مهشيد صفي نژاد

Jet grouting is a soil improvement technique that faces environmental challenges, such as cement loss due to the generation of spoil and its subsequent hardening on the ground surface. The collection of this hardened spoil is not only costly but also time-consuming. Spoil consists of a mixture of cement, water, and soil, which can potentially be repurposed for producing widely-used construction materials such as blocks and concrete. In this study, three types of spoil (derived from clayey soil and two types of sandy soil), injection grout, and hardened jet-grouted columns were examined. Cylindrical, cubic, and core samples were collected from the spoil; cylindrical samples were obtained from the grout; and core samples were extracted from the hardened jet-grouted columns. The spoil was pro‎mp‎tly transferred to a block production facility, where blocks were manufactured using varying weight percentages of spoil, pumice or sand, and cement. Additionally, reference blocks from the facility's standard production were collected for compressive strength comparison. Water absorption and density of the blocks were also eva‎luated.The results showed that clayey spoil blocks, with an average compressive strength of 1.12 MPa, did not meet regulatory requirements. However, sandy and gravelly spoil blocks demonstrated average compressive strengths of 2.8 MPa and 3.2 MPa, respectively, indicating that these spoil types, with slight improvements, could be suitable for producing construction blocks. The addition of cement enhanced block strength, with sandy and gravelly spoil cement blocks achieving average compressive strengths of 6.6 MPa and 5 MPa, respectively, meeting standard requirements. Water absorption was higher in blocks containing clay or pumice than in other blocks. Additionally, soil type significantly influenced the compressive strength and density of hardened spoil samples. Sandy spoil samples exhibited greater strength and density compared to clayey spoil, while hardened jet-grouted column samples displayed the highest density. Water absorption in clayey spoil was also higher than in sandy spoil. This study demonstrates that spoil generated from jet grouting, particularly sandy spoil, can be effectively utilized in the production of widely-used construction materials with minor modifications. This approach not only reduces environmental impacts but also prevents cement waste.

پساب , روش تزريق پرفشار , آزمايش تك‌محوري , طرح اختلاط , بلوك خاك سيماني

Spoil , Jet grouting , Uniaxial compression test , Mix design , Cement-soil blocks

Mahshid Safinezhad

Dr Mohsen SaberMahani