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

液压挖掘机越来越多地被用于修复或更换被掩埋的基础设施所需的挖掘工作，如自来水总管、下水道、通讯电缆等。由于液压挖掘废物的含水率高，具有泥浆般的稠度，既不能作为固体废物处置，也不能回收或再用作回填。处理问题可以通过向战利品中添加高吸水性聚合物(SAP)来解决。树液在水中可以吸收几百倍于其自身质量的物质，从而提供战利品的“瞬间”固化，并便于将其作为固体废物处理。为广泛的应用提供基于SAP的固化解决方案，包括液压以及传统挖掘和隧道挖掘产生的矿渣，是行业合作伙伴MetaFlo的核心业务之一。MetaFlo的客户正在寻找将SAP固化的废渣用作挖掘修复后关闭的回填材料的方法。目前，由于缺乏有关预期岩土性质的信息，SAP固化的废渣不能用于回填挖掘，必须在固体废物处置地点运输和处置。拟议项目的一个主要目标是确定战利品的固有含水率门槛，高于该门槛时，使用疏水固化战利品将不会产生具有足够硬度和强度的填充物，从而允许用作填充物或回填物。该项目还将探索将天然土壤与SAP固化残留物混合，以增强残留物的硬度和强度。该项目的总体目标是制定使用汁液的指导方针，承包商可以使用该指南来确定渣土、汁液和天然土壤的相对比例，以根据所测量的渣土的固有含水率来实现所产生的混合料的理想的岩土特性。提出了一个综合的实验室测试计划，该计划利用约克最先进的岩土实验室测试设施，使用不同含水率、两种类型的SAPS和通用波特兰水泥作为粘结剂制备的粘土浆液组合，以确定所得到的混合料的Atterberg极限、刚性、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.