Testing of Composite Mortars Based on Supplementary Cementitious Materials: Estimating Durability and Thermal Properties

Author(s):  
N. Latroch ◽  
A.S. Benosman ◽  
N. Bouhamou ◽  
B. Belbachir ◽  
Y. Senhadji ◽  
...  

The growing need for building material resources, and the requirements to preserve the environment, in a vision of sustainable development, has become necessary to study reinforcement techniques, using composite materials. Using local organic or inorganic materials in construction fields and public works is particularly important. Polymer mortar composites (PMC) are usually employed in the building industry as finishing materials, tile adhesive (mortar-adhesive) or façade coating. In repair applications, the addition of soluble polymer (latex) allows improving the adhesion properties of the materials used as coating. The use of mineral additives as partial substitutes for cement, in construction sites as well as in ready-to-use mortars, is an unknown practice in our country. For this reason, we thought it is crucial to study and assess the influence of these additions on the properties of cured composite. Supplementary cementitious materials (SCM) used in this study are silica fume and natural pozzolan, which necessarily need to be valorized.The present research work aims to use a specific experimental methodology that is able to identify the relationship between the degree of substitution by the mineral additives, the polymer and the modifications to the properties of fresh and hardened cement mixtures. Therefore, five PMC combinations were formulated from different percentages of additions, i.e. natural pozzolan (NP: 25%w), silica fume (Sf: 5%w) and polymer latex (P: 0, 5, 7.5, 10, 12.5 and 15%w). Their durability factors, such as the porosity accessible to water and capillary absorption rate (sorptivity), were characterized, at different maturities. An attempt was also made to determine the thermal coefficients. The results obtained were compared with those of the reference mortars, made with Portland cement (CEMI). They showed that the decrease in porosity, sorptivity and thermal conductivity depends on the pair “SCMs/polymer”. But overall, the addition of polymer latex and pozzolanic additions have a beneficial effect on the durability and thermal properties of the composite materials.

2016 ◽  
Vol 678 ◽  
pp. 123-134 ◽  
Author(s):  
B. Belbachir ◽  
A.S. Benosman ◽  
H. Taïbi

Degradation of building materials is an important phenomenon influencing their design and utilization. Mineral-based polymer-mortar composites (PMC) are often used as inexpensive promising materials to prevent the deterioration of constructions or remedy various reinforced concrete structures and they are used as materials for energy efficiency in buildings. In repair applications, polymer addition allows improving the adhesion properties of materials used in coating. With the intention of improving the sustainability of these composites, the influence of latex polymer and supplementary cementitious materials (natural pozzolan and silica fume) additions on the characteristics of these composites was investigated in aggressive media, such as acids. Mortars made with local pozzolanic mineral admixtures, obtained by substituting cement by different proportions of polymer (0, 5, 7.5, 10, 12.5 and 15%) were conserved in acidic solutions for 56 days. The microstructural analysis of these mortars was performed, using the X-ray diffraction technique, after 56 days of exposure to acid attack. The obtained results enable to bring out the beneficial effect of adding a latex polymer and other pozzolanic additives into modified materials on resistance to acid attacks. So, these composite materials can be recommended as materials for energy efficiency in buildings.


Author(s):  
Khashayar Jafari ◽  
Farshad Rajabipour

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.


Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4248
Author(s):  
Xingxing Li ◽  
Ying Ma ◽  
Xiaodong Shen ◽  
Ya Zhong ◽  
Yuwei Li

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.


2020 ◽  
Vol 853 ◽  
pp. 142-149
Author(s):  
Ahmad Khartabil ◽  
Samer Al Martini

Understanding the thermal properties of a construction material is necessarily to evaluate its heat transfer resistance that has a major contribution to the energy-efficiency required to achieve sustainable structure. Thermal properties are evaluated through three main parameters namely: thermal conductivity, thermal resistivity and thermal transmittance. The aforementioned parameters are commonly referred as K-value, R-value, and U-value respectively. Recent regulations by Dubai municipality enforced to use sustainable concrete in construction. This is by replacing cement with supplementary cementitious materials (SCMs), such as grand granulated blast furnace slag (GGBS) and fly ash. The use of grand granulated blast furnace slag (GGBS) at relatively high percentage replacement became a typical practice in ready-mixed concrete industry in Dubai. As such, it is essential to characterize the thermal properties of this sustainable concrete. The current paper investigates the thermal properties of sustainable concrete mixtures incorporating supplementary cementitious materials, air entrainment additives, polypropylene and hybrid synthetic fiber. K-value, R-value and U-value are evaluated in accordance with ASTM C518. Additionally, hardened density of all investigated mixtures are measured. The results show that the foamed concrete has better heat transfer resistance than that for the non-air entrained mixture.


2014 ◽  
Vol 660 ◽  
pp. 162-167
Author(s):  
Elbachir Elbahi ◽  
Sidi Mohammed El Amine Boukli Hacene

The resonance frequency method is one of many non-destructive tests which allow us to evaluate construction materials. It was used to determine the dynamic properties of concrete, required in structures design and control, also considered as the key elements for materials dynamic. In this study, we chose a non-destructive approach to quantify-in laboratory-, the influence of adding “crushed limestone” and “natural pozzolan” on local concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental used plan, allowed us to determine the dynamic modulus of elasticity, the dynamic modulus of rigidity of different formulated concretes.


2005 ◽  
Vol 32 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Nabil Bouzoubaâ ◽  
Benoît Fournier

The data gathered on the current situation of supplementary cementing materials (SCMs) in Canada have shown that around 524 000, 347 000, and 37 000 t of fly ash, ground granulated blast furnace slag (GGBFS), and silica fume were used in cement and concrete applications in 2001, respectively, which represents 11%, 90%, and 185% of the quantity produced. The remaining 10% of GGBFS produced was used in the US, and 17 000 t of silica fume were imported from the US and Norway to meet market demand. Fly ash appears to be the only material that is underused and that represents a potential for increased use of SCMs in Canada. For the GGBFS, the quantity produced can be increased if the demand increases. This investigation has shown, however, that there are policy, technical, and economic barriers to the increased use of SCMs in Canada. Some solutions were proposed to overcome these barriers and are summarized in the conclusions of the paper.Key words: fly ash, slag, silica fume, concrete, blended cement.


Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8291
Author(s):  
Mays A. Hamad ◽  
Mohammed Nasr ◽  
Ali Shubbar ◽  
Zainab Al-Khafaji ◽  
Zainab Al Masoodi ◽  
...  

The increase in cement production as a result of growing demand in the construction sector means an increase in energy consumption and CO2 emissions. These emissions are estimated at 7% of the global production of CO2. Ultra-high-performance concrete (UHPC) has excellent mechanical and durability characteristics. Nevertheless, it is costly and affects the environment due to its high amount of cement, which may reach 800–1000 kg/m3. In order to reduce the cement content, silica fume (SF) was utilized as a partial alternative to cement in the production of UHPC. Nevertheless, SF is very expensive. Therefore, the researchers investigated the use of supplementary cementitious materials cheaper than SF. Very limited review investigates addressed the impact of such materials on different properties of UHPC in comparison to that of SF. Thus, this study aims to summarize the effectiveness of using some common supplementary cementitious materials, including fly ashes (FA), ground granulated blast furnace slag (GGBS), metakaolin (MK) and rice husk ashes (RHA) in the manufacturing of UHPC, and comparing the performance of each material with that of SF. The comparison among these substances was also discussed. It has been found that RHA is considered a successful alternative to SF to produce UHPC with similar or even higher properties than SF. Moreover, FA, GGBS and MK can be utilized in combination with SF (as a partial substitute of SF) as a result of having less pozzolanic activity than SF.


2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Dehui Wang ◽  
Zhiwen Zhang

It is well known that supplementary cementitious materials (SCMs) have obvious effects on the properties of concrete. In order to understand the relationship between cementitious materials and properties of ultrahigh strength concrete (UHSC), the cementitious compositions of UHSC were designed by the simple-centroid design method. The effects of cementitious compositions on the properties of UHSC were investigated. It was found that the incorporation of silica fume (SF) improved the flowability and strength of UHSC, but it decreased the time of acceleration period, calcium hydroxide (CH) content, and porosity of UHSC at a certain content. The incorporation of fly ash (FA) increased the flowability, time of acceleration period, and porosity of UHSC, but it decreased the strength and CH content of UHSC. The relationships between cement, silica fume, and fly ash and the properties of UHSC were calculated based on the simple-centroid design method.


2021 ◽  
Vol 72 (1) ◽  
pp. 76-83
Author(s):  
Lam Le Hong ◽  
Lam Dao Duy ◽  
Huu Pham Duy

The demand for High Performance Concrete (HPC) is steadily increasing with massive developments. Conventionally, it is possible to use industrial products such as silica fume (SF), fly ash, as supplementary cementitious materials (SCM), to enhance the attributes of HPC. In recent years, nano-silica (NS) is used as an additive in added mainly to fill up the deviation arises with the addition of SF for HPC. This study aims to optimize the proportion of NS (produced in Vietnam) in the mixture used for fabricating 70 MPa high-performance concrete. SiO2 powder with particle size from 10 to 15 nm were used for mixing. A series of compressive strength test of HPC with nano-SiO2 varied from 0 to 2.8 percent of total of all binders (0%, 1.2%, 2%, 2.8%), and the fixed percentage of silica fume at 8% were proposed. Results show compressive strength increases with the increase of nano-SiO2, but this increase stops after reaching 2%. And at day 28 of the curing period, only concrete mixture containing of 8% silica fume and 2% nano-SiO2, had the highest compressive strength.


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