The need for reducing the carbon footprint and effect of hazardous gases, etc., released from the construction sectors and other product manufacturing industries on the environment is the need of the hour. In this regard, the construction sector has been utilizing some of the wastes generated from various sources in making concrete. Notable among them is the Ground granulated blast furnace slag (i.e. GGBS) as a partial substitution of cement. Further, waste foundry sand, a by-product of the foundry industry is observed to be an appropriate alternative to partial replacement of fine aggregate and demolition waste as a partial replacement of coarse aggregate. These waste utilizations have addressed some of the global environmental concerns like solid waste management, scarcity of landfilling, sustainability etc. but there is still is inefficient, given the rate at which we are producing waste. This paper presents an overview of some of the recent research published on the utilization of wastes in the production of sustainable RMC/SMC. It also presents the effect of waste utilization in concrete on mechanical, microstructural and durability factors.

This study aimed to determine the strength and chloride content of marine concrete if fly ash and silica fume were used to replace a portion of the conventional Portland cement (OPC). The study was done so that these goals could be reached. W/C of 0.42 to make M30 grade concrete. Even though the number of parts that go into making OPC concrete is the same, using SP cuts the amount of water needed to make mixed concrete by 20%. Several different experiments that were done with different mixtures back up this conclusion. Compressive strength, flexural strength, and split tensile strength are the three types of strength that have been looked at. For the durability test, water-soluble chloride (WSC) will be used. SEM, which stands for scanning electron microscopy, will be used for the microstructural analysis. According to the test results, the compressive strength of concrete that had been treated with dosages of SP and had 10% fly ash showed a degradation factor (DF) of less than 5% after being exposed to the elements for a year. Even though the concrete had been out in the weather, this was still the case. After 90 days, both the split tensile strength and the flexural strength have a DF of 0.95 percent, but the flexural strength only has a DF of 0.5 percent.

Crack width evaluation of flexural RC member is evaluated analytically by two significant formulas given by researchers and four standard code i.e. IS 456-2000, BSEN 1992-1-1-2004, ECP 203-2007, ACI 318-95 and compared. Parameters such as clear cover, the effect of diameter, variation of depth, number of bars with the same cross-section and increasing external moment are considered for computing the crack width. From the study of results of this study, it can be concluded that clear covers estimated based on IS 456 2000 are highest and those estimated based on EGYPTIAN CODE; 203-2007 are lowest as compared to other codes and mathematical models considered in this study. It can also be concluded that crack width increases with increase in clear cover or external moment while it decreases with increase in reinforcement diameter, depth of the beam or number of bars.

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