Cellular sprayed concrete for simple and economic remixing

The development of various supplementary cementitious materials (SCMs) and chemical admixtures, makes the manufacturing of high-performance shotcrete possible. The most important SCM in high-performance shotcrete is silica fume because of its effect on pumpability, high-strength and durability which lies in its Pozzolanic reaction. Furthermore, the very small particle size of silica fume reacts more quickly than other SCMs and acts as a filler which contributes to the nano-sized porosity occurring in the interfacial transition zone. On the other hand, because of the extremely small particle size of silica fume, it is used as a pre-blended type with a Portland cement for a better distribution of silica fume in concrete. This results in a high cost material. If it is possible to distribute the very fine silica fume in a ready-mixed concrete, this would results in a very simple and an economic way. A very innovative method, which was named as Cellular sprayed concrete, was developed. Cellular sprayed concrete is a process to produce a High-Performance Concrete (HPC) by adding cellular and silica fume in ready-mixed concrete. This method enable to distribute the very fine silica fume in a ready-mixed concrete. This paper describe on the very new and innovative concept and procedures of cellular sprayed concrete

Application of cellular sprayed concrete into two-lift concrete

Two-lift concrete paving involves placing two layers of concrete \u27wet-on-wet\u27 instead of the traditional method of using a single homogeneous layer of concrete. The thick bottom layer offers the opportunity to optimize the use of local aggregates, recycled materials to produce an economical, durable, and sustainable pavement system with the most desirable surface characteristics like improved skid resistance and reduced noise provided by the high-quality surface of the high-performance concrete. The time between placing layers is often no more than 30 minutes. Perhaps the challenge involved in the construction of two-layer concrete systems includes the additional costs and logistics required for two plants to produce different concrete mixtures and two slip-form paver for paving both of bottom and top layers. A very simple and economic method for remixing an ordinary Portland cement concrete (OPC) into a high performance concrete (HPC) at a job site was developed, which is called \u27Cellular sprayed concrete\u27. Cellular sprayed concrete is produced by incorporating a preformed foam and fine powders in a ready mixed concrete and is conveyed under pressure through a pneumatic hose or pipe and projected into place at high velocity, with simultaneous compaction. This method can solve the problem of two batch plants and two pavers in 2LCP construction. \u27Cellular sprayed concrete\u27 enable utilizing a single batch plant for constructing 2-lift concrete pavement instead of 2 batch plants. This paper describes an extra ordinary application of sprayed concrete into concrete pavement

Application examples of a very economic way of cellular sprayed concrete on retaining wall and artificial rock

An economic slope structure construction method for landscape was developed, which utilized the cellular sprayed concrete for high performance shotcrete. This can improve the performance of shotcrete material, maximize the construction advantages of shotcrete and further harmonize with the surrounding environment. This may solve various problems such as efficient slope stabilization of large-scale slopes from natural disasters that occur annually due to climate change, the necessity of disaster prevention and restoration technologies, existing slope maintenance and reinforcement construction methods for weathering. This construction method maximizes the economic feasibility by manufacturing a high-performance cellular shotcrete using an ordinary ready mixed concrete and concrete pump car. Cellular shotcrete is produced by incorporating cellular and mineral admixtures in the process of remixing and dispersing the mineral admixture in an ordinary ready mixed concrete at a job site. High strength and high durability are secured by using high-performance cellular shotcrete without using accelerators. Speed and safety are improved by adopting a concrete pump car reaching a far way on the slope without formwork in the top-down and bottom-up method. In addition, this technique can highlight nature-friendly scenery since it is a construction method that comprehends natural rock shapes and colors, by carving various natural rock patterns on the placed high-performance shotcrete before the thickness is adjusted and before it hardens. After curing for a certain period of time, a coloring agent like stain is sprayed on the surface to develop color by neutralization reaction

Predicting Pumpability and Shootability of Crushed Aggregate Wet-Mix Shotcrete Based on Rheological Properties

This study aims to estimate the pumpability and shootability of wet-mix shotcrete (WMS) made with crushed aggregates and various admixtures such as silica fume, fly ash, ground granulated blast furnace slag (GGBFS), metakaolin, and steel fiber based on rheological properties. The IBB rheometer was employed as an apparatus to measure the rheological properties of freshly mixed shotcrete such as flow resistance and torque viscosity. Results have shown that the use of silica fume and metakaolin led to satisfactory pumpability, whereas mixtures with fly ash and steel fiber failed to meet the pumping criteria at normal pump pressure. The build-up thickness, an indicator to represent shotcrete shootability, was predicted to vary between 68 and 218 mm, demonstrating that the use of admixtures resulted in a wide spectrum of shootability. In particular, the use of metakaolin was found to substantially increase the predicted build-up thickness only with a small replacement. The findings of this study are expected to be used as an easy-to-use guideline for estimating pumpability and shootability of WMS when no compliance testing data is available

Differential Proteome Profiling Using iTRAQ in Microalbuminuric and Normoalbuminuric Type 2 Diabetic Patients

Diabetic nephropathy (DN) is a long-term complication of diabetes mellitus that leads to end-stage renal disease. Microalbuminuria is used for the early detection of diabetic renal damage, but such levels do not reflect the state of incipient DN precisely in type 2 diabetic patients because microalbuminuria develops in other diseases, necessitating more accurate biomarkers that detect incipient DN. Isobaric tags for relative and absolute quantification (iTRAQ) were used to identify urinary proteins that were differentially excreted in normoalbuminuric and microalbuminuric patients with type 2 diabetes where 710 and 196 proteins were identified and quantified, respectively. Some candidates were confirmed by 2-DE analysis, or validated by Western blot and multiple reaction monitoring (MRM). Specifically, some differentially expressed proteins were verified by MRM in urine from normoalbuminuric and microalbuminuric patients with type 2 diabetes, wherein alpha-1-antitrypsin, alpha-1-acid glycoprotein 1, and prostate stem cell antigen had excellent AUC values (0.849, 0.873, and 0.825, resp.). Moreover, we performed a multiplex assay using these biomarker candidates, resulting in a merged AUC value of 0.921. Although the differentially expressed proteins in this iTRAQ study require further validation in larger and categorized sample groups, they constitute baseline data on preliminary biomarker candidates that can be used to discover novel biomarkers for incipient DN

Rheological Behavior of High-Performance Shotcrete Mixtures Containing Colloidal Silica and Silica Fume Using the Bingham Model

There have been numerous studies on shotcrete based on strength and durability. However, few studies have been conducted on rheological characteristics, which are very important parameters for evaluating the pumpability and shootability of shotcrete. In those studies, silica fume has been generally used as a mineral admixture to simultaneously enhance the strength, durability, pumpability, and shootability of shotcrete. Silica fume is well-known to significantly increase the viscosity of a mixture and to prevent material sliding at the receiving surface when used in shotcrete mixtures. However, the use of silica fume in shotcrete increases the possibility of plastic shrinkage cracking owing to its very high fineness, and further, silica fume increases the cost of manufacturing the shotcrete mixture because of its cost and handling. Colloidal silica is a new material in which nano-silica is dispersed in water, and it could solve the above-mentioned problems. The purpose of this research is to develop high-performance shotcrete with appropriate levels of strength and workability as well as use colloidal silica for normal structures without a tunnel structure. Thereafter, the workability of shotcrete with colloidal silica (2, 3, and 4%) was evaluated with a particle size of 10 nm and silica fume replacement (4 and 7%) of cement. In this study, an air-entraining agent for producing high-performance shotcrete was also used. The rheological properties of fresh shotcrete mixtures were estimated using an ICAR rheometer and the measured rheological parameters such as flow resistance and torque viscosity were correlated with the workability and shootability. More appropriate results will be focusing on the Bingham model properties such that the main focus here is to compare all data using the Bingham model and its performance. The pumpability, shootability, and build-up thickness characteristics were also evaluated for the performance of the shotcrete. This research mainly focuses on the Bingham model for absolute value because it creates an exact linear line in a graphical analysis, which provides more appropriate results for measuring the shotcrete performance rather than ICAR rheometer relative data

Predicting Pumpability and Shootability of Crushed Aggregate Wet-Mix Shotcrete Based on Rheological Properties

This study aims to estimate the pumpability and shootability of wet-mix shotcrete (WMS) made with crushed aggregates and various admixtures such as silica fume, fly ash, ground granulated blast furnace slag (GGBFS), metakaolin, and steel fiber based on rheological properties. The IBB rheometer was employed as an apparatus to measure the rheological properties of freshly mixed shotcrete such as flow resistance and torque viscosity. Results have shown that the use of silica fume and metakaolin led to satisfactory pumpability, whereas mixtures with fly ash and steel fiber failed to meet the pumping criteria at normal pump pressure. The build-up thickness, an indicator to represent shotcrete shootability, was predicted to vary between 68 and 218 mm, demonstrating that the use of admixtures resulted in a wide spectrum of shootability. In particular, the use of metakaolin was found to substantially increase the predicted build-up thickness only with a small replacement. The findings of this study are expected to be used as an easy-to-use guideline for estimating pumpability and shootability of WMS when no compliance testing data is available