Small Strain Shear Modulus Equations for Zeolite–Cement Grouted Sands

Cement production is an energetically demanding process and one of the most important sources of CO 2 emission in the world. Therefore, replacing part of the cement with more environmentally friendly supplementary materials such as natural zeolite ( NZ ) is of great importance. The small strain shear modulus ( G 0 ) of soils is an essential parameter in many aspects of geotechnical engineering. In the present study, ninety-two bender element tests on loose sandy soils grouted with cement and NZ was conducted to obtain equations for predicting the G 0 of grouted sands. Multiple linear regression ( MLR ) and Group Method of Data Handling ( GMDH ) polynomial NN were used to estimate the G 0 of zeolite–cement grouted sands. The G 0 was modeled as a function of the average sand grain size ( D 50 ) as well as the percentages of cement replacement with zeolite ( Z ) and water to cementitious material ratios ( W/CM ) of grout. Also, the parameter active compounds ( AC ) was considered as one of the input parameters instead of the simultaneous effect of W/CM and Z . The results showed that both MLR and GMDH models, in which AC was considered as an input parameter to predict the G 0 of grouted sands, has a much better performance than the same models with W/CM and Z as input parameters. The GMDH -based equations are more efficient than the MLR -based equations. Applying the AC as an input parameter to predict the G 0 of grouted sands by the GMDH models leads to about 35–41% improvement in G 0 prediction. Therefore, the AC is a very effective parameter for estimating the G 0 of the grouted sands. The GMDH -based predicted G 0 is significantly affected by changes in zeolite percentage and the effect of sand particles’ size variation on the accuracy and variation of the predicted G 0 is less than the other two parameters ( W/CM and Z ).