Prannoy Suraneni

University of Miami | UM · Department of Civil, Architectural, and Environmental Engineering

ASTM C618 and AASHTO M 295 specifications for fly ash represent the primary documents used by U.S. state and federal agencies to determine the suitability of a fly ash source for use in concrete. Other countries have broadly similar specifications for fly ash. The article compares specifications from the United States, Canada, Europe, Australia, an...

The ASTM C311 strength activity index test is a potentially flawed test because inert materials are known to be able to pass the test. The early age of testing, low fly ash replacement levels, variable water-to-cementitious materials ratio, and low strength limits all contribute to the inability of the test to successfully distinguish inert and rea...

Increasing frequency of extreme weather events, driven by climate change, has resulted in an increasing demand for coastal structures to protect and stabilize shorelines. Concrete seawalls are a common category of coastal protection structures, designed with the primary objectives of absorbing wave action, preventing coastline erosion, and alleviat...

Two mine tailings were evaluated for their potential as supplementary cementitious materials. The mine tailings were milled using two different methods-ball milling for 30 minutes and disc milling for durations ranging from 1 to 15 minutes. The modified R 3 test was carried out on the mine tailings to quantify their reactivity. The reactivity of th...

Pavement damage occurs in cold-region concrete exposed to high concentrations of calcium chloride (CaCl2). The damage is caused by a combination of conventional freeze-thaw damage and the formation of a deleterious phase known as calcium oxychloride from a reaction between CaCl2 and calcium hydroxide in the concrete. Much research has focused on ca...

The dissolution kinetics of metakaolin are examined at room temperature in NaOH solutions at concentrations of (0.1, 5, or 10) mol L−1 and at liquid-to-solid mass ratios (L/S) of 50 or 1000. Both the dissolved Si and Al concentrations as well as the morphology and structure of the solid are reported at various times. The dissolution rate is approxi...

Massive amounts of quarry fines are available worldwide. These materials are generally inert, thus limiting their applications. At the same time, shortfalls in conventional supplementary cementitious materials (SCMs) have become an increasing challenge. We can extend SCM usage and reduce filler landfilling by blending these materials together. This...

The concrete industry faces an urgent need to identify new supplementary cementitious material (SCM) sources. One class of materials available in large volumes are basaltic materials, which are often stockpiled in landfills as a waste product from quarries and granule operations. Reactivity testing on some such materials has shown them to be inert....

Calcium aluminosilicate (CAS) glasses are ubiquitous in nature and play an important role in diverse technological applications ranging from structural glasses to sustainable cementitious materials. Understanding the relationship between the chemical composition and the structure of CAS glasses is an essential step towards optimizing their properti...

Supplementary cementitious materials (SCMs) are known to reduce calcium oxychloride (CAOXY) contents in cementitious pastes. However, when availability or cost precludes the use of traditional SCMs, such as fly ash, mitigation could be provided through alternative materials. Fly ash (FA), rice husk ash (RHA), bottom ash (BA), limestone filler (LS),...

Newly developed reactivity tests for supplementary cementitious materials have shown the ability to quantify reactivity and to differentiate reactive and inert materials. Recent results using the modified R3 test are summarized here. The test uses a model system of supplementary cementitious materials mixed with calcium hydroxide in a simulated por...

Modification of fineness, including by grinding or classification, is a commonly used beneficiation method for improving fly ash performance. In this study, five fly ashes, including off-spec and reclaimed ashes, were size fractionated by sieving into the following fractions: < 20 µm, < 45 µm, and > 45 µm. The original fly ash and the size fraction...

Given the dwindling supply of traditional sources, the quest for discovering innovative and sustainable Supplementary Cementitious Materials (SCMs) - potential alternatives to Portland cement (PC) - is now more pressing than ever. Our ability to predict SCM reactivity, let alone optimize it, remains limited by our poor understanding of the basic m...

Steel slag (SS) is a secondary material from steelmaking production with little commercial value. Its volumetric expansion and low reactivity limit the use of SS in Portland cement (PC)- based materials. This study investigated the potential use of basic oxygen furnace (BOF) slag as a single precursor in alkali-activated matrices (AAMs). Six AAM pa...

It is well-accepted that supplementary cementitious materials (SCMs) are the most scalable way of reducing cement-driven carbon dioxide emissions of concrete. Because of changing industrialization trends, production of conventional SCMs such as fly ash and slag have been reduced in many locations to a point at which supply often does not meet deman...

In this study, we evaluate whether thermogravimetric analysis (TGA) can be used to estimate the amounts of collagen and hydroxyapatite in archaeological bone accurately and rapidly, through evaluation of twenty-four previously analyzed archaeological human bone samples. Mass losses in the approximate ranges of 300–500 °C, 220–600 °C, and 600–900 °C...

The feasibility of using a muffle furnace and a balance to determine the calcium hydroxide (Ca(OH)2) consumption of supplementary cementitious materials (SCMs) in model systems was investigated. SCMs were mixed with Ca(OH)2 in an alkaline solution and, after mixing, the paste was sealed inside a 50 °C oven for curing until testing. The chemically b...

Reactivity information for a range of unconventional fly ashes is unavailable in literature. The objective of this study is to quantify the reactivity of numerous unconventional fly ashes using the R3 test (ASTM C1897-20, Standard Test Methods for Measuring the Reactivity of Supplementary Cementitious Materials by Isothermal Calorimetry and Bound W...

Relationships between supplementary cementitious material (SCM) pozzolanic reactivity, bulk electrical resistivity, and alkali-silica reaction expansion were examined for traditional and non-traditional SCMs using the modified R³ test, bulk resistivity measurements, and the accelerated mortar-bar test (AMBT), respectively. The SCMs included pozzola...

In cold regions, calcium and magnesium chloride deicing salts damage concrete pavements due to the formation of certain deleterious chemical phases, including calcium oxychloride. While there is much research at a cement paste-scale, damage in concrete has been less studied. In this study, we evaluate concrete damage due to calcium and magnesium ch...

By the year 2050, glass fiber reinforced polymer (GFRP) material from decommissioned wind turbine blades is expected to generate 40 million tons of waste worldwide. Managing GFRP waste is a vexing problem since the materials cannot be easily recycled. One potential waste management solution is to use the glass fiber (GF) component of GFRP as a supp...

The influence of supplementary cementitious materials (SCMs) and filler fineness on their reactivity in model systems and in cementitious pastes was evaluated. Two SCMs–pumice (P), and glass powder (GP), and an inert filler–limestone (LS), with three different levels of fineness and median particle size (d50) values were tested using the modified R...

As the supply-demand disparity of virgin fly ash increases, there is an urgent need for utilization of unconventional fly ashes. This paper characterizes a set of 19 different fly ashes, including marginal, off-spec, landfilled, or beneficiated materials using extensive physicochemical powder characterization. The chemical composition, mineralogica...

Increasing frequency of extreme weather events, driven by climate change, coupled with growing population densities, have contributed to an increasing demand for coastal structures to protect and stabilize shorelines. Concrete seawalls are a common category of coastal protection structures, designed with the primary objectives of absorbing wave act...

The formation of calcium oxychloride in cold conditions due to a reaction between calcium chloride deicing salt and calcium hydroxide in the concrete causes substantial damage to pavement concretes. In this study, the role of supplementary cementitious materials (SCMs) in mitigating damage in cement pastes and mortars exposed to highly concentrated...

A review of the last 16 years of research (2005–2021) on seawater-mixed concrete is presented. A very significant amount of research, both fundamental and applied, has been performed on this topic, and there is worldwide interest in the use of seawater-mixed concrete to reduce concrete freshwater consumption. Seawater-mixed concrete should be used...

Calcium oxychloride is a serious deterioration mechanism affecting concrete pavements. In order to mitigate calcium oxychloride deterioration in concrete, fly ash is used as partial cement replacement in conjunction with entrained air. Concrete specimens were stored in a 30% calcium chloride solution at 5 °C for 202 days. Following storage, specime...

This paper provides a comprehensive review of the utilization of industrial wastes in 3D concrete printing processes. Concrete 3D printing processes are introduced, highlighting the need for unique material requirements. The literature on the different wastes that have been used for producing 3D printable mixtures is reviewed, including waste gener...

This work characterizes the reaction kinetics of supplementary cementitious materials (SCMs) with calcium hydroxide in the modified R³ test. The heat flow curves of 58 SCMs of varying reactivities were studied. Based on the heat flow curves, the SCMs were classified as more reactive, less reactive, and inert. Most of the heat flow curves in the mod...

Identification and rapid characterization of novel supplementary cementitious materials (SCMs) is a critical need, driven by shortfalls in conventional SCMs. In this study, we present a discussion of recently developed reactivity tests-the R3 test, the modified R3 test, the lime strength test, and the bulk resistivity index test. These tests measur...

The availability of fly ash for concrete has decreased due to the shutdowns of coal-fired power plants. Alternatives to conventional fly ash are needed to ensure sustainable and durable concrete. In this study, the impacts of numerous unconventional fly ashes – reclaimed, beneficiated off-spec, and marginal fly ashes on early and later-age properti...

Owners and designers are increasingly dealing with infrastructure maintenance to ensure adequate level of performance and functioning required by current standards. Corrosion of reinforcement is one of the major factors that reduces the durability of concrete structures. Fiber reinforced polymers (FRP) have emerged as an effective non-corrosive alt...

Calcium oxychloride (CAOXY) formation is a deterioration mechanism known to cause joint damage in concrete pavements. The accepted CAOXY mitigation threshold in paste is 15 g/100 g paste; however, this limit was developed using flexural strength testing of pastes. This investigation seeks to verify this threshold using compressive strength and mass...

Chloride-based deicers, especially CaCl2 and MgCl2, can damage cementitious materials due to the formation of mineral phases such as calcium oxychloride and brucite. However, there are only limited direct observations of calcium oxychloride formed in cementitious materials in the field. This paper uses petrographic methods to evaluate damage of an...

Pavement damage occurs in cold-region concrete exposed to high concentrations of calcium chloride (CaCl2). The damage is caused by a combination of conventional freeze-thaw damage and the formation of a deleterious phase known as calcium oxychloride from a reaction between CaCl2 and calcium hydroxide in the concrete. Much research has focused on ca...

Although calcium oxychloride (Ca-Oxy) is known to damage cementitious materials exposed to calcium chloride (CaCl 2 ) deicers, there is little direct observation of Ca-Oxy in the field due to its instability. This paper uses optical microscopy (OM) and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX) to detec...

Although calcium oxychloride (Ca-Oxy) is known to damage cementitious materials exposed to calcium chloride (CaCl 2 ) deicers, there is little direct observation of Ca-Oxy in the field due to its instability. This paper uses optical microscopy (OM) and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX) to detec...

Concrete and glass fiber reinforced polymer (GFRP) bar samples from an 18-year old repair project executed on an existing dry-dock were obtained by coring the dry dock in two regions. Several destructive and non-destructive tests were performed on both materials. Testing performed on the concrete showed substantial variability and clear evidence of...

For geopolymers (usually composed of unreacted precursor and gel), the compressive strength is controlled by two factors. The first is the degree of reaction, or, equivalently, the amount of gel formed, including any calcium silicate hydrate gel in calcium-containing mixtures. The second factor is the gel composition, generally given by the Si/Al r...

Thermodynamic models for the hydration of ordinary portland cement (OPC) typically predict the composition of the resulting pore solution and the hydrates well. However, predictions for cementitious systems containing OPC and supplementary cementitious materials (SCM) are more challenging. The bulk chemical composition of fly ash does not sufficien...

Mixing municipal solid waste incineration fly ash (MSWIFA) with industrial by-products such as ground granulated blast furnace slag (GGBFS) and ladle furnace slag (LFS) can lead to a hardened system which can encapsulate the heavy metals present in the MSWIFA. The objective of this study is to find optimal mixture designs to effectively encapsulate...

Increasing costs due to failure and reconstruction highlight the importance of concrete durability research. Carbonation of concrete, which can accelerate corrosion, is one of the major deterioration mechanisms in reinforced concrete structures. Experimental data has been used to develop carbonation prediction models, however, the service life pred...

Lunar regolith simulant – JSC-1A is a basaltic powder compositionally similar to rock samples brought back from the moon by Apollo missions. This study describes JSC-1A as a potential construction material advancing the critical, prerequisite knowledge for the construction of shelters on the moon. A reactivity test based on isothermal calorimetry a...

Recently developed reactivity tests for supplementary cementitious materials (SCMs) have shown the ability to differentiate inert and reactive material. Two promising SCM reactivity tests were used to study ten different SCMs. The first method involves quantifying the heat release, bound water, and calcium hydroxide consumption of SCMs in a simulat...

Concrete structures are economical and typically durable when exposed to a variety of environmental conditions. However, carbonation results in a reduction of the durability of reinforced concrete members because it damages the passive film surrounding the reinforcement, which accelerates corrosion processes and may ultimately lead to premature fai...

In this work, the negative impacts of calcium sulfoaluminate (CSA) cement prehydration on hydration and strength gain are investigated. CSA cement in three different states – virgin, prehydrated, and prehydrated and sieved were tested. Cement paste mixtures were made with three levels of ordinary portland cement (OPC) – 0%, 30%, and 70% (indicating...

Modified R³ testing has been used to classify four different SCMs, namely, limestone, pumice, slag, and densified silica fume. Cementitious pastes were prepared by replacing ordinary portland cement with SCMs at different replacement levels – 20%, 40%, and 60% for limestone, pumice, and slag and 5%, 10%, and 15% for silica fume. The influences of S...

This paper investigates the feasibility of using corn stover ash (CSA) as supplementary cementitious material to replace cement in concrete. Three types of CSA -- water-washed, acid-washed, and untreated burned corn stover -- and the influence of the pretreatment regimens on CSA physical and chemical properties are evaluated. The influence of CSA o...

This paper proposes an approach to estimate reaction kinetics for major fly ash glassy oxides in cementitious mixtures. The approach is compared to experimental results from multiple independent datasets. The kinetic model is based on the rate limiting step for various oxides and phases using the general form of a widely used model for ordinary por...

Deicing salts have long been known to cause deterioration in concrete pavements. Freeze/thaw, surface scaling, and reinforcement corrosion are well documented deterioration mechanisms. However, another mechanism exists causing severe concrete damage that is much less understood. This deterioration is due to the formation of calcium oxychloride, fro...

The effect of seawater used as mixing water in concrete on the long-term properties of glass fiber–reinforced polymer (GFRP) bars is the focus of this work. The durability of GFRP bars embedded in seawater-mixed concrete was studied in terms of residual mechanical properties (i.e., tensile strength, horizontal and transverse shear strength, and GFR...

Combining seawater, recycled coarse aggregate (RCA), and glass fiber reinforced polymer (GFRP) reinforcement in structural concrete is potentially advantageous from a sustainability perspective. This paper reports the results of an experimental study on the short-term flexural performance of seawater-mixed recycled-aggregate concrete beams reinforc...

This is an award winning poster which was presented at the 2020 Graduate + Postdoctoral Research Symposium organized by University of Miami on March 5, 2020. Poster briefly explains how the concrete pavements are damaged in cold regions as a result of freeze-thaw cycles and applying deicing salts to prevent water from freezing for safety concerns....

Reinforced concrete tanks in water/wastewater treatment plants are susceptible to severe corrosion due to aggressive exposure conditions resulting from the application of certain treatment chemicals and methods. Non-corrosive materials, such as stainless steel or fiber reinforced polymer (FRP), may be attractive alternative reinforcement options fo...

The use of seawater and recycled coarse aggregate (RCA) in concrete mixtures leads to the production of a very sustainable concrete. The potential risk of steel reinforcement corrosion (due to chloride in the seawater) in such mixtures may be eliminated when considering plain concrete or non-corrosive reinforcement (e.g., fiber reinforced polymer)....

Increased shrinkage is often noted as a concern for alkali activated materials. In this study, two slag-fly ash paste and mortar mixtures with slag:fly ash ratios of 30:70 and 50:50 activated using 4M sodium hydroxide are formulated. The effects of two dosages of a commercial superabsorbent polymer (SAP) on the reaction heat, strength gain, autogen...

Dear Colleagues, Within an increasing global population, especially in cities, the demand for construction and building materials has also increased significantly. This increase has in turn resulted in a significant growth in the utilization of natural resources. Ordinary Portland cement (OPC) is typically the material used in the greatest amount...

The properties of cementitious materials depend on the proportions of unhydrated phases, hydrated phases, and pore volumes in the paste. The Powers-Brownyard model (PB model) has been used to estimate these volumes for ordinary portland cement (OPC) as a function of degree of hydration. However, the PB model was not developed for systems containing...

Chloride binding is typically studied by exposing a certain quantity of powdered hydrated cement paste to chloride salt solutions, and by comparing the differences in final and initial chloride concentrations after equilibrium is achieved. Chloride concentrations are generally determined by titrating the solutions using manual or automatic titratio...

Laboratories typically adapt ASTM C305-14,Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency, ASTM C1738-19, Standard Practice for High-Shear Mixing of Hydraulic Cement Pastes, and other standardized mixing methods to prepare cement paste and mortar specimens for testing. Hand mixing is adapted whe...

The process of desalination results in the production of a hypersaline waste by-product known as reject brine. In some locations, this reject brine is dumped back into the ocean, which has potentially detrimental effects on water quality and marine life. This study was carried out to investigate whether this brine could potentially be used to manuf...

In this study, we show the results of reactivity testing for a large variety of supplementary cementitious materials (SCMs) and fillers. The reactivity test is performed by measuring the heat release (using isothermal calorimetry) and calcium hydroxide consumption (using thermogravimetric analysis) of SCMs mixed with calcium hydroxide (3:1 ratio of...

Distress has recently been observed in the joints of some concrete pavements, primarily in the wet-freeze states. This distress often begins in longitudinal joints, followed by transverse joints and results in the significant loss of material from the joint area. Although it may only affect approximately 10% of the concrete pavements system-wide, i...

Unreinforced concrete or concrete reinforced with non-corrosive reinforcement could potentially be mixed with seawater in locations where potable water is scarce. A fundamental understanding of the properties of concrete mixed with seawater is therefore essential. This paper analyzes the hydration kinetics, hydrate phases, pore solution, and porosi...

Tests to determine the reactivity of supplementary cementitious materials (SCMs) by using isothermal calorimetry and thermogravimetric analysis have been proposed. In one such test, the heat release and calcium hydroxide consumption of SCMs mixed with calcium hydroxide (3:1 ratio of calcium hydroxide and SCM) at 50 C in a 0.5 M potassium hydroxide...

Recently, seawater has emerged as viable mixing water for concrete, especially in the case of non-reinforced concrete applications or with the use of non-corrosive reinforcement. Previous studies concerning seawater-mixed concrete mostly revealed an initial slight increase in its strength performance (i.e., till Day 14 following mixing), followed b...

Given the increasing global concern of freshwater scarcity, the use of seawater in concrete mixtures appears to be a way forward towards achieving sustainable concrete, especially in the case of non-reinforced concrete applications or with the use of non-corrosive reinforcement. This paper reports on the results of an experimental study to compare...

Advancements in service-life prediction of concrete in freeze-thaw environments are reviewed to help inform concrete design, specification, and future areas of research. Critical degree of saturation and the formation of calcium oxychloride are specifically reviewed due to recent research progress and the ability to model the service-life of concre...

Municipal solid waste incineration fly ash (MSWIFA) is a hazardous by-product of waste incineration. The objective of this research is to encapsulate the chloride in MSWIFA and to develop a utilizable construction material using MSWIFA, ground granulated blast-furnace slag (GGBFS), ladle furnace slag (LFS), and gypsum. A secondary objective of the...

This paper examines factors that influence temperature corrections in the electrical resistivity measurements of concrete. The Arrhenius equation is used to describe the electrical resistivity as a function of temperature using an activation energy of conduction (E a-cond). This parameter has been measured on a wide variety of materials including p...

A pozzolanic test that can correctly identify pozzolanic materials is key in the search for alternative supplementary cementitious material (SCMs). Determination of the degree of reaction of these alternative SCMs in cementitious pastes is also important, as the reactivity of certain SCMs can be quite low. Since typical methods to determine SCM deg...

Limited applications for the large amounts of steel slags produced globally exist. In this study, the hydraulic and pozzolanic behavior of basic oxygen furnace slag (BOFS) and ladle furnace slag (LFS) are studied and contrasted with the behavior of ground granulated blast furnace slag (GGBFS). Pozzolanic test, isothermal calorimetry, thermogravimet...

The shrinkage behavior of cementitious materials mixed with seawater is investigated. Cement mortar mixtures were prepared with two water-to-cementitious materials ratios (w/cm = 0.36 and 0.45), two binder compositions (namely, ordinary Portland cement (OPC) and OPC with 20 % fly ash replacement), and two types of water (tap water and seawater). Th...

Ionic transport in concrete can be described using the formation factor. The formation factor is computed as the ratio of the resistivity of the bulk concrete to the resistivity of the pore solution. As such, calculation of the formation factor requires knowledge of pore solution resistivity. The objective of this study is to use X-ray fluorescence...

In cementitious materials exposed to solutions containing chloride, chloride binding typically results from the chemical reactions between chloride ions and aluminate phases to form Friedel’s salt, and the interaction between chloride ions and calcium silicate hydrates (C-S-H). Calcium oxychloride can also form when Ca(OH)2 in cementitious material...

Using seawater for mixing concrete is potentially advantageous from a sustainability perspective. However, the presence of high concentrations of chloride in the seawater can lead to corrosion of steel reinforcement. This issue can be addressed by using non-corrosive reinforcement; e.g., fiber reinforced polymer (FRP) bars. Moreover, the global thr...

A thermodynamic modeling-based Monte Carlo analysis was conducted to investigate the effect of supplementary cementitious material (SCM) replacement level and reactivity on chemical binding of admixed chlorides and pore solution composition in ordinary portland cement (OPC) + SCM systems. Specifically, the validity of using total cementitious mater...

Blast furnace slag (SL) is an amorphous calcium aluminosilicate material that exhibits both pozzolanic and latent hydraulic activities. It has been successfully used to reduce the heat of hydration in mass concrete. However, SL currently available in the market generally experiences pre-treatment to increase its reactivity to be closer to that of p...

The goal of this method is to determine the chemical composition and electrical resistivity of cementitious pore solution expressed from a fresh paste sample. The pore solution is expressed from a fresh paste sample using a pressurized nitrogen gas system. The pore solution is then immediately transferred to a syringe to minimize evaporation and ca...

Premature deterioration has been observed at some joints in concrete pavements. This joint damage has been attributed, in part, to a deleterious chemical reaction between chloride-based deicing salts (e.g., calcium chloride) and calcium hydroxide from the cementitious matrix resulting in the formation of a compound referred to as calcium oxychlorid...

Magnesium chloride (MgCl2) reacts with cement pastes resulting in calcium leaching and the formation of calcium oxychloride, which can cause damage. This paper examines the damage in different cement pastes exposed to MgCl2 solutions. Volume change measurement and low temperature differential scanning calorimetry are used to characterize the format...

Friedel’s salt forms in cementitious materials exposed to NaCl solutions. This paper quantifies the amount of Friedel’s salt that forms and relates the formation of Friedel’s salt to the damage. Thermogravimetric analysis (TGA) is used to quantify the amount of Friedel’s salt. The volume change associated with the formation of Friedel’s salt is mea...