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This chapter builds monthly time-series of Divisia monetary aggregates for the Gulf area for the period of June 2004 to December 2011, using area-wide data. We also offer an “economic stability” indicator for the Gulf Cooperation Council (GCC) area by analyzing the dynamics pertaining to certain variables such as the dual price aggregates, aggregate interest rates, and the Divisia aggregate user-cost growth rates. Our findings unfold the superiority of the Divisia indexes over the officially published simple-sum monetary aggregates in monitoring the business cycles. There is also direct evidence on higher economic harmonization between GCC countries – especially in terms of their financial markets and the monetary policy. Monetary policy often uses interest rate rules, when the economy is subject only to technology shocks. In that case, money is nevertheless relevant as an endogenous indicator (Woodford, M. (2003). Interest and prices: Foundations of a theory of monetary policy. Princeton, NJ: Princeton University Press.). Properly weighted monetary aggregates provide critical information to policy-makers regarding inside liquidity created by financial intermediaries. In addition, policy rules should include money as well as interest rates, when the economy is subject to monetary shocks as well as technology shocks. The data show narrow aggregates growing while broad aggregates collapsed following the financial crises. This information clearly signals problems with the financial system's ability to create liquidity during the crises.

In this chapter, using a combination of long-run and sign restrictions to identify aggregate monetary and productivity factors, I find that the monetary factor is responsible for long swings in nominal variables but has little effect on fluctuations in output, real wage, or labor input growth. The productivity factor in addition to increasing output growth and real wage growth in the short and long run, also results in increases in labor input and decreases in prices, but the quantitative effect of the productivity factor on labor input is relatively small. These results are robust to the number of factors included in the model and to alternative priors about the short-run effects of the monetary factor, and to the inclusion of oil prices. Oil prices, in fact, appear to be largely driven by the other aggregate factors.

This study aims to practically determine the optimum proportion of aggregates to attain the desired strength of geopolymer concrete (GPC) and then compare the results using established analytical particle packing methods. The investigation further aims to assess the influence of various amounts of recycled aggregate (RA) on properties of low-calcium fly ash-based GPC of grade M25.

Fine and coarse aggregates were blended in various proportions and the proportion yielding maximum packing density was selected as the optimum proportion and they were compared with analytical models, such as Modified Toufar Model (MTM) and J. D. Dewar Model. RAs for this study were produced in laboratory and they were used in various amounts, namely, 0%, 50% and 100%. 12M NaOH solution was mixed with Na₂SiO₃ in the ratio of 1:2. The curing of concrete was done at the temperatures of 60° and 90 °C for 24, 48 and 72h.

The experimentally obtained optimum proportion of coarse to fine aggregate was 60:40 for all amounts of RA. Meanwhile, MTM and Dewar Model resulted in coarse aggregate to fine aggregates as 40:60, 45:55, 55:45 and 55:45, 35:65, 60:40, respectively, for 0% 100% and 50% RAs. The compressive strength of GPC elevated with the increase in curing regime. In addition, the ultrasonic pulse velocity also displayed a similar trend as that of strength.

The GPC with 50% RAs may be considered for use, as it exhibited superior properties compared to GPC with 100% RAs and was comparable to GPC with natural aggregates. Furthermore, compressive strength is correlated with split tensile strength and ultrasonic pulse velocity.

One of the most contested and anticipated research issues is the acceptability of using recycled aggregates instead of fresh aggregates. This study aims to look at the possibility of replacing fresh aggregates with 15%, 30%, 60% and 100% recycled aggregates.

The research is divided into two stages. The compressive, split tensile, flexural and bond strength of the various mixes were examined in the first phase using untreated recycled concrete aggregates (RCA). The second phase entails chemically treating RCA with a 10% 0.1 M sodium metasilicate solution to evaluate differences in strength, indicating the success of the treatment performed. Microstructural experiments such as scanning electron microscopy and X-ray diffraction were also conducted to evaluate the formation of interfacial transition zone (ITZ) in treated and untreated RCA specimens.

The observed findings reveal a decrease in concrete strength with increasing RCA concentration; however, when treated RCA was used, the strengths increased significantly when compared to untreated samples. The findings also include curves indicating the correlation between compressive strength and other mechanical strength parameters for an optimum mix of concrete prepared with 30% RCA replacement.

The study through its novel approach, demonstrates the effect of pretreatment of RCA in the absence of any standardized chemical treatment methodology and presents significant potential in minimizing reliance on fresh aggregates used in concrete, lowering building costs and promoting the use of waste materials in construction.

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.