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A current trend is to use waste and by‐products in concrete to replace binders and aggregates. This trend reduces the impact on the environment and the use of finite natural resources. This paper aims to investigate whether concrete which includes crushed, graded and washed recycled construction demolition waste, used as a coarse aggregate, can be manufactured to a comparable strength as concrete manufactured from virgin aggregates.

Laboratory testing investigated the strength development of concrete manufactured with varying degrees of coarse aggregate replacement. All of the concrete samples were tested at five, seven, 14 and 21 days and the concrete with the recycled aggregate was compared to a plain control sample manufactured with virgin aggregates. The mixes tested against the control sample were: 100 per cent gravel replacement with recycled aggregate, and the same mix with a viscosity modifying agent. A 50 per cent partial coarse aggregate replacement was used in one batch to compare against the control and the 100 per cent recycled aggregate concrete. Compressive strength was used to compare the different concrete batch performance. Density was used to indicate the degree of particle packing and void content which was measured across the range of samples to evaluate the relationship between the different concrete mixes.

The optimum concrete mix design using recycled construction waste was obtained by using a 50‐50 per cent mix of virgin gravel and recycled aggregates. Using recycled construction waste as a 100 per cent coarse aggregate replacement produces concrete with a lower compressive strength when compared to concrete made with virgin aggregates.

The paper investigates ways of incorporating construction demolition waste as recycled aggregate to reduce the environmental impact of the production of concrete.

The purpose of this paper is to conduct a laboratory investigation on measuring the tensile strength of recycled concrete using a double punch test. Furthermore, one of the main goals of this study is to compare the tensile and compressive strengths of recycled concrete samples.

Recycled concrete samples were made with variables such as aggregate type (natural stone and aggregate recycled concrete), different water-to-cement ratios and different treatment conditions in the first stage. In the next stage, the double punch test was performed on them, and finally the results obtained from experiments were analyzed and investigated.

According to the above tests, it was concluded that: first, according to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Second, upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. Third, upon investigating the results of tensile strength, it can be said that the Barcelona test results were closer to the direct tensile test results compared to the Brazilian test results. This indicates the higher viability of Barcelona’s test results. Fourth, the results obtained from the Barcelona tensile test for recycled concrete were closer to the results of the direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. Fifth, the effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. Sixth, the relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregates compared to recycled concrete. Seventh, the dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregates, but lesser of this dispersion was observed in the compressive strength.

According to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. On the basis on the results of the tensile strength, it can be said that the Barcelona test results were closer to the results of the direct tensile test compared to those of the Brazilian test. This indicates the higher viability of Barcelona’s test results. The results obtained from the Barcelona tensile test for recycled concrete were closer to the results of direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. The effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. The relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregate compared to recycled concrete. The dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregate, but lesser of this dispersion was observed in the compressive strength.

The purpose of this paper is to investigate whether concrete that includes un‐graded recycled aggregates can be manufactured to a comparable strength to concrete manufactured from virgin aggregates.

A paired comparison test was used to evaluate the difference between concrete made with virgin aggregates (plain control) and concrete including recycled waste. Un‐graded construction demolition waste and un‐graded ground glass were used as aggregate replacements. With regard to concrete, compressive strength is widely used as a measure of suitability as being fit for purpose. Therefore compressive strength was mainly used to compare the different concrete batches; however density was measured across the range of samples.

The findings show that a lower average compressive strength is achieved when compared to the plain control sample manufactured with virgin aggregates. Correct particle packing may not be achieved and grading of aggregates is essential prior to mix design. The recycled aggregate was highly variable in terms of the fine particle content, which affected the water demand of the concrete.

This manufacturing practice is considered necessary because of the current trend in using waste products in concrete to replace binders and aggregates; thus reducing the impact on the environment and use of finite natural resources. The research shows the risk of mixing concrete using a simple aggregate replacement without careful aggregate grading and adjustments to the mix design.

The paper examines 100 per cent ungraded aggregate replacement with glass and demolition waste.

In recent years, fire accidents in engineering structures have often been reported worldwide, leading to a severe risk to life and property safety. The present study is carried out to evaluate the performance of Ground Granulated Blast Furnace Slag (GGBS) and fly ash–blended laterized mortars at elevated temperatures.

This test program includes the replacement of natural river sand with lateritic fine aggregates (lateritic FA) in terms of 0, 50 and 100%. Also, the ordinary Portland cement (OPC) was replaced with fly ash and GGBS in terms of 10, 20, 30% and 20, 40 and 60%, respectively, for producing blended mortars.

This paper presents results related to the determination of residual compressive strengths of lateritic fine aggregates-based cement mortars with part replacement of cement by fly ash and GGBS exposed to elevated temperatures. The effect of elevated temperatures on the physical and mechanical properties was evaluated with the help of microstructure studies and the quantification of hydration products.

A sustainable cement mortar was produced by replacing natural river sand with lateritic fine aggregates. The thermal strength deterioration features were assessed by exposing the control specimens and lateritic fine aggregates-based cement mortars to elevated temperatures. Changes in the mechanical properties were evaluated through a quantitative microstructure study using scanning electron microscopy (SEM) images. The phase change of hydration products after exposure to elevated temperatures was qualitatively analyzed by greyscale thresholding of SEM images using Image J software.

This study aims to investigate the compressive strength of concretes incorporating Linz-Donawitz slag (LD slag) as partial replacement for natural fine and coarse aggregates and compare them with traditional concrete.

The natural fine and coarse aggregates were replaced by weight simultaneously up to 100% with LD slag aggregates at an incremental increase of 20%. Concrete of grades M20, M25, M30, M35 and M40 were cast, cured and tested with standard cube specimens to study the density and compressive strength of reference and LD slag aggregate concretes (LDSACs). The concrete specimens were exposed to elevated temperatures, i.e. 100 to 900 °C at an equal interval of 100 °C and tested to study the variation in density and residual compressive strength.

The results from the experiments reveal that the LDSAC yields a higher density than that of the reference concrete and also undergo less density variation when exposed to elevated temperatures. In addition, the residual compressive strength of LDSAC specimens was significantly higher than that of the reference concrete.

LD slag is believed to be stronger and more durable than locally available limestone aggregates or blast furnace slag. Moreover, it is necessary to study its strength and other properties to determine whether it can be successfully used as an aggregate in concrete universally.

Use of LD slag as aggregates in concrete will convert LD slag into a value added product and as an alternative to the existing natural aggregates which will help in maintaining ecological balance and save valuable lands.

The economically weaker section of the society may now use LDSAC as waste utilization will bring down the overall cost and hence it will benefit people on large scale.

Use of LD slag as aggregate in concrete can help find an alternative to the existing natural aggregates which will save the ecosystem and at the same time help in reducing the industrial waste on a large scale.

The purpose of this research is to evaluate construction and industrial waste materials in concrete using different additives.

The experimental study investigated the effect of waste foundry sand (WFS), waste glass (GW) as partial substituent to natural sand and addition of waste glass fibers (GFs) and silica fume (SF) in natural/construction waste aggregate concrete on mechanical properties, durability and microstructure using.

The results reveal significant strength enhancement on using two admixtures, the maximum increase in compressive strength was obtained on using 20% WFS and 0.75% GF for both natural (75% increment) and construction waste (72% increment) coarse aggregates. Using three admixtures simultaneously, the maximum enhancement in compressive strength was found for (WFS(20%) + GW(10%) + GF(0.75%)) for both natural aggregates (122% increment) and construction waste (114% increment) coarse aggregates as compared to control mix. The 28 days split tensile and flexural strength of natural/construction waste aggregate concrete improve with age appreciably for optimal contents of single, two or three admixtures and the maximum tensile and flexural strength increment was 135 and 97% for mix (WFS(20%) + GW(10%) + GF(0.75%)) with natural aggregates as compared to control mix. The microstructural analysis results indicate improved microstructure upon partial substitution of sand with WFS, GW and SF along with addition of waste GFs.

The use of construction and industrial waste as a substituent to natural aggregate/sand will provide far reaching benefits for the green construction and the environment at large.

The durability of concrete containing recycled aggregates, sourced from concrete specimens that have been tested in laboratory testing facilities, remains understudied. This paper aims to present the results of experiments investigating the effect of incorporating such type of concrete waste on the strength and durability-related properties of concrete.

A total of 77 concrete cylinders sized Ø100 × 200 mm with varying amount of recycled concrete aggregate (RCA) (0%–100% by volume, at 25% increments) and maximum aggregate size (12.5, 19.0 and 25.0 mm) were fabricated and tested for slump, compressive strength, sorptivity and electrical resistivity. Disk-shaped specimens, 50-mm thick, were cut from the original cylinders for sorptivity and resistivity tests. Analysis of variance and post hoc test were conducted to detect statistical variability among the data.

Compared to regular concrete, a reduction of slump (by 18.6%), strength (15.1%), secondary sorptivity (31.5%) and resistivity (17.0%) were observed from concrete containing 100% RCA. Statistical analyses indicate that these differences are significant. In general, an aggregate size of 19 mm was found to produce the optimum value of slump, compressive strength and sorptivity in regular and RCA-added concrete.

The results of this study suggest that comparable properties of normal concrete were still achieved by replacing 25% of coarse aggregate volume with 19-mm RCA, which was processed from laboratory-tested concrete samples. Therefore, such material can be considered as a potential and sustainable alternative to crushed gravel for use in light or nonstructural concrete construction.

The purpose of this paper is to make a contribution to understanding the influence of factors such as the water/cement (W/C) ratio and the granular class on the mechanical and physical properties of high-strength concretes (HSCs). In the formulations of HSC, aggregates by their high mass and volume proportion play an important role. When selecting aggregates, it is necessary to know their intrinsic properties. These properties influence the performance of concrete, in particular the quality of the granulate cimentary adhesion.

This experimental study focused on the effect of W/C ratio (0.25, 0.30, 0.35), the effect of replacing a part of cement by silica fume (SF) (8%), the effect of fraction of aggregate on properties of fresh and hardened concrete, the effect of different environment conversation like drinking water and sea water on compressive strength and the study of absorption of water and softening using the mix design method of the University of Sherbrooke combined with the Dreux-Gorisse method which gives good results.

At the end of our work, the examination of the results obtained made it possible to establish the correlations between the formulations studied and the physicomechanical characteristics of the concrete compositions (HSC25, HSC16, HSC8). The results of this study show that the use of three granular classifications (DMAX8, DMAX16 and DMAX25) and three report W/C (0.25, 0.30 and 0.35) in two different conservation environment (drinking water and sea water) give HSCs, HSC25 with an W/C = 0.25 ratio has reached the largest mechanical strength of 90 MPa for different environments of conservation. For selecting aggregates, it is necessary to know their intrinsic properties, these properties influence the strength of concrete. In general, there is a slight decrease in the compressive resistance of the specimens stored in seawater, it can be said that the conservation life has not had effect on the resistance (28 days). The effect of aggressive environment can appear in the long term.

Mixed design and concrete fabrication with a 28-day compressive strength of up to 68 MPa or more of 90 MPa can now be possible used in Jiel (Algeria), and it should no longer be considered to be used only in an experimental domain. Addition of SF in concrete showed good development of strength between 7 and 28 days, depending on the design of the mix.

Concrete containing 8% SF with W/B of 0.25 has higher compressive strength than the other concretes, and concretes with SF are more resistant than concretes without SF, so it is possible to have concrete with a compressive strength of 82 MPa for W/C 0.25 without SF. Like as a result, we can avoid the use of SF to affect the strength of concrete at compressive strength of 68 MPa, and a slump of 21 cm, because the SF is the most expensive ingredient used in the composition of concrete and is therefore very important economically. One of the main factors of production of HSC above 90 MPa is use of aggregate DMAX25, which is stronger with W/B of 0.25 and 0.30.

This mixtures leads to a very dense microstructure and low porosity and produces increased permeability of HSC and is able to resist the penetration of aggressive agents. This combination has a positive effect on the economy of concrete.

The combination of the Dreux-Gorisse method with the Sherbrook method is very beneficial for determining the percentage of aggregates used, and the use of coarse aggregates of Jijel to obtain HSC with 90 MPa and 16 cm of workability.

Most developing countries simply dump ferrochrome slag as waste which occupies huge areas of useful land. The purpose of this study is to underscore the significance of reusing ferrochrome slag as a sustainable and eco-friendly road aggregate material, with the added benefits of preventing possible environmental pollution and promoting sustainable mining of non-renewable construction materials.

Physical-mechanical characteristics were investigated using various South African National Standards test procedures. Chemical and mineralogical characteristics were evaluated using the X-ray fluorescence and the X-ray diffraction techniques, respectively. The toxicity characteristic leaching procedure test was used to evaluate the slag’s environmental suitability. Using two cement types, cement proportions of 1%, 2% and 3% of the slag aggregate weight mixed with optimum moisture content of the non-treated compacted slag were used to make lightly cemented ferrochrome slag aggregate (LCFSA) composites, subsequently tested for compressive strength.

Ferrochrome slag aggregates have excellent physical-mechanical characteristics that conform to international specifications for use in road base construction. The slag can be classified as non-hazardous solid waste. However, in acidic environments, some toxic elements may leach from the slag and pollute the environment. Optimum cement contents of 2.3% (CEM II) and 2.6% (CEM VB) can be mixed with the slag to produce LCFSA for road bases.

No research was found in literature on the use of LCFSA in road bases. This research, therefore, presents new data on mix design and strength properties of LCFSA as well as some physical-chemical characteristics of coarse ferrochrome slag aggregate.

This study explores the association between individual investor information demand and two measures of market uncertainty – aggregate market uncertainty and disaggregate industry-specific market uncertainty. It extends the literature by being the first to empirically examine investor information demand and disaggregate market uncertainty.

This paper constructs a measure of information search by using the Google Search Volume Index and computes measures of aggregate and disaggregate market uncertainty using institutional investors' trading data from Ancerno Ltd. The relation between market uncertainty, as measured by trading disagreements among institutional investors, and information search is analyzed using an OLS (Ordinary Least Squares) regression model.

This paper finds that individual investor information demand is significantly and positively correlated with aggregate market uncertainty but not associated with disaggregated industry uncertainty. The findings suggest that individual investors may not fully incorporate all relevant uncertainty information and that ambiguity-related market pricing anomalies may be more associated with disaggregate market uncertainty.

This study presents an examination of aggregate and disaggregate measures of market uncertainty and individual investor demand for information, shedding light on the efficiency of the market in incorporating information. A limitation of our study is that our data for market uncertainty is based on investor trading disagreement from Ancerno, Ltd. which is only available till 2011. However, we believe the implications are generalizable to the current time period.

This study provides the first concurrent empirical assessment of investor information search and aggregate and disaggregate market uncertainty. Prior research has separately examined information demand in these two types of market uncertainty. Thus, this study provides information to investors regarding the importance of assessing disaggregate component measures of the market.

This paper is the first to empirically examine investor information search and disaggregate market uncertainty. It also employs a unique data set and method to determine disaggregate, and aggregate, market uncertainty.