RESEARCH PAPER Application of Talc as an Eco-Friendly Additive to Improve the Structural Behavior of Porous Concrete Armin Azad 1 • Sayed-Farhad Mousavi 1 • Hojat Karami 1 • Saeed Farzin 1 Received: 24 June 2017 / Accepted: 24 September 2018 Ó Shiraz University 2018 Abstract Talc is an eco-friendly material used in various domains. In this study, talc, quartz and lime sand were added for improving the performance of porous concrete. For this, talc/quartz and lime sand were used as substitute with 5–30% and 5–15% of aggregates, respectively. Compressive strength, porosity and permeability of the porous concrete blocks and their draining capacity were the tested characteristics. Results showed that although by increasing the amount of talc, quartz and lime sand, compressive strength was improved, permeability and porosity were reduced. However, despite the significant difference in hardness of talc and quartz, mixtures containing talc had acceptable performance and were close to quartz so that the average compressive strength of talc samples was only 0.4 MPa less than the quartz ones. It was also found that threshold value for the addition of talc to increase the strength of porous concrete was 25% and over this rate makes no difference in resistance and even reduces it. Results also revealed that all mixtures had good performance in drainage of synthetic urban runoff—the least-permeable talc sample drained 40-mm runoff in 69 s. Also, the most impermeable quartz specimen drained the 40-mm runoff in 44 s. Generally, the mentioned results indicated that talc, as an eco-friendly additive, had acceptable performance in improving the properties of porous concrete. Keywords Porous concrete Á Talc Á Quartz Á Urban runoff Á Flood management 1 Introduction Porous concrete is a special type of concrete with lots of interconnected pores (ACI 522R 2006). To obtain high porosity and continuous pores, the structure of such con- crete should be different from its normal type. In porous concrete, variation of aggregation range is low and gra- dation has no fine grains, or has a small amount of it. On the other hand, the amount of cement used in this type of concrete is lower than normal, and its slump is zero (Ghafoori and Dutta 1995). The use of porous concrete due to its compatibility with the environment has experienced significant growth since 1980s in many countries, espe- cially America and Japan (Bhutta et al. 2012). Water passes the porous concrete easily. That is why, one can use it as an alternative to road pavement and sidewalk. Moreover, it can be used for recharging groundwater, a medium for patios and greenhouses, reducing flooding and downstream erosion, reducing flood-water velocity, management of urban runoffs, and as drainage system in infrastructure of roads and hydraulic structures. This type of concrete is a good insulation for temperature and has good resistance against cold and frost (Agar-Ozbek et al. 2013). Technology of porous concrete pavement increases the efficient use of land because it decreases the need for recycling ponds, wetlands and flood management. For this reason, porous concrete can be effective in reducing the overall cost of the project (Tennis et al. 2004). However, one of the problems of this type of concrete is its low compressive strength. Therefore, porous concrete can be used in areas with medium and light traffic and even & Armin Azad A.Azad@semnan.ac.ir Sayed-Farhad Mousavi fmousavi@semnan.ac.ir Hojat Karami hkarami@semnan.ac.ir Saeed Farzin Saeed.farzin@semnan.ac.ir 1 Faculty of Civil Engineering, Semnan University, Semnan, Iran 123 Iran J Sci Technol Trans Civ Eng https://doi.org/10.1007/s40996-018-0177-1