Enhancing stiffness and strength of super-absorbent-polymers-solidified excavated spoils and slurries

液压挖掘机越来越多地用于维修或更换地下基础设施（如水管、下水道、通信电缆等）所需的挖掘。由于其高含水量，水力开挖的垃圾具有类似污泥的稠度，既不能作为固体废物处理，也不能回收利用，也不能作为回填土再利用。处理问题可以通过向废物中添加高吸水性聚合物（sap）来解决。sap可以在水中吸收其自身质量的数百倍，从而使废物“瞬间”凝固，便于作为固体废物处理。为广泛的应用提供基于sap的固化解决方案，包括水力以及传统的挖掘和隧道施工，是行业合作伙伴MetaFLO的核心业务之一。MetaFLO的客户正在寻找使用sap固化的废渣作为修复后关闭挖掘的回填材料的方法。目前，由于缺乏关于其预期岩土特性的信息，sap固化的废物不能用于回填挖掘，必须在固体废物处理场运输和处置。拟议项目的一个关键目标是确定废土固有含水量的阈值，超过该阈值，使用sap固化废土不会产生足够的刚度和强度以允许用作填料或回填体的填料。该项目还将探索将天然土壤与sap固化土混合，以提高土的刚度和强度。该项目的首要目标是制定使用SAPs的指导方针，承包商可以使用这些指导方针来确定土质、SAPs和天然土壤的相对比例，以根据测量的土质固有含水量获得所需的混合土质的岩土技术特性。采用约克最先进的岩土工程实验室设备，提出了一项综合实验室测试计划，其中使用不同含水量的粘土浆料、两种类型的sap和通用波特兰水泥作为粘合剂进行组合，以确定最终混合物的阿特伯格极限、刚度、强度、压实和水力流动特性。

Hydraulic excavators are increasingly being used for excavations needed for repair or replacement of buriedinfrastructure, such as water mains, sewers, communication cables, etc. Because of their high water content,hydraulic excavation spoils have a sludge-like consistency and can neither be disposed off as solid waste norrecycled nor reused as a backfill. The disposal problem can be addressed by adding super-absorbent polymers(SAPs) to the spoils. SAPs can absorb several hundred times their own mass in water, thereby providing"instant" solidification of the spoils and facilitating their disposal as solid waste. Provision of SAP-basedsolidification solutions to a broad range of applications, including spoils from hydraulic as well as traditionalexcavations and tunnelling, is one of the core businesses of the industry partner MetaFLO. MetaFLO's clientsare looking for ways of using SAP-solidified spoils as a backfill material for post-repair closure of excavations.Presently, SAP-solidified spoils cannot be used to backfill excavations because of lack of information on theirexpected geotechnical properties and must be transported and disposed at solid waste disposal sites. A keyobjective of the proposed project is to identify the threshold inherent water content of the spoils above whichthe use of SAPs to solidify the spoils will not result in a fill that is of sufficient stiffness and strength to permitits use as a fill or a backfill. The project will also explore mixing of natural soils with the SAP-solidified spoilsto enhance stiffness and strength of the spoils. The overarching goal of the project is to develop guidelines forthe use of SAPs, which can be used by contractors to establish the relative proportions of spoils, SAPs, andnatural soils to achieve desirable geotechnical properties of the resulting mix based on the measured inherentwater content of the spoils. A comprehensive lab testing program that uses the state-of-the-art geotechnical labtesting facilities at York is proposed in which combinations of clay slurries prepared at different watercontents, two types of SAPs, and general-purpose Portland cement as binding agent are used to ascertainAtterberg limits, stiffness, strength, compaction, and hydraulic flow properties of the resulting mixes.