mix and GHA concrete was done from cradle – to – gate boundaries. In control mix concrete, cement has the highest environmental impact about 80%, 73% and 54% of total impact for GWP, AP and EP respectively Results indicated that by utilizing GHA, reduction of 10%, 9.1%, and 7.2% in GWP, AP, and EP impact values occurs respectively. Therefore, it is concluded that the use of groundnut husk ash in concrete will lessen the impact of carbon dioxide and other green house gases (GHG) on environment and adds to the sustainability aspect by utilizing waste.

Various types of concrete piles with dimensions of square, triangle, or circle are produced to be used as deep foundations. To get a solid superstructure, a foundation with a high bearing capacity is needed, the bearing capacity of the pile depends on local soil conditions, but if the soil is soft soil, an investigation is needed to determine the carrying capacity. The research was conducted to obtain the carrying capacity of the pile by means of manual calculations which will then be compared with calculations using SAP 2000 version 14. Soil data analyzed were sondir and boring data which were the results of the laboratory in the form of soft soil data which would be analyzed manually with took a sample of rectangular type piles with materials from K-600 concrete. From the research results obtained square stakes with dimensions of 20 x 20 cm which were analyzed with Sondir data, Boring data, and analysis based on SAP 2000 software, the relative carrying capacity values were the same, namely 13.18 tons and 13.31 tons, but for analysis using power software support the pile is higher with a value of 15.62 tons. At the dimensions of the stake 25 x 25 cm and 30 x 30 cm the value of the carrying capacity still tends to be the same as the value of 17.06 tons and 18.64 tons for the dimensions of 25 x 25 and the value of the carrying capacity of 21.17 tons and 24.76 tons from the analysis results. dimensions of 30 x 30 cm but there is already a difference in carrying capacity but relatively small, for the calculation of the software still produces a larger carrying capacity value, namely 22.24 tons and 29.95 tons, while for fishing rods with dimensions of 45 x45 cm, it has a pile bearing capacity, especially with analysis SAP 2000 software produces a relatively large carrying capacity value of 73.69 tons so that it can be concluded that the manual calculation to obtain the bearing capacity of the pile. The value is smaller than the calculation in the SAP 2000 software.

In concrete mixing plan, we usually encounter a combination of aggregates including sand, the amount of cement, which is actually the criterion of concrete grade, and the volume of water consumed. Changes in the quality and quantity of these components actually create the usual types of concrete. But the attitude that formed the basis of this research is based on the change in the nature of the components of the concrete mixing design. Removal of water and cement from the mixing plan and replacement of polymeric materials as well as the use of mixed LECA aggregates instead of aggregates is the basis of this research. In this paper, by examining and selecting LECA grain style and pre-treatment (hydrophobicity and coupling), in a constant ratio of resin, concrete samples were selected from three dimensional categories. After making the samples, flexural strength test was performed on them and the results were analyzed. Various compounds and processes have so far been proposed in the lightweight concrete mixing scheme. The distinctive point of this study is the use of lightweight expanded clay concrete with heat-treated acrylic polymer (crosslinking constituents) and related coupling agents. It is also important to select and apply the right amount of hydrophobic nanoparticles for hydrophilic surface hydrophobicity. Hydrophobicity was possible due to the non-polar nature of the acrylic polymer and the use of hydrophobic nanomaterials.

This article evaluates the feasibility of using concrete waste from precast production as recycled aggregate in concrete. The processing of concrete waste employed a jaw-hammer crusher and a sieve, producing three types of Recycled Concrete Aggregate (RCA). After their characterization, RCA was incorporated in two types of concrete used in the precast factory: a flowing concrete (FC), slump 220 mm, employed in columns and beams; and the second one, a no-slump extruded concrete (NSC), used for hollow core slabs. X-Ray diffraction, thermogravimetric analysis and scanning electronic microscopy showed phases from the hydrated cement paste and the original aggregate. Results of mechanical performance showed that RCA did not influence the compressive strength but influenced other properties such as water absorption and modulus of elasticity. Lastly, it was concluded that RCA obtained in the precast factory showed great potential to be used within the factory production process.

The aim of this study was to predict the corrosion of cement concrete (CC) and sulfur concrete (SC) in sewer systems using three artificial intelligence (AI)-based techniques: Adaptive NeuroFuzzy Inference System (ANFIS), Genetic Programming (GP), and Multi Expression Programming (MEP). Two sets of chemical experiments in acidic solutions and biological tests using Thiobacillus thiooxidans were conducted to investigate the corrosion in concrete samples. For both tests, weight loss was used as the indicator of corrosion. Time and pH values in chemical tests were selected as the input variables, while in biological experiments only time was selected as the input variable. In addition, compressive strength (CS), weight loss, water absorption, and hole index ratio (HIR) were selected as the output variables for both experiments. Based on the results obtained in both experiments, a database of 256 values was established to train and test the prediction models. According to the results, all AI-based models were able to predict the weight loss with reasonable accuracy. In contrast, the proposed MEP model outperformed other models with R2 of 92.1 (training) and 87.9 (testing) for CC and 99.5 (training) and 97.7 (testing) for SC, respectively. This study shows that machine learning-based models can help engineers estimate the corrosion of concrete pipes in sewer systems. • ANFIS, GP and MEP models were used to model corrosion in cement and sulfur concrete • All AI-based methods were able to predict corrosion in both types of concrete • MEP showed better performance than other methods in the prediction of corrosion

This paper presents an experimental investigation on a recently developed prefabricated shallow steel-concrete composite flooring system composed with lightweight concretes. The novel flooring system is consisted of two main structural components: two C-channel steel beams and a partially encased concrete floor. The concrete floor, which is in the form of T-ribbed slab sections, was constructed using three types of concrete (reinforced normal concrete, reinforced lightweight aggregate concrete, and reinforced ultra-lightweight aggregate concrete), and the steel edge beams which partially encase the floor slab and provide clear and straight finish edges. Three full-scale push-out tests were conducted to investigate the effect of the lightweight concrete on the longitudinal shear behaviour of the new shear connection system, made of web-welded shear stud connectors. It was observed that specimens with lightweight concretes demonstrated additional ductility when compared with specimen using normal concrete, and the failure mode of the shear studs alters. It is confirmed that the specimen with normal concrete has reached a higher failure shear load.

Strengthening the seismic deficient beam-column joints (BCJs) in reinforced concrete structures is mostly adopted to avoid any devastating consequences of high-intensity earthquakes. To evaluate the performance of BCJs against seismic action, experimental testing of BCJs under cyclic loading is a time-consuming and cost-intensive work due to the requirement of large-scale instrumentation and testing. This paper reports a study on the numerical and analytical modeling of the seismic behavior of BCJs built using normal concrete and retrofitted with ultra-high performance fiber reinforced concrete (UHPFRC). A computer simulation using the nonlinear finite element (FE) method was developed considering a concrete damage approach in modeling both types of concrete, i.e., normal concrete (substrate) and UHPFRC (overlay). The interface between the substrate and overlay was modeled as a cohesive element. The properties of this bonding interaction were experimentally evaluated based on the results of the push-out test. The simulation results benchmarked with the experimental data of a previously published study. It was found that the proposed FE model is in good agreement with the experimental behavior of seismically tested specimens in terms of global load–displacement, ultimate load, and damage evolution. In addition, the use of surface-to-surface cohesive elements played an important role in the bonding interface under cyclic loading. Additionally, an analytical model was developed to predict the shear capacity after retrofitting the BCJ. The results obtained by using the analytical model were consistent with the corresponding experimental values. Finally, a parametric study was carried out to examine the effects of the thickness of UHPFRC jacketing and longitudinal reinforcements ratio of the beam on the performance of the retrofitted BCJs.

Portland cement concrete is the most commonly used construction material in the world for decades. However, the searches in concrete technology are remaining growing to meet particular properties related to its strength, durability, and sustainability issue. Thus, several types of concrete have been developed to enhance concrete performance. Most of the modern concrete types have to contain supplementary cementitious materials (SCMs) as a partial replacement of cement. These materials are either by-products of waste such as fly ash, slag, rice husk ash, and silica fume or from a geological resource like natural pozzolans and metakaolin (MK). Ideally, the utilization of SCMs will enhance the concrete performance, minimize environmental pollution and mitigate the drawbacks of cement production attributed to the highly CO2 emission. In general, MK's ultra-fineness and high pozzolanic activity are exhibited a remarkable performance of concrete in terms of strength and durability. However, the filler effect, acceleration of cement hydration, and the pozzolanic reaction with calcium hydroxide (CH) are the main factors influencing the performance of metakaolin as a cementitious material. Therefore, numerous researches have been undertaken on inclusion MK in concrete and mortar and production of (free-cement concrete) geopolymer concrete. This paper reviews some of previous native researches on effect of using Iraqi metakaolin as a pozzolanic material in different types of concrete. The standpoint of this review will guide the researchers on the importance of utilization of local MK and highlight the missing researches toward completing a comprehensive understanding of incorporation Iraqi-metakaolin in concrete technology.

In recent times, the production of polyethylene ground plastics has increased markedly in the Philippines. However, current levels of their usage and disposal generate several environmental problems. Recycling is one of the most important actions that are being made to reduce these impacts. The present study used polyethylene ground plastic wastes to investigate their possible use as plastic aggregate in concrete application. The shredded plastic wastes were used in concrete with partial replacement of ½ kg and 1kg by volume of conventional coarse aggregate. Three types of concrete specimens including one without plastic aggregate were used in the study for comparison. All the concrete specimens were tested for their different mechanical properties after a curing period of 28 days. Various physical properties of all aggregates and fresh concrete properties were also tested in the laboratory, these include pound per square inch (psi), Mega Pascal (MPa), Kilo Newton (KN), and the type of fracture. The test for psi, MPa, and kN resulted that concrete mixtures with 1kg ground plastic produced the best result among the three samples having 3150 Psi, 21.7 MPa, and 395.7 KN, respectively. Moreover, the specimens were loaded under a monotonic uniaxial compressive load up to failure by using MATEST hydraulic testing machine with the indicator of kN. The result showed that both standard mixtures of concrete and the standard mixture of concrete with ½ kg polyethylene ground plastic have a comparison infraction that has a result of an SW-Shear Wedge of Type 5, while the standard mixture of concrete with 1kg polyethylene ground plastic has a conical type of a fracture. Based on the several tests conducted, it is concluded that the standard concrete mixture with 1kg polyethylene ground plastic provided the best result compared to other specimens. Furthermore, the use of polyethylene ground plastic waste in the standard concrete mixture provides some advantages like on reduction of plastic wastes, prevention of environmental pollution, and energy saving.

This paper presents the mechanical behaviour of concrete mixes made with recycled aggregate by replacing the natural aggregate with crushed concrete from pavement demolition. The purpose of this study was to determine the feasibility of using recycled aggregate from pavement demolition to make new concrete for pavement applications. Considering a control mix without recycled aggregate (RCA0) designed for a compressive strength of 34 MPa, two types of concrete mixes with 50% (RCA50) and 100% (RCA100) replacement percentage of natural coarse aggregate by recycled aggregate were made. The resulting concrete specimens were tested at three different curing ages, 7, 14, and 28 days. The results of this study showed that the compressive and flexural strengths decreased for all two mixes as the recycled aggregate content increased, while the density was slightly affected. A new model based on multiple linear regression analysis of the data from this study and other 14 studies from the literature was developed. The model can be used to predict the compressive strength of general-use concrete mixes with recycled aggregate (20–40 MPa) considering both the recycled aggregate content and the curing age of concrete. A good correlation was found between the compressive strength and the two parameters investigated. Given the predictions of this model, it is recommended not to use more than 30% recycled concrete aggregate in the production of new concrete in order not to affect its strength.

The employment of phase change materials (PCMs) in the construction of concrete building components has engaged many researchers’ interest. In this study, a novel reduced-scale experiment is employed to perform a parametric investigation of the thermal performance of PCM-integrated wall specimens considering two types of concrete, two types of PCM, and different thicknesses of the concrete and PCM layers. Moreover, three different ambient temperature profiles of a summer day in three different cities were considered as the outside ambient temperature to evaluate the performance of each PCM under different temperature conditions. The test procedure is capable of evaluating the thermal performance of different wall configurations under various temperature conditions. The inside temperature variations of the wall specimens were monitored as the thermal performance criteria. In consequence, integrating the PCM layer with normal concrete or with slimmer concrete layers resulted in better thermal performance of PCM in absorbing heat in comparison to lightweight concrete or thicker specimens due to the considerable effect of density and specific heat capacity of different types of concrete. Moreover, the compatibility of the melting temperature of PCMs with the ambient temperature of the considered cities in summer is assessed and discussed.

Attempts to modify cement-based mixtures and to improve their properties have always attracted the attention of researchers. Favorable effects of nanoparticles, such as small particle size, high reactivity, and great surface area, have made them be used as one of the best replacements of cement. This paper aims to review the previous researches conducted regarding the effects of nanoparticles on the properties of concretes. Influence of various types of nanoparticles on the workability of fresh composite, mechanical properties such as compressive strength, flexural strength, splitting tensile strength, modulus of elasticity, and abrasion resistance, and durability-related properties such as water absorption, chloride ion penetration, resistance to frost, shrinkage, and carbonation of concrete is discussed.

The implementation of novel machine learning models can contribute remarkably to simulating the degradation of concrete due to environmental factors. This study considers the sulfuric acid corrosive factor in wastewater systems to simulate concrete mass loss using five machine learning models. The models include three different types of extreme learning machines, including the standard, online sequential, and kernel extreme learning machines, in addition to the artificial neural network, classification and regression tree model, and statistical multiple linear regression model. The reported values of concrete mass loss for six different types of concrete are the target values of the machine learning models. The input variability was assessed based on two scenarios prior to the application of the predictive models. For the first assessment, the machine learning models were developed using all the available cement and concrete mixture input variables; the second assessment was conducted based on the gamma test approach, which is a sensitivity analysis technique. Subsequently, the sensitivity analysis of the most effective parameters for concrete corrosion was tested using three different approaches. The adopted methodology attained optimistic and reliable modeling results. The online sequential extreme learning machine model demonstrated superior performance over the other investigated models in predicting the concrete mass loss of different types of concrete.

The development and research of a new formulation of concrete integrating natural resources such as sands (from dunes and/or quarries) as well as waste from steel factories in the form of granulated slag from blast furnaces lead to the development of new sand concretes for which the improvement of specific properties will lead to a search for an agreement between production cost and performance. The objective of this research is to study the influence of the dosage of the size of the largest aggregate on the workability of sand concretes as well as on the compressive strength at 7 days, 14 days and 28 days. Five types of concrete are made by substituting aggregates (dune sand and quarry sand) with each other and with different percentages (100%, 75%, 50%, 25% and 0%). The results show that the workability of fresh concrete is considerably influenced by the nature of the sand; the richer the sand in coarse elements, the fineness modulus increases and the more handling improves. In the hardened state, the results show that optimization of the compressive strength is achieved when a good homogeneity of the concrete is achieved and when a large percentage of coarse sand is mixed with a small percentage of fine sand.

The bonded behaviour between epoxy-coated steel bars (ECSB) and seawater sea sand recycled concrete (SSSRC) were systematically analysed using pull-out tests. Five different parameters were considered: including types of concrete (SSSRC, recycled concrete and ordinary concrete) and steel bars (ECSB and ordinary steel bars (OSB)), the ratio of bond length to bar diameter (3, 5 and 8), and concrete strength (C20 and C25) and thickness of concrete cover (42 mm and 67 mm). The failure pattern, bond strength and bond-slip curve of specimen were analysed. The results indicate that the failure mode of specimen was pull-out failure, and the concrete type changed the failure surface of specimen. The specimen with OC exhibited high bond strength compared to specimen with SSSRC. Increasing concrete cover thickness increased the bond strength of seawater sea sand recycled concrete-ECSB (SSSRC-ECSB), while its bond strength decreased with the increase in the bond length. It can be found that the bond-slip curve of SSSRC-ECSB was similar to that of ordinary concrete-OSB (OC-OSB). SSSRC and ECSB obviously reduced the curvature of bond-slip curve, and the decline of curve changed with the types of concrete and steel bars used. Finally, a general expression of bond-slip curve was derived, which could provide a basis for the practical application of SSSRC.

The evolution of nanotechnology brings materials with novel performance and during last year’s much attempt has been established to include nanoparticles especially nano-silica (NS) into the concrete to improve performance and develop concrete with enhanced characteristics. Generally, NS is incorporated into the self-compacting concrete (SCC) aiming to positively influence the fresh, mechanical, microstructure, and durability properties of the composite. The most important mechanical property for all types of concrete composites is compressive strength. Therefore, developing reliable models for predicting the compressive strength of SCC is crucial regarding saving time, energy, and cost-effectiveness. Moreover, it gives valuable information for scheduling the construction work and provides information about the correct time for removing the formwork. In this study, three different models including the linear relationship model (LR), nonlinear model (NLR), and multi-logistic model (MLR) were proposed to predict the compressive strength of SCC mixtures made with or without NS. In this regard, a comprehensive data set that consists of 450 samples were collected and analyzed to develop the models. In the modeling process, the most important variables affecting the compressive strength such as NS content, cement content, water to binder ratio, curing time from 1 to 180 days, superplasticizer content, fine aggregate content, and coarse aggregate content were considered as input variables. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the coefficient of determination (R2) were used to evaluate the performance of the proposed models. The results indicated that the MLR model performed better for forecasting the compression strength of SCC mixtures modified with NS compared to other models. The SI and OBJ values of the MLR model were 18.8% and 16.7% lower than the NLR model, indicating the superior performance of the MLR model. Moreover, the sensitivity analysis demonstrated that the curing time is the most affecting variable for forecasting the compressive strength of SCC modified with NS.

Ultra-high-performance concrete (UHPC) is a kind of high-tech cementitious material with superb mechanical and durability properties compared to other types of concrete. However, due to the high content of cement and silica fume used, the cost and environmental impact of UHPC is considerably higher than conventional concrete. For this reason, several efforts around the world have been made to develop UHPC with greener and less expensive local pozzolans. This study aimed to design and produce UHPC using local fly ash available in Colombia. A numerical optimization, based on Design of Experiments (DoE) and multi-objective criteria, was performed to obtain a mixture with the proper flow and highest compressive strength, while simultaneously having the minimum content of cement. The results showed that, despite the low quality of local fly ashes in Colombia, compressive strength values of 150 MPa without any heat treatment can be achieved.

Construction is a serious environmental problem and a challenge for people who concerned with sustainability in the construction field. Previous studies showed positive results for the use of recycled aggregates in the concrete production. This study portrays the results for utilizing construction debris for casting different types of concrete blocks. The recycled concrete debris was used in different ratios (0%, 50%, and 100%) in replacement for natural coarse aggregates for different targeted compressive strength (B250, B300, B350 and B400). Two types of water (pure and sea water) were used for curing the blocks. In addition, hollow block and paving block were casted with different ratios of recycled aggregate (0%, 20%, 45% and 100%) and cured with two types of water. The results showed a decrease in compressive strength with the increase recycled aggregate content. It was also noticed that the absorption capacity increases with high recycled aggregate content.

Recycled concrete aggregate (RCA) obtained from construction and demolition waste has been widely studied for its feasible uses to replace natural aggregate in different types of concrete products. For the past few decades, efforts have been made to modify or/and improve conventional mixing approaches for the use of RCA in concrete, such as two-stage mixing approach, paste wrapped recycled aggregate approach, etc. However, there was no direct comparison between these approaches. Therefore, this paper investigates the synergistic effect of pre-carbonated slurry and concrete mixing sequence on the performance of self-compacting modified mortar (SMM) containing RCA and aims to compare with other four mixing approaches. Fresh properties and mechanical strengths of SMM and the characterization of interfacial transition zone were studied and compared. Results proved that a denser matrix and an interfacial transition zone (ITZ) with a better quality reflected a better mechanical performance. Among five mixing approaches, SMM samples produced by pre-carbonation approach had slightly larger drying shrinkage, but exhibited enhanced flowability and reduced permeable voids. The compressive strength and flexural strength increased by about 12.3% and 12.0% compared to those made by normal mixing sequence. Backscattered electrons (BSE) images and Vickers microhardness results also revealed a denser interface between new cement matrix and RCA for the sample prepared with pre-carbonation approach.

PurposeConcrete-filled steel hollow (CFHS) column is an innovation to improve the performance of concrete or steel column. It is believed to have high compressive strength, good plasticity and is excellent for seismic and fire performance as compared to hollow steel column without a filler.Design/methodology/approachExperimental and numerical investigation has been carried out to study the performance of CFHS having different concrete in-fill and shape of steel tube.FindingsIn this paper, an extensive review of experiment performed on CFHS columns at elevated temperature is presented in different types of concrete as filling material. There are three different types of concrete filling used by the researchers, such as normal concrete (NC), reinforced concrete and pozzolanic-fly ash concrete (FC). A number of studies have conducted experimental investigation on the performance of NC casted using recycled aggregate at elevated temperature. The research gap and the recommendations are also proposed. This review will provide basic information on an innovation on steel column by application of in-filled materials.Research limitations/implicationsDesign guideline is not considered in this paper.Practical implicationsFire resistance is an important issue in the structural fire design. This can be a guideline to define the performance of the CFHS with different type of concrete filler at various exposures.Social implicationsUtilization of waste fly ash reduces usage of conventional cement (ordinary Portland cement) in concrete production and enhances its performance at elevated temperature. The new innovation in CFHS columns with FC can reduce the cost of concrete production and at the same time mitigate the environmental issue caused by waste material by minimizing the disposal area.Originality/valueReview on the different types of concrete filler in the CFHS column. The research gap and the recommendations are also proposed.

This paper investigates the effect of nano-papyrus cane ash as an additive on concretes’ mechanical and physical properties. Three types of concrete mixtures, 1:2:4, 1:1.5:3, and 1:1:2 were prepared for each mixture, nano-papyrus ash was added in five different dosages of 0.75, 1.5, 3, 4.5, and 6% by weight of cement; therefore, eighteen mixes would be studied in this work. Physical properties represented by dry density and slump were also measured for each mix. Moreover, to evaluate the mechanical properties development split tensile strength and compressive strength were obtained at age (7 and 28). Results manifested that the adding of nano ash developed the compressive strength and split tensile strength of concrete and the maximum enhancement recognized in the mixes with a content of 4.5% nano-papyrus in each studied mixture in this work. The slump test results indicated that the workability of concrete increased with adding nano-papyrus ash gradually with increasing nanoparticles' content. As well as, dry density was significant increased with nano-papyrus ratio; greater values were recorded in mixtures with 1.5-4.5% content of nano-papyrus. When comparing the concrete mixes used, it was found that the best results were obtained with 1:1:2 mixtures. This remarkable improvement in concrete properties considers the nano-papyrus is considered a cement economical and useful replacement for traditional construction material. Doi: 10.28991/cej-2021-03091649 Full Text: PDF

Environmental degradation resulting from waste disposal from coal industry and palm oil mills along with greenhouse gasses released by cement manufacturing industry needs to be resolved. Realizing that the use of free granite lightweight aggregate concrete is rewarding in terms of environmental sustainability and construction cost reduction through reduced foundation size, the present research delves further in oil palm shell (OPS) lightweight concrete research. The influence of fly ash as partial cement replacement on compressive strength, porosity and acid resistance of OPS lightweight aggregate concrete were investigated. Five types of concrete mixes were casted by replacing fly ash from 0%, 10%, 20%, 30% and 40% by weight of cement. All the cubes were subjected to air curing for 28 days. The compressive strength and porosity of concrete were conducted 28 days of curing age. The acid resistance of concretes was evaluated by measuring the mass loss of the cubes after immersed in sulphuric acid solution for 1800 h. The findings show that OPS lightweight aggregate concrete exhibit strength reduction and increment in porosity value when more fly ash is used. Concrete produced with lesser quantity of fly ash experience lower mass loss and strength drop after immersed in acidic environment.

The invent of new construction materials and extensive research in concrete technology and cement chemistry has proved that apart from proportioning concrete for high strength it is very important to design a concrete mix for high performance in terms of diagnosing damage like smart materials. The use of mineral and chemical admixtures in concrete has facilitated the material scientists to invent special types of concrete to suit the current application. Materials that are used in concrete like steel fibres, carbon nano fires (CNF) and carbon nano tubes (CNT) with appropriate dosage, can impart this self-sensing property in concrete. These multifunctional smart materials have resulted in assessing the damage to structures without the need for any external sources like sensors or any structural health monitoring device like optical fibres. The inclusions of nano materials in cementitious matrix that are conductive in nature provide a new type of self-sensing composite. Self-sensing material have the ability to sense their own conditions like stress, strain, temperature and damage. This property of the material which enables itself to assess its own damage and deformation has made it a smart material for health monitoring. Appropriate use of this smart material with a well-defined sensing scheme can enhance the sensitivity of damage detection in micro level which can prevent the collapse of the structure. CNT and CNF were used in 0.1 to 0.3% by weight of cement and their electrical conductivity was measured which gives a good relation of the self-sensing properties of the material. Cyclic compressive load was conducted and the response to the piezoresistive properties of the nano composite was tested. It was observed that 0.1% of these carbon nano materials had better electrical properties.

The waste of the marble industry is the cause of many environmental problems because 70% waste and the acquisition of only 30% of the main product contributing to the high non-corrosive spill. Dump sites give a dirty look. Contaminate the top fertile soil cover, and the rivers / bodies of water that touch it irrigation and drinking water and air resources and the loss of plants and animals. The most effective solution for utilization of marble slurry is to apply to Bulk. The only sector that saves eat marble slurry at such a high level only in the construction industry. Concrete is an important building material and is used in construction industry due to its high compression strength and durability. Now a different day concrete workshops were conducted with the intention of reducing costs and unavailability of common items. This paper scans the file for strong areas of various types of concrete used using marble dumps as replacement of good integration. The pieces of marble are finely ground into powder and gradation is compared to a good standard combination of Various marble slurry structures determined in the laboratory. Sp. gravity 2.61, Fineness modulus 0.91 and the use of The marble slurry in Cement Concrete instead of Sand is 30% showing the same strength as Control i,e. 1: 2: 4. Cement Concrete 0% Marble slurry. Marble slurry can be easily used in the construction industry in preparation Cement Concrete.

Resumen: La eliminación de los residuos metálicos generados durante los procesos iniciales de fabricación en plantas industriales y talleres con maquinaria sigue siendo un gran problema. La investigación actual se ocupó de agregar los residuos metálicos producidos en el procesamiento de la maquinaria, tales como el polvo de limaduras de hierro, virutas del torno de hierro y del torno de aluminio para mejorar el rendimiento estructural de los paneles de losa nervada unidireccional. En este trabajo se consideraron dos tipos de hormigón: ferrocemento (FER) y hormigón autocompactante (SCC). Los paneles de hormigón armado con polvo de limaduras de hierro y virutas de torno giratorio de hierro mostraron un aumento en la carga máxima y una disminución en la deflexión central, mientras que los paneles con virutas de torno giratorio de aluminio revelaron un comportamiento opuesto. El efecto más significativo del uso de los desechos metálicos es su mejor resistencia a la propagación de las fisuras al aumentar la unión entre las fibras y el mortero de cemento a través de las grietas. El hecho de agregar los desechos metálicos con partículas finas mejora la resistencia del hormigón, siempre que se controle la trabajabilidad. El uso de las virutas de torno como fibra de hierro con un factor de forma específico tiene un efecto secundario debido a la formación de bolas de fibra en la mezcla de hormigón. Además, el uso de altos porcentajes de polvo de limaduras de hierro provoca la aglomeración de las partículas de polvo debido a las fuerzas de atracción magnética.

Experimental and theoretical programs are designed to investigate the effect of elevated temperature on Normal (NC), high strength (HSC) and self-compacting concrete (SCC) beams. Six steel jacket techniques designed to ass the efficiency of retrofitting after elevated temperature exposure. The more effective jacket was used for different types of concrete beams. Different beams subjected to two levels of temperature 400 °C and 600 °C for 120 min. The main parameters were steel jacket angels' size, angles orientations and positions while different confinement techniques were fillet welded steel plate and threaded bars. Steel plate retrofitting did not have a significance improvement while steel angels had a good behavior as steel jacketing. The steel jacketing especially four angles improve normal concrete beams by 280% and 160% while improve self-compacting concrete by 290% and 240% after exposed to 400 °C and 600 °C respectively. The outside orientation of top angels report acceptable behavior for beams capacity restore less than 10%. The welded plates have good results than bolts in this study.

The methodology classifying structural types of concrete buildings in the existing seismic fragility functions is too simple to estimate the fragility of existing residential buildings and neighborhood living facilities, especially those below five stories. Their structural types are dependent on information contained in the building register such as main use, total floor area, story, permission date, and first story floor area of the individual building. All of this information is not considered for classifying types in the existing functions; therefore, the goal of this study was to suggest a methodology that classifies structural types of concrete buildings by utilizing such information. The results of this study showed that the suggested methodology can classify structural types better than the existing methodology. Nevertheless, there is still a need to simplify the methodology because fragility estimation demands quickness rather than accuracy.

An experimental study on four types of coarse aggregate was conducted to produce lightweight concrete. These four types are namely; white limestone, red limestone, clay brick fragments, and pumice. Ordinary Portland cement was used for all examined mixes. Water to cement ratio (w/c) was modified according to the effect of coarse aggregate type on the workability of the resulted concrete for each mix. The reference concrete mix, which is normal concrete, water to cement ratio used was (0.5). The investigated characteristics for all concrete mixes were workability, compressive strength, dry density, absorption, and thermal conductivity. Results indicated that the aggregate type significantly affects most of the properties of lightweight concrete mixes such as workability, density, and thermal insulation for all tested types of concrete. All investigated specimens indicated improvement in terms of density, workability, and thermal conductivity when compared to the reference concrete mix. Yet, it was derived from the testing results that using pumice in lightweight concrete production is the optimum option among the other examined types. When compared to normal concrete, this type of lightweight concrete showed a 41% decrease in dry density, nearly 72.54% decrease in thermal conductivity, and about 12% increase in workability. However, it is vital to notice that due to the low compressive strength and the relatively high absorption capability for all the examined types of lightweight concrete, it is suggested to use these types of concrete for non-structural walls that are not subjected to or exposed to high humidity.

This research deals with assessing fine aggregate (sand) properties as construction materials, that were collected from the Dibdibba Formation at Tar AL-Sayed, Karbala, Iraq, in mortar, concrete, tiles, thermo-stone, solid, hollow masonry blocks and cement paste. Physical tests were carried out on five samples, the moisture content, specific gravity, density of both bulk, dry and porosity were almost varied. The tested samples show that they are unsuitable for all types of concrete, tiles types, thermo-stone and cement masonry block in terms of grain size in all fractions except that of 4.75 mm and 2.36 mm. Later all samples were treated by washing using fresh water, fine clean sand was added in an attempt to form a convenient type for all construction works. The total dissolved solids (1.67– 4.53%), gypsum content (0.64–2.13%), organic matters (0.71 – 2.01%), Cl- (0.11 – 0.81%) and pH (7.51 – 7.91) are ranged within the global standards (ASTM, USCS, BS, and IQS). Quartz is predominated mineral, albite and gypsum are of moderate abundance, whereas mica and calcite occurred as traces.

Selection of the number of neurons in different layers of an artificial neural network (ANN) is a key decision-making step involved in its successful training. Although the number of neurons in the input layer is decided by the number of input parameters, and similarly, in the output layer the number of neurons is fixed by the output parameters, however, the number of neurons in the hidden layer is not fixed, whereby the overall efficiency of the ANN depends upon the correct modeling of the realistic scenario in the form of a neural network. Concrete can be mixed in a huge variety of methods and compositions to achieve a specific or a combination of specific results. These results have been observed to repeat and follow patterns. Furthermore, for several types of concrete mixes, only actual physical trial data are available with no mix design method; this makes achieving different required results very complex and expensive task. Having an ANN to be able to predict a concrete mix to handle such variations will save a lot of time and money and will prove to be a universal mix design tool. A thorough analysis for deciding the number of neurons for mix design of concrete has been carried out in this research. The results of neural networks for a varying number of neurons and layers have been correlated. The data for a number of concrete mixes were sorted and normalized. Properties of concrete constituents like specific gravity of cement, coarse and fine aggregates, dry density of coarse and fine aggregates, cement type, type of mineral admixture, water-to-cement ratio, type and temperature of curing and hardened properties like compressive strength, modulus of elasticity and tensile strength were taken as input parameters. The contents of constituents of concrete such as water content, cement content, coarse aggregates content, fine aggregates content and content of mineral admixtures are regarded as output parameters. For 17 inputs and 5 outputs, it has been discovered that simple neural network with single or double hidden layers performed better that 3 or more such layers.

Self-compacting concrete (SCC) has gained huge attention recently due to its high workability which eliminates the need for vibration and makes its placement easier compared to conventional concrete. However, the production of Portland cement (PC) which is the main binder in SCC is energy-intensive and one of the major contributors to the world’s carbon dioxide emission. On the other hand, the use of alkali-activated binders (AABs) in concrete has been reported to reduce the energy consumption and carbon emission of concrete by more than 50%. Therefore, the use of AAB as a binder in SCC can help to achieve an eco-friendlier concrete. This paper gives a short overview of the performance of SCC made with AABs. The effect of various factors on the performance of alkali-activated self-compacting concrete (AASCC) was discussed and a simplified sustainability assessment of AASCC was carried out. Discussions from this paper showed that AASCC with acceptable fresh and hardened properties can be achieved with the proper selection of materials. In addition, the evaluation of the embodied energy and carbon of different types of concrete showed that AASCC is more sustainable. However, more research in this field is required to encourage its universal acceptance and large-scale application.

This paper presents the influence of fly ash properties on angular fly ash aggregate (AFAA) and its manufacturing process to be used as a replacement of natural aggregate in concrete. Characteristics of fly ash play an important role in quality of AFAA as fly ash is the major constituent of the raw materials that are used in manufacturing of AFAA. Ample of studies have already been done on production and utilization of round fly ash aggregate (FAA) by pelletization process, but this study deals with innovative work of manufacturing of AFAA by crushing sintered briquettes into required sizes. Unlike round fly ash aggregate, AFAA possesses rough surface that enhance interlocking of these aggregate with paste in concrete. Four different types of AFAA were manufactured in laboratory by using two different samples of fly ash and two different binders. Performance of AFAA showed that specific surface area and chemical composition of fly ash affects sintering behavior of ash and as a result internal microstructure of aggregate also gets affected. Later, eight types of concrete were produced using four types of manufactured FAA at two different water cement ratio 0.45 and 0.50. It was concluded that strength of concrete depends on properties of manufactured AFAA and nature of bond between cement and aggregate at Interfacial transition zone. AFAA used concrete is found to be lighter in weight compared to the concrete of natural aggregate and is economical for use in construction purposes which in turn can save our depleting natural resources and environmental pollution.

This paper presents the results of experimental program focused on change of compressive strength of concrete exposed to elevated temperature. The change of compressive strength was studied for several types of concrete with different properties (common concrete, air-entrained concrete, concrete with polypropylene fibres, high performance concrete with steel fibres and concrete with basalt fibres). The samples were exposed to high temperatures up to 1000 0C at, the compressive strength was measured at the elevated temperature. This paper presents results of this experiment and comparison of experimental results with available data from literature and valid Eurocodes.

Reinforced concrete structures and structural members used in strategic infrastructures such as highway bridges, high-rise buildings, etc. are inherently subjected to lateral impact loads arising from the collision of vehicles, vessels, falling rocks, and rigid objects having different impact geometries, weights, and velocities. Due to the brittle nature of concrete materials, both localized and overall failure modes are very likely to occur in concrete structures under dynamic and impulsive loads. Hence, many attempts have been carried out in the literature to recognize the failure behaviors and to assess the vulnerability of concrete structure under lateral impact loads. This paper presents a comprehensive state-of-the-art review on the responses and failure behaviors of various types of concrete structures and structural members subjected to lateral impact loads based on analytical, numerical, and experimental studies carried out by the previous research works. In addition, the influences of various structural- and load-related parameters on the impact resistance and failure behaviors of different concrete structures under lateral impact loads are reviewed.

Green concrete is a concept of thinking environment in concrete considering every aspect from row materials manufacture over mixture design to structural design. It has nothing to do with color. The use of various types of recycled waste materials as raw material in cement production is important recent developmental aspect in the field of cement and concrete science is, as well as the use of these materials as aggregate in the production of various types of concrete. Cement and concrete production can consume a substantial percentage of the total generated waste materials, which can alleviate the acute environmental impact of these materials and also partly help to achieve the much needed sustainability in cement and concrete production. The use of waste materials as aggregate in concrete can consume vast amounts of them taking into account the scale of concrete production all over the world as well as the percentage of aggregate in the overall concrete volume

This paper presents the results from the investigation on composite action of reinforced Portland cement concrete and alkali-activated concrete together when subjected to monotonic static loading. The reinforced composite concrete beams consisted of cold joint or two different types of concrete layers. Laboratory test and finite element analysis were carried out for the purpose of evaluation of the behaviour of the beams subjected to static flexural loading. The use of alkali-activated concrete in the beams enhanced the strength capacity and ductility. Such composite action can be employed in case of stage casting of large scale reinforced concrete members. The superior bonding capacity of alkali-activated concrete contributed towards behaviour of Portland cement–alkali-activated concrete beams with cold joints similar to reinforced Portland cement concrete beams. The ageing of substrate did not impart significant effect on the behaviour of the Portland cement–alkali-activated concrete beams with cold joint. Finite element analysis can be successfully employed for predicting the composite action of the Portland cement and alkali-activated concrete beams. However, the use of proper friction coefficient between the different concrete regions and consideration of the effect of concrete substrate ageing is necessary for accurate prediction of the behaviour of the beam with cold joint and various concrete layers.

This research was conducted to investigate the shear strength at the interface between polymer concrete and asphalt concrete with geotextile as reinforcement at the interface of these two types of concrete. The samples were tested for the parameters of different surface conditions [rough and smooth], curing types [room and thermal curing], temperature effect and the impact of geotextile as reinforcement. To investigate the correlation between these parameters, four different testing conditions were implemented. The results showed a significant improvement of shear strength for rough surface sample as compared to smooth surface sample. Moreover, samples cured in oven had lower shear strength as compared to samples cured in room condition. Besides that, high temperature has an adverse impact on the shear strength at the interface between polymer concrete and asphalt concrete due to the weakening of asphalt concrete at high temperature. As for samples reinforced with geotextile, the shear strength resistance was better as compared to unreinforced samples. Through visual observation, the types of failure under all testing conditions were mixed failure mode.

The use of concrete overlays has long been recognised as a cost-effective pavement maintenance and rehabilitation strategy. However, the long-term performance of various types of concrete overlays ...

This study focuses on the durability of concrete reinforced with alfa fibres against external sulphatic attack and thermal stresses. Several mix design and tests were made of three types of concrete reinforced with alfa fibres (AC-0.1, AC-1 and AC-1.5; respectively, 0.1%, 1%, 1.5% of alfa fibres in volume), as well as two control concretes: ordinary concrete (OC) and polypropylene fibre-reinforced concrete (PC). To study the external sulphatic attack, the different types of concrete underwent two ageing protocols: complete or total immersion, and immersion/drying at 60 °C as an accelerated ageing protocol in a Na2SO4 solution with a concentration of 12.5% by weight. For the exposure of the various concretes to thermal stresses, three temperature levels were used. The results showed that the concrete reinforced with 1% of alfa fibres is the most optimal compared to the control concrete, and could enable to produce green and durable structural concretes based on untreated alfa fibres.

Nanotechnology is a blooming field in civil and construction industries. Understanding the role of nanomaterials in strength enhancement and other repair mechanisms is still challenging. With the advancement of nanoscience and nanotechnology, researchers all over the world are focusing on executing its full potential in the development of smart civil structures. Although several studies have been reported on nanoengineered concrete and nanocoatings, their scale-up studies and practical applications is still in nascent stages. This chapter summarizes the latest developments and the future potential of nanomaterials in buildings and other construction materials. Firstly, the general causes and types of concrete defects are elaborated. Then, it focuses on the most effective repair mechanism, microbial-induced carbonate precipitation, and use of nanomaterials that readily enhance self-healing ability and concrete properties. Nanomaterials such as nanosilica, nanoclay, titanium dioxide, nanoiron oxide, alumina, silver, copper, zinc oxide, carbon nanotubes, and graphene oxide/platelets have been reviewed. Finally, challenges, prospects, and implications of nanotechnology in the construction industry are discussed.

The most interesting aim of this research is to assess the capability of artificial neural networks (ANN) to predict the post-fire residual stress–strain curve of unconfined plain and fibrous concretes under axial compression. In this study, the experimental variables are volume fractions of flat crimped steel fibers and polypropylene fibers, inclusion of hybrid fibers and temperature of exposure under natural cooling. A total number of 126 cylindrical specimens of different types of concrete were prepared. These specimens were then exposed to the elevated temperatures ranging from room temperature to 800 °C, and the mechanical properties were evaluated. Based on the test results, an ANN model is developed for the prediction of complete residual stress–strain responses of plain and fiber-reinforced concrete at elevated temperatures. The Levenberg–Marquardt (LM) algorithm has been used in the training. The performance parameters MSE and R values were obtained as 2.2944e−03 and 0.9885, respectively. The stress–strain curves of different samples were predicted and compared with the curves which were obtained experimentally. A good match between the predicted and experimentally obtained stress–strain curves can be observed. An equation based on the weights between the artificial neurons and biases of ANN model was also proposed in this study. The proposed ANN model is unified in nature as this single model is capable in predicting the stress–strain curves for all ranges of temperatures and various compositions of added fibers.

The chapter provides an in depth method with examples on how to calculate the capacity of columns or walls using layers of different types of concrete. The force in a column can be guided via a strong concrete, while a lighter concrete stabilizes the strong against buckling. Columns with Entasis are used as well.

The large temperature difference condition in Northwest China threatens a myriad of concrete structures during construction, with the daily temperature varying by around 40 °C. To investigate the macro-mechanical properties and microstructural characteristics of concrete containing different amounts of mineral admixtures under such harsh conditions, this investigation used an environmental chamber to simulate a saline soil erosion environment with a large temperature difference. Four types of concrete containing different proportions of fly ash and slag were prepared and exposed in the environmental chamber with a daily temperature change of −5~40 °C to investigate their compressive strength, flexural strength, and fracture properties. Moreover, the X-ray diffraction (XRD) characteristics, microscopic morphological characteristics, pore structure characteristics, and post-erosion chloride ion distribution characteristics were also observed and recorded. Results showed that the mineral admixture could improve the early strength development of the concrete and effectively improve the fracture performance of the concrete. The average compressive strength growth rate of concrete from day 3 to day 14 was 83.25% higher than that of ordinary concrete (OC) when 15% fly ash and 15% slag were added. In addition, the fracture energy of the concrete was maximized when 15% fly ash and 20% slag were added, which was 50.67% higher than that of OC, furthermore, the internal compactness and pore structure were optimized, and the resistance to saline soil erosion was strong. This provides a basis for the practical application of compounded mineral admixture-modified concrete in an arid environment with a large temperature difference and saline soil erosion.

Concrete remains the most utilised construction material for building envelopes, which regulate the indoor temperature to achieve human thermal comfort. Often, the energy consumption for building performance appraisal is related to the thermal behaviour of building materials as heating, ventilation, and air conditioning systems all variously contribute to human comfort. Following the development of concrete technology, many types of concrete have been invented to serve several purposes in the construction industry. To clearly understand the concrete type tailored for the specifics of a construction project, the local climate, concrete mechanical properties, and concrete thermal behaviours should be primarily identified to achieve energy efficiency, which also suits the sustainability of global materials. This paper, therefore, reviews the modified concrete thermal behaviours in the tropical climate for more systematic city planning in order to achieve better energy efficiency. Urban heat islands in the tropics and contributing factors, as well as heat transfer mechanisms, are first highlighted. The requirements of concrete thermal behaviour for building envelopes are then discussed through specific heat capacity, thermal conductivity, thermal diffusivity, time lag, and decrement factor in the context of applications and energy consumption in the tropical regions. With a case study, it is found that concrete thermal behaviours directly affect the energy consumption attributed mainly to the use of cooling systems in the tropics. The study can be a reference to mitigating the urban heat island phenomenon in the planning of urban development.

Microbially influenced concrete corrosion (MICC) in sewers is caused by the activity of sulfide-oxidizing microorganisms (SOMs) on concrete surfaces, which greatly deteriorates the integrity of sewers. Surface treatment of corroded concrete by spraying chemicals is a low-cost and non-intrusive strategy. This study systematically evaluated the spray of nitrite solution in corrosion mitigation and re-establishment in a real sewer manhole. Two types of concrete were exposed at three heights within the sewer manhole for 21 months. Nitrite spray was applied at the 6th month for half of the coupons which had developed active corrosion. The corrosion development was monitored by measuring the surface pH, corrosion product composition, sulfide uptake rate, concrete corrosion loss, and the microbial community on the corrosion layer. Free nitrous acid (FNA, i.e. HNO2), formed by spraying a nitrite solution on acidic corrosion surfaces, was shown to inhibit the activity of SOMs. The nitrite spray reduced the corrosion loss of concrete at all heights by 40–90% for six months. The sulfide uptake rate of sprayed coupons was also reduced by about 35%, leading to 1–2 units higher surface pH, comparing to the control coupons. The microbial community analysis revealed a reduced abundance of SOMs on nitrite sprayed coupons. The long-term monitoring also showed that the corrosion mitigation effect became negligible in 15 months after the spray. The results consistently demonstrated the effectiveness of nitrite spray on the MICC mitigation and identified the re-application frequencies for full scale applications.