Performance of Impure Calcined Clay as a Pozzolan in Concrete

2020 ◽  
pp. 036119812095314
Author(s):  
Khashayar Jafari ◽  
Farshad Rajabipour
Keyword(s):  
Portland Cement ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Natural Pozzolan ◽  
Quartz Content ◽  
Calcined Clay ◽  
Air Content ◽  
Sand And Gravel

Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.

Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

2021 ◽  
Vol 1036 ◽  
pp. 240-246
Author(s):  
Jin Tang ◽  
Su Hua Ma ◽  
Wei Feng Li ◽  
Hui Yang ◽  
Xiao Dong Shen
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Research Progress ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Early Hydration ◽  
Calcined Clay ◽  
Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

Effects of Various Amounts of Natural Pozzolans from Volcanic Scoria on Performance of Portland Cement Mortars

2017 ◽  
Vol 32 ◽  
pp. 36-52 ◽  
Author(s):  
Willy Hermann Juimo Tchamdjou ◽  
Sophie Grigoletto ◽  
Frédéric Michel ◽  
Luc Courard ◽  
Toufik Cherradi ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Portland Cement ◽  
Mechanical Strength ◽  
Calcium Hydroxide ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Natural Pozzolan ◽  
X Ray ◽  
Natural Pozzolans ◽  
Cement Mortars

The aim of this paper is to assess the possibility of using natural pozzolans (NPs) from Cameroonian volcanic scoria as supplementary cementitious materials (SCMs) in the production of Portland cement mortars. Four natural pozzolans (Black Natural Pozzolan: BNP, Dark-Red Natural Pozzolan: DRNP, Red Natural Pozzolan: RNP and Yellow Natural Pozzolan: YNP) with 3600, 4500, 4700 and 5200 cm2/g Blaine fineness respectively were produced from different colors (Black, Dark red, Red and Yellow) volcanic scoria in a laboratory mill. Natural pozzolans were characterized with regard to particle size distribution, particle shape, electrical conductivity, X-ray fluorescence (XRF) and X-ray diffraction (XRD). The calcium hydroxide consumption by NPs was assessed firstly by electrical conductivity measurements of calcium hydroxide/NPs suspensions with calcium hydroxide excess. Evidence of pozzolanic reactivity of NPs is revealed in hydrated lime pastes, and low reactivity was observed in aqueous suspensions. The effects of 15, 25, and 35 wt.% of NPs as cement substitution on the properties of Portland cement mortars were investigated. Different properties were studied such as setting time, consistency, mechanical strength, pozzolanic activity, absorption by capillarity and resistance to carbonation. The reactivity of NPs was also assessed by means of the mechanical strength development of mortars. The results obtained show that pozzolanic and hydraulic reactions take place in OPC systems. The correlation between mechanical strengths and physical properties of NPs has been established. The study concludes that using DRNP and RNP at 15 wt. % cement replacement can ameliorate globally the performance of mortar. Using all NPs at 35 wt. % has negative effect on the fundamental properties of cementitious mortars.

scholarly journals Exploring Structural Evolution of Portland Cement Blended with Supplementary Cementitious Materials in Seawater

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1210
Author(s):  
Solmoi Park ◽  
Jun Kil Park ◽  
Namkon Lee ◽  
Min Ook Kim
Keyword(s):  
Portland Cement ◽  
Tap Water ◽  
Structural Evolution ◽  
Extended Period ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Main Reaction ◽  
Strength Development ◽  
Main Reaction Product ◽  
Reaction Degree

The present study investigated the structural evolution of Portland cement (PC) incorporating supplementary cementitious materials (SCMs) exposed to seawater. The samples were made with replacing Portland cement with 10 mass-% silica fume, metakaolin or glass powder. The reaction degree of SCMs estimated by the portlandite consumption shows that metakaolin has the highest reaction degree, thus metakaolin-blended PC exhibits the highest strength. The control exposed to seawater exhibited 14.82% and 12.14% higher compressive strengths compared to those cured in tap water at 7 and 28 days. The samples incorporating metakaolin showed the highest compressive strength of 76.60 MPa at 90 days tap water curing and this was 17% higher than that of the control. Exposure to seawater is found to retard the rate of hydration in all SCM-incorporating systems, while the strength development of the neat PC system is enhanced. The main reaction product that forms during exposure to seawater is Cl-AFm and brucite, while it is predicted by the thermodynamic modelling that a significant amount of M-S-H, calcite and hydrotalcite is to form at an extended period of exposure time.

scholarly journals The properties of slag-silica fume ternary blended mortar with quarry dust

2020 ◽  
Vol 14 (1) ◽  
pp. 6443-6451 ◽  
Author(s):  
Chow Wee Kang ◽  
Cheah Chee Ban ◽  
Oo Chuan Wei ◽  
Part Wei Ken ◽  
Leow Khang Heng
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Drying Shrinkage ◽  
High Strength ◽  
Total Porosity ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Fine Aggregate ◽  
Granulated Blast Furnace Slag ◽  
Quarry Dust

High carbon emissions of manufactured Portland cement in the concrete industry have incurred several interests in reducing the use of Portland cement by partially replacing it with supplementary cementitious materials. Most of which, are by-products from other manufacturing industries. Hence, the main purpose of this study is to investigate the effects of different combinations of ternary blended mortars incorporating supplementary cementitious materials such as Ground Granulated Blast Furnace Slag (GGBS) and Densified Silica Fume (DSF). In this study, mortars were prepared with 100% quarry dust and GGBS was replaced with DSF at 2% step increments up to 16% at a w/b ratio of 0.24. At the same time OPC content was fixed at 50%. The compressive and flexural strength, drying shrinkage, and porosity of mortars were all tested. The results indicated that the increasing DSF content increases; GGBS reduces the superplasticizer dosage for the desired workability of the mortar. The utilization GGBS and DSF has improved the performances ternary blended mortar incorporating quarry dust as a fine aggregate in terms of mechanical strength, drying shrinkage and total porosity tested. The high strength ternary blended mortar incorporating GGBS and DSF exhibited optimum mechanical and durability performance at the OPC:GGBS:DSF ratio of 50:38:12.

Properties of Mortar Incorporating Ground Dune Sand as Cement Replacement Material

2014 ◽  
Vol 925 ◽  
pp. 334-338
Author(s):  
Omer Abdalla Alawad ◽  
Abdulrahman Alhoziamy ◽  
Mohd Saleh Jaafar ◽  
Abdulaziz Al-Negheimish ◽  
Farah Noor Abdul Aziz
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Sulfate Attack ◽  
Supplementary Cementitious Materials ◽  
Replacement Level ◽  
Dune Sand ◽  
Cement Replacement ◽  
Autoclave Curing

Supplementary cementitious materials provide economic and environmental advantages in concrete industry. In this study, natural ground dune sand (GDS) was used as cement replacement material to fabricate mortar specimens. Ordinary Portland cement was replaced by GDS at five levels of replacement (0, 10, 20, 30, and 40 %) by weight. The cast mortar specimens were cured under normal and autoclave curing conditions. Compressive strength, drying shrinkage and resistance to sulfate attack were investigated. Results showed that the compressive strength under normal curing decreased as the level of replacement increased. However, under autoclave curing compressive strength increased as the content of GDS increased with 30% being the optimum replacement level. Autoclave curing decreased the drying shrinkage of plain and GDS blended mixtures by about 70% compared to control mixture cured under normal curing. Up to 270 days, no sulfate attack was observed on the GDS blended mixtures regardless of the replacement level. The use of GDS to reduce the Portland cement consumption can have a significant impact on the sustainability and economy of concrete construction.

Evaluation of strength of concrete on different initial exposure condition

2020 ◽  
Vol 13 ◽  
Author(s):  
Sri Ram Krishna Mishra ◽  
Pradeep Kumar Ghosh ◽  
Manoj Kulshreshtha
Keyword(s):  
Portland Cement ◽  
High Strength ◽  
Cementitious Materials ◽  
General Purpose ◽  
Supplementary Cementitious Materials ◽  
Exposure Condition ◽  
Portland Cement Concrete ◽  
Initial Exposure ◽  
Skilled Manpower ◽  
Standard Practices

Background: The previous studies have focused curing effect of mainly on high strength concrete, where strict supervision is maintained. This study is based upon general purpose concreting work for commercial and residential construction in absence of skilled manpower and supervision. Objective: The objective of this study is to establish a thumb rule to provide 7 days initial curing for maintaining quality for unsupervised concreting irrelevant to type of cement and grading. Methods: In this study concrete samples made with locally available commercial cements were cured for various initial exposure. Results: The results shows that concrete cured after a gap of 4 days from the time of de-moulding have given lowest strength as compared to concrete cured in standard practices i.e. where proper curing protocol had been followed. Conclusion: Initial curing is most important aspect of gaining desired strength. The findings after this study shows that curing affects the strength of concrete in variable grading. Initial curing has great importance for concrete with all types of Portland cement. Concrete with supplementary cementitious materials gives lowest strength initially but results higher strength after 28 days as compared to Portland cement.

scholarly journals Special Issue: Supplementary Cementitious Materials in Concrete, Part I

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2291
Author(s):  
Alessandro P. Fantilli ◽  
Daria Jóźwiak-Niedźwiedzka
Keyword(s):  
Environmental Impact ◽  
Portland Cement ◽  
Building Materials ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Special Issue ◽  
Cement Production ◽  
Concrete Part

The environmental impact of the Portland cement production and the large use of cement-based building materials is a growing problem [...]

scholarly journals Use of Treated Non-Ferrous Metallurgical Slags as Supplementary Cementitious Materials in Cementitious Mixtures

2021 ◽  
Vol 11 (9) ◽  
pp. 4028
Author(s):  
Asghar Gholizadeh Vayghan ◽  
Liesbeth Horckmans ◽  
Ruben Snellings ◽  
Arne Peys ◽  
Priscilla Teck ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Strength Development ◽  
Supplementary Cementitious Material ◽  
Performance Requirements ◽  
Metallurgical Slags ◽  
Leaching Behaviour ◽  
Kinetics Of

This research investigated the possibility of using metallurgical slags from the copper and lead industries as partial replacement for cement. The studied slags were fayalitic, having a mainly ferro-silicate composition with minor contents of Al2O3 and CaO. The slags were treated at 1200–1300 °C (to reduce the heavy metal content) and then granulated in water to promote the formation of reactive phases. A full hydration study was carried out to assess the kinetics of reactions, the phases formed during hydration, the reactivity of the slags and their strength activity as supplementary cementitious material (SCM). The batch-leaching behaviour of cementitious mixtures incorporating treated slags was also investigated. The results showed that all three slags have satisfactory leaching behaviour and similar performance in terms of reactivity and contribution to the strength development. All slags were found to have mediocre reactivity and contribution to strength, especially at early ages. Nonetheless, they passed the minimum mechanical performance requirements and were found to qualify for use in cement.

scholarly journals A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3467
Author(s):  
Ankit Kothari ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Carbon Dioxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cold Climate ◽  
Supplementary Cementitious Materials ◽  
Short Exposure ◽  
Chemical Admixtures ◽  
Composite Cements ◽  
Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

scholarly journals The potential use of pumice in mine backfill

2020 ◽  
Vol 1 ◽  
Author(s):  
Mohammed A. Hefni
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Mining Industry ◽  
Strength Development ◽  
Natural Pozzolan ◽  
Mine Backfill ◽  
Natural Pozzolans ◽  
Cemented Backfill ◽  
Compressive Strength Development ◽  
Potential Use

Abstract The use of natural pozzolans in concrete applications is gaining more attention because of the associated environmental, economic, and technical benefits. In this study, reference cemented mine backfill samples were prepared using Portland cement, and experimental samples were prepared by partially replacing Portland cement with 10 or 20 wt.% fly ash as a byproduct (artificial) pozzolan or pumice as a natural pozzolan. Samples were cured for 7, 14, and 28 days to investigate uniaxial compressive strength development. Backfill samples containing 10 wt.% pumice had almost a similar compressive strength as reference samples. There is strong potential for pumice to be used in cemented backfill to minimize costs, improve backfill properties, and promote the sustainability of the mining industry.

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