Partial or total replacement of Portland cement clinker by SCMs (Supplementary Cementitious Materials) is a priority for the cement industry in its pursuit of global sustainable development and eco-friendly binder manufacture. The most widely used SCMs include industrial by-products such as blast furnace slag, fly ash and red mud. Alkali-activated cements manufactured with SCMs may reduce the need for Portland clinker by up to 90 wt%–100 wt% with no significant decline in material strength. The trade-off, however, is the risk of higher than legally allowable levels of radioactivity and unbound heavy metals (Cd, Hg, Ni, Pb, Cr), which may leach into the soil with the concomitant adverse implications for human health and the environment.

This study assessed the mechanical strength, leachability and natural radioactivity of alkali-activated cement paste containing industrial waste-based SCMs (blast furnace slag, fly ash and red mud) and Pb and Ni compounds.

Strength was highest in alkali-activated slag and slag/fly ash pastes and lowest in the red mud-containing materials. The addition of Pb or Ni sulphates had no adverse effect on this parameter. Alkaline and OPC pastes showed a high level of immobilization of both lead and nickel ions.

According to the radiological findings, the Activity Concentration Index (I) was higher in red mud than in OPC, blast furnace slag or fly ash. With (I) values lower than 1, however, all the hydrated/activated materials studied would be EU directive-compliant. Nonetheless, the use of these new materials will depend not only on the activity concentration index, but also on their physical and chemical properties and the quality tests that must be passed to conform to legal requirements.

水泥行业在追求全球可持续发展和环保型粘合剂生产方面，优先考虑用SCM（补充胶凝材料）部分或全部替代波特兰水泥熟料。使用最广泛的SCM包括工业副产品，例如高炉矿渣，粉煤灰和赤泥。用SCM生产的碱活化水泥可以减少对波特兰熟料的需求，最多可减少90 wt％–100 wt％，而材料强度不会显着下降。但是，要权衡取舍的是，放射性和未结合的重金属（Cd，Hg，Ni，Pb，Cr）的含量可能超过法律允许的水平，这些污染物可能会渗入土壤，并对人类健康和健康造成不利影响。环境。

这项研究评估了含工业废渣SCM（高炉矿渣，粉煤灰和赤泥）以及Pb和Ni化合物的碱活化水泥浆的机械强度，浸出性和天然放射性。

强度在碱活化矿渣和矿渣/粉煤灰浆中最高，在含赤泥的材料中最低。硫酸铅或镍的添加对该参数没有不利影响。碱性和OPC糊剂显示出高水平的铅和镍离子固定化。

根据放射学发现，赤泥中的活动浓度指数（I）高于OPC，高炉矿渣或粉煤灰中的活动浓度指数。但是，如果（I）值小于1，则所有研究的水合/活化材料都将符合EU指令。尽管如此，这些新材料的使用不仅取决于活性浓度指数，还取决于其理化性质以及必须通过的符合法律要求的质量测试。