Strength Activity Index Test Research Articles

Pozzolanic Reactivity of High-Alkali Supplementary Cementitious Materials and Its Impact on Mitigation of Alkali-Silica Reaction

The growing scarcity of conventional supplementary cementitious materials (SCMs) such as Class F, Class C fly ashes, and slag has necessitated exploring alternative SCMs previously considered suboptimal. In particular, high-alkali SCMs are often avoided because of the potential concern that their alkali content could release into the concrete pore solution, thus exacerbating the potential for alkali-silica reaction (ASR). However, preliminary research indicates that not all high-alkali SCMs are deleterious, and some can effectively suppress the ASR expansive reaction when used in sufficient dosage levels. This study evaluates the feasibility of using high-alkali SCMs, such as high-alkali natural pozzolans and reclaimed fly ashes, focusing on their pozzolanic reactivity and the correlation between the reactivity and their ASR mitigation performance. The pozzolanic reactivity of the SCMs was evaluated by the R3 test per ASTM C1897 and strength activity index test per ASTM C311. Thermogravimetric analysis was used to determine the calcium hydroxide consumption by the SCMs. ASR mitigation performance of SCMs was evaluated in accordance with American Association of State Highway and Transportation Officials (AASHTO) T380 miniature concrete prism test. Additionally, pore solution expression and analysis of paste specimens were conducted to determine the correlation between the total alkali and the released alkali levels into the pore solution. Based on the results of this study, all SCMs indicated high pozzolanic reactivity; however, individual performance varied by test method. Ultimately, the high-alkali SCMs, particularly natural pozzolans, did not appear to release any significant levels of alkalis into the pore solution readily and, therefore, show potential for ASR mitigation when used in sufficient dosage levels.

Pozzolanic reaction and strength activity index of dolomite powder incorporated cement mortar

Assessment of pozzolanic activity of an alternative material is a key parameter for its application as a cementitious material. This study has been conducted to check the scope of dolomite powder in its native and calcined state as a substitute for cement for sustainable construction practices. Dolomite is a variety of limestone consisting of calcium carbonate and magnesium carbonate in predominant compositions. The chemical composition of dolomite powder is determined using X-ray florescence (XRF) technique. XRF test results showed the presence of 31.08 % of Calcium Oxide and 21.3 % of Magnesium Oxide as major compounds in dolomite powder. Frattini and Strength Activity Index (SAI) tests have been conducted to analyze the pozzolanic activity of dolomite powder. Frattini test determines the consumptions of hydroxyl ion (OH–) and calcium ion (Ca+2), which are plotted in the solubility curve to decide the pozzolanic behavior of a material. The test on dolomite powder in its native state resulted in no pozzolanic activity, while in the calcined form, pozzolanic activity was observed. This behaviour was due to the activation of quick lime after the calcination process. The strength Activity Index (SAI) test is conducted to compare the compressive strength of nominal and modified mixes at 7 and 28 days. The dolomite powder in its native state satisfied the Strength Activity Index (SAI) criteria at 7 and 28 days owing to its ultra-fine particle size. The SAI test observations were on the higher side in the calcined state as both – ultra-fine particle size and quick lime contributed to the strength of the mix.

Mineralogical, pozzolanic and microscopic characterization of dolomite mine overburden

Waste generated during the cutting and processing of stones is a severe environmental problem. Using waste materials in civil engineering applications is beneficial for sustainable construction practices. The stone industry generates a very high quantity of overburden during mining processes. This overburden is discarded as its composition is not similar to that in the pure state. This study aims to characterize the dolomite mine overburden in its native state. This characterization is based on mineralogical, pozzolanic and microscopic characteristics of dolomite overburden. The mineralogical characterization was done using XRD and XRF analysis. XRD tests showed the presence of dolomite [CaMg(CO3)2] and Silica Oxide (SiO2) in significant compositions. The predominant presence of 30.54 % of Calcium Oxide (CaO), 18.71 % Silica Oxide (SiO2) and 7.6 % of (MgO) was determined by XRF analysis. Frattini and Strength Activity Index (SAI) tests were performed to check the presence of pozzolanic properties in the material. Frattini test results showed the non-pozzolanic/inert nature of overburden. The inert nature of dolomite overburden was confirmed by SAI test results. The modified mix failed to fulfill the criteria of 75 % and 85 % strength of the control mix after 7 and 28 days of curing. The microscopic analysis was carried out by SEM analysis. SEM images showed the irregular shape and rough surface texture of dolomite overburden. The pozzolanic characterization proves that the dolomite mine overburdened can't be used as a cementitious material. Its application can be tested for filler material or as a replacement for coarse/fine aggregates in concrete and mortar mixes. It can also be tested as filler material in bituminous mixes or stabilizing agent in soil stabilization.

Investigation of the use of ground raw vermiculite as a supplementary cement materials in self-compacting mortars: Comparison with class C fly ash

A significant part of the global CO2 emission comes from the production of Ordinary Portland Cement (OPC). Supplementary cement materials (fly ash, silica fume, blast furnace slag, natural pozzolans, etc.) have been used in concrete and mortar production for decades. Due to the limited resources of these supplementary cementitious materials, there was no significant reduction in CO2 emissions. Therefore, the search for new materials and methods continues. In recent years, the use of clay types such as kaolin, metakaolin and bentonite in mortar has become widespread. However, no information has been found in the literature regarding the use of finely ground raw vermiculite as a supplementary cement material. In this study, the effects of ground raw vermiculite (RV) replaced for cement on self-compacting mortar (SCM) were investigated. In this context, 5%, 10%, 15% and 20% ground RV was used in SCM mixtures. SCM mixes was tested for fresh concrete such as slump-flowing and V-funnel times. The pozzolanic activity of fly ash and ground raw vermiculite have been using the strength activity index test. Prism specimens of 40 × 40 × 160 mm3 were produced in order to determine their mechanical properties. These samples were subjected to the flexural strength test at the end of 7, 28 and 90 days and the compressive strength test was performed on the parts obtained from the flexural test. In addition, the durability properties of SCM mixes such as capillary water absorption, sorptivity and porosity were determined. The fresh concrete, mechanical and durability results of RV replacement mortars were compared with Class C fly ash (FA), which is commonly used in SCM mixtures. The results showed that the presence of 5% RV gives the highest compressive strength value at all ages. The presence of 5% and 10% RV improved the 90 days compressive strength value by 3.68% and 2.91%, respectively, compared to the FA substituted series at the same rate. The lowest sorptivity coefficient of 90 days was calculated in the RV5 series with 0.037 mm/min1/2. The results showed that the presence of ground RV in the range of 10–15% in SCM mixtures did not adversely affect the mechanical and durability properties of the mixtures. However, 20% RV use negatively affected the properties of SCM.

Strength activity index and bulk resistivity index modifications that differentiate inert and reactive materials

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 reactive materials. Test modifications utilizing higher replacement levels (50% by mass) and higher temperatures (50 °C) are evaluated in this study for three fly ashes and two inert materials. Bulk resistivity is also measured in addition to strength. Using higher replacement levels and higher temperatures provides improved differentiation of inert and reactive materials when using strength, however, the magnitude of differences is somewhat small, when considering variability in strength measurements. On the other hand, higher replacements and especially higher temperatures result in a very substantial increase in bulk resistivity for the fly ashes but not for inert materials. Therefore, a bulk resistivity index test carried out at higher temperatures provides for clear differentiation of inert and reactive materials and should considered for standardization/specification. The calcium hydroxide contents and heat release measured in corresponding cement pastes show that increased temperature enhances fly ash reaction but does not affect inert materials. At higher replacement levels, greater effects of fly ash reaction are manifested, resulting in better differentiation from inert materials than at lower replacement levels.

Enhancement of pozzolanic activity of calcined clays by limestone powder addition

The influence of limestone powder addition on pozzolanic reactivity of calcined clays were investigated. Two clays containing kaolinite and halloysite in their compositions were obtained from different deposits in Turkey and physical, mineralogical, and morphological properties of the raw and calcined clay were characterized. Pozzolanic reactivity of calcined clays with and without limestone powder addition was then examined by means of lime consumption in lime-calcined clay pastes and their isothermal calorimetry as well as strength activity index test. Limestone powder addition enhanced the pozzolanic reactivity of calcined clays by increasing lime consumption and presenting higher heat of reaction released during pozzolanic activity. Limestone addition also provided benefits of reduced water requirement and increased strength activity for calcined clays. Improvements in pozzolanic reactivity and strength activity of calcined clays with limestone powder addition were attributed to nucleation effect provided by limestone particles and also formation of carboaluminate phases during pozzolanic reaction.

Influence of Lime and Marble powder Waste on the Strength Activity Index of Self Compacting Mortar and Concrete

Void free mass, congested reinforcement, reduced section, and surface finishes are the present demand in the construction sector that can be fulfilled using Self Compacting Concrete (SCC). It flows under self-weight and develops a homogeneous dense mass of concrete without external energy (Vibration). The research described in this research examined the making of SCC with readily available materials. The most crucial distinction is the presence of filler material and small aggregate size in the SCC mixture. To obtain the benefit of filler material, reduced cement content, improve workability and strength in SCC, two fillers selected from a group of natural inert by-product, limestone powder (LP), and marble powder (MP). For this purpose, mortar cube prepared as per BS 3892 with two fillers, LP and MP by 10%, 15%, and 20% of replacement with a different combination. Present work also investigates the pozzolanic and filler effect of partial replacement in mortars by strength activity index (SAI), also tried to develop the relationship between fresh SCC slump flow and V-flow spread time. The observed value in the SAI test for the sixteen samples of a mineral filler of 10%,15%, and 20% replacement compared with a normal mix, all samples have the value lower than the control mix of 80% as per BS 3892. It is due to the effect of the filler on the microstructure and the presence of superplasticizer. From these results, it is concluded that filler, LP, and MP does not contribute to pozzolanic reaction, and it is still unhydrated at the age of 28 days.

Evaluation of Steel Industrial Slag as Partial Replacement of Cement in Concrete

Cement is the most important ingredient in concrete, which acts as a binding material. It is evaluated that cement is the second largest industrial source of CO2 on earth. This demands a partial or full replacement of cement by an environment-friendly material. In this research industrial waste slag from a local Steel Mill, namely Mangla Metals was selected as possible replacement of cement. Some preliminary standard tests conducted on the slag showed its strong chances to be used as pozzolana. Slag used for this study was reduced to the particle size passing through ASTM standard sieve #100. Concrete specimens containing 10% and 20% replacement of cement by slag were prepared. The mechanical properties like compressive, split cylinder tensile and flexure strength were determined as per standard ASTM methods. Tests were conducted at 3, 7 and 28 days of concrete age. Results show a decrease of 14% in compressive strength, 7.5% in tensile strength and 10.5% in flexure strength for 10% replacement vis-à-vis control specimens at 28 days. For 20% replacement, the decrease in compressive, tensile and flexure strength are 25.5%, 29%, 31% respectively. Additionally, ASTM standard strength activity index test with finer slag particles passing through ASTM sieve #200 provided compressive strength more than that of control specimen. Based on the results, it is concluded that the industrial slag has the potential to partially replace the cement if slag is ground to the particles, passing through ASTM sieve #200. This could lead to a huge reduction of cement quantity in concrete and the environmental burden due to deposition of waste slag in landfills.

Evaluation of Ash Pozzolanic Activity by Means of the Strength Activity Index Test, Frattini Test and DTA/TG Analysis

Evaluation of Ash Pozzolanic Activity by Means of the Strength Activity Index Test, Frattini Test and DTA/TG Analysis

Pozzolanic reaction of sugarcane bagasse ash and its role in controlling alkali silica reaction

Pozzolanic materials are used worldwide to improve concrete properties. In this study, the pozzolanic behavior of sugarcane bagasse ash (SBA) and its role in controlling alkali silica reaction (ASR) was investigated. For this purpose, SBA was acquired from a sugar processing industry. Locally available reactive aggregates were used to introduce the phenomenon of ASR. To evaluate the role of SBA in mitigating ASR, mortar bar specimens were prepared following ASTM C1260 with various SBA dosages (10%, 20%, 30% and 40% by cement weight). To investigate the pozzolanic behavior of SBA strength activity index test and thermal analysis were performed. Results of activity index and thermal analysis showed the pozzolanic behavior of SBA. Moreover, reduction in mortar bar expansion was observed 23% and 46% after replacing 10% and 40% cement with SBA, respectively. Microscopic examination also showed no signs of cracks in mortar bars incorporating SBA; however minor cracking was observed in control specimens due to ASR. Furthermore, Energy disperse X-ray spectroscopy (EDS) showed low Ca/SiO2 ratio of mortar bars incorporating SBA due to dilution process and alkali absorption leading to control the ASR expansion. Therefore, based on the results it can be concluded that pozzolanic behavior of SBA can be helpful in controlling ASR expansion by binding alkalies.

How to evaluate pozzolanic activity of sulfate-rich fly ash

The Frattini test and strength activity index (SAI) test have been commonly used methods to assess the pozzolanic activity of pozzolan by measuring its reaction extent, which would be affected by the sulfate content in pozzolan and the cement used. This study investigates the effect of sulfate content in sulfate-rich fly ash on the test results regarding pozzolanic activity by means of the Frattini test and SAI test; three fly ashes with different sulfate contents are used and their sulfate contents are further increased by adding calcined gypsums. There is significant correlation between the test results of the pozzolanic activity and the sulfur trioxide content of the cement–fly ash system, no matter whether the sulfates came from cement or fly ash. However, current methods may confound the test results regarding the pozzolanic activity of sulfate-rich fly ash. It is suggested that the sulfur trioxide content of the cement–fly ash system should be kept constant when the Frattini test and SAI test are selected to evaluate the pozzolanic activity of sulfate-rich fly ash or to compare with other fly ashes and pozzolans.

The potential of ground clay brick to mitigate Alkali–Silica Reaction in mortar prepared with highly reactive aggregate

The objective of this work was to study the effect of ground clay brick on mitigating the Alkali Silica Reaction (ASR) in mortar bars prepared with highly reactive aggregates. To evaluate the potential of ground crushed clay brick to mitigate ASR distress in mortar, mortar bars and mortar cubes were cast with combination of different dosages of ground clay brick (partial replacement of portland cement). The pozzolanic reactivity of ground clay brick was also evaluated using strength activity index test. In addition, the Scanning Electron Microscopy (SEM) and the Energy-Dispersive X-ray Spectroscopy (EDS) were conducted to evaluate the microstructure and location of the ASR gel and its chemical composition. The results from this study indicated satisfactory level of pozzolanic reactivity when cement was partially replacement by the ground clay brick. Also, it was found that replacing 25% of cement with ground clay brick (by weight) could significantly decrease the ASR expansion by 67% at the age of 14days. However, this study suggested that the compressive strength values of the specimens containing higher dosages of ground crushed brick (i.e. 50% replacement level) were significantly lower than that of the control specimens.

Assesment of Pozzolanic Performance of Sugarcane Bagasse Ash

AbstractSugarcane bagasse ash is obtained as a by-product from cogeneration combustion boilers in sugar industries, and is reported to be a useful supplementary cementitious material in concrete. A clear evaluation of pozzolanic activity of sugarcane bagasse ash is imperative to achieve its effective utilization in concrete instead of being disposed as a waste in enormous quantities. Pozzolanic activity of raw sugarcane bagasse ash and a processed sample of the same was assessed by five different standard methods in this study. The methods used were: strength activity index test, lime reactivity test, Frattini test, electrical conductivity test, and lime saturation test. In addition, chemical and mineralogical analyses were also performed on the bagasse ash. Durability performance of concrete with bagasse ash blended cement was evaluated and compared with fly ash-based concrete. The results from the studies indicate that raw bagasse ash has low pozzolanic activity due to presence of fibrous carbon particl...

Characterization of sugar cane bagasse ash as supplementary material for Portland cement

Sugar Cane Bagasse is a by-product of the sugar agro-industry; it is partly used as fuel. However, bagasse ash (SCBA) is considered waste, which creates a disposal problem. Furthermore, if sugar cane bagasse is burned under controlled conditions, the SCBA can be potentially reused. This paper considers the technical viability of using SCBA as a partial replacement for cement. Two samples of SCBA from a Colombian sugar industry were characterized. The chemical composition of the samples shows high percentages of silica, 76.3% and 63.2%. The mineralogical and morphological characteristics of the waste were determined by X-ray diffraction patterns (XRD), thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The pozzolanic activity of SCBA was evaluated using the Frattini test and the strength activity index test (SAI). The ASTM C618 defines an SAI of at least 75% as a requirement for classifying material as a pozzolan. This condition was achieved in the experiments performed. The results indicate that SCBA produced in the manufacture of commercial cements can be recycled for use as pozzolanic material. This supplementary material can partially replace cement and therefore reduce CO2 emissions.

Assessment of pozzolanic activity of different calcined clays

Abstract The pozzolanic activity of calcined clays depends on the type and amount of clayed minerals, the nature and amount of impurities, the thermal treatment used for its activation and the specific surface obtained after calcination. In this paper, four test methods for assessment the pozzolanic activity on seven calcined clays (five kaolinites and two bentonites) were analyzed. Natural clays were calcined and investigated by two direct tests (Frattini and saturated lime) and two indirect tests (strength activity index and electrical conductivity). Frattini test and the strength activity index (SAI) were found to be the most accurate and reliable methods to assess pozzolanic activity over time. Frattini test evaluates accurately the calcium hydroxide (CH) consumption by pozzolanic reaction, and SAI test discriminates the real contribution of pozzolanic reaction to densification of microstructure. The electrical conductivity (EC) and the lime consumption (LC) tests evaluate the ability of pozzolanic material to fix CH during the first time of contact and their results are correlated with the specific surface of calcined clay.

Comparison of test methods to assess pozzolanic activity

Assessment of the pozzolanic activity of cement replacement materials is increasingly important because of the need for more sustainable cementitious products. The pozzolanic activity of metakaolin , silica fume , coal fly ash, incinerated sewage sludge ash and sand have been compared using the Frattini test, the saturated lime test and the strength activity index test. There was significant correlation between the strength activity index test and the Frattini test results, but the results from these tests did not correlate with the saturated lime test results. The mass ratio of Ca(OH) 2 to test pozzolan is an important parameter. In the Frattini test and strength activity index test the ratio is approximately 1:1, whereas in the saturated lime test the ratio is 0.15:1. This explains why the saturated lime test shows higher removal of Ca(OH) 2 and why the results from this test do not correlate with the other test methods.

Effect of milling and acid washing on the pozzolanic activity of incinerator sewage sludge ash

Incinerator sewage sludge ash (ISSA) is a problematic waste that contains significant levels of phosphates, primarily in the form of whitlockite (Ca3(PO4)2). Phosphate is a valuable finite resource, and a number of studies have shown that it can be extracted from ISSA by acid washing. This produces an acid washed residue that has potential to be used in construction products. The effects of milling and acid washing on the pozzolanic activity of ISSA have been evaluated using the strength activity index (SAI) test and the Frattini test. Coal fly ash (FA), metakaolin (MK) and quartz sand were also tested for comparison. Milling improved the pozzolanic activity of FA and ISSA according to both the SAI and Frattini tests. If ISSA is acid washed to recover phosphate, the process is likely to produce an acid insoluble material with little or no pozzolanic activity. The Frattini test is considered a more suitable method for directly assessing pozzolanic activity as a range of factors can affect SAI test results.

Factors Influencing Flow and Strength of Standard Mortars and Reappraisal of ASTM Test Methods for Fly Ash

Abstract Modified Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use as a Mineral Admixture in Portland-Cement Concrete (ASTM C 311) Pozzolanic (Strength) Activity Index tests with five fly ashes and two portland cements were done to compare results with those of standard tests. When sand contents (at constant water and cement contents) were varied, strengths of 38°C cured mortars decreased (−30 to −50 kPa/g of sand added in mixes containing 1370 to 1570 grams of sand) for different cement/fly ash blends. When water contents (at constant sand contents) were varied, strengths varied (−125 to +190 kPa/mL), strengths tending to increase because of paste volume increases with water content. Flow of mortars in both kinds of tests increase nearly linearly with paste volume fractions; the slopes are related by a factor of 0.60 ± 0.04. Accelerated curing at 38°C for tests at 28 days usually yields higher relative strengths than after curing at 23°C for 91 days. Multiple linear regression equations using both kinds of test data are solved at specified flow and strength values to determine proportions and mortar volume yields. This more general performance test ranks fly ashes (or cementitious mixtures) by mortar volume yield at equal flow and strength, and is suggested as a candidate to replace the present Strength Activity Index test.