<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.2.0.5 -->
<!--Based on XBRL 2.1-->
<!--Created on: 3/26/2026 10:16:39 PM-->
<!--Modified on: 3/26/2026 10:16:39 PM-->
<xsd:schema targetNamespace="http://www.uslm.com/20260501" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:dei="http://xbrl.sec.gov/dei/2025" xmlns:deprecated="http://www.xbrl.org/2009/role/deprecated" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:us-gaap="http://fasb.org/us-gaap/2025" xmlns:utr="http://www.xbrl.org/2009/utr" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:net="http://www.xbrl.org/2009/role/net" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns:attributeFormDefault="unqualified" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:uslm="http://www.uslm.com/20260501" xmlns:ecd="http://xbrl.sec.gov/ecd/2025" xmlns:ecd-sub="http://xbrl.sec.gov/ecd-sub/2025" xmlns:rxp="http://xbrl.sec.gov/rxp/2025" xmlns:snj="http://xbrl.sec.gov/snj/2025">
  <xsd:annotation>
    <xsd:appinfo>
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        <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#PvpDisclosure" roleURI="http://xbrl.sec.gov/ecd/role/PvpDisclosure" xmlns="http://www.xbrl.org/2003/linkbase" />
        <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#AwardTimingDisclosure" roleURI="http://xbrl.sec.gov/ecd/role/AwardTimingDisclosure" xmlns="http://www.xbrl.org/2003/linkbase" />
        <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#InsiderTradingPoliciesProc" roleURI="http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc" xmlns="http://www.xbrl.org/2003/linkbase" />
        <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#PvpAdjustmentsOnly" />
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        <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" />
        <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" />
        <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" />
        <link:arcroleRef arcroleURI="http://www.esma.europa.eu/xbrl/esef/arcrole/wider-narrower" xlink:type="simple" xlink:href="http://www.xbrl.org/lrr/arcrole/esma-arcrole-2018-11-21.xsd#wider-narrower" />
        <presentationLink xlink:role="http://xbrl.sec.gov/dei/role/document/DocumentInformation" xlink:type="extended" xlink:title="995200 - Document - Document Information" xmlns="http://www.xbrl.org/2003/linkbase" />
        <presentationLink xlink:role="http://xbrl.sec.gov/ecd/role/PvpDisclosure" xlink:type="extended" xlink:title="995410 - Disclosure - Pay vs Performance Disclosure" xmlns="http://www.xbrl.org/2003/linkbase" />
        <presentationLink xlink:role="http://xbrl.sec.gov/ecd/role/AwardTimingDisclosure" xlink:type="extended" xlink:title="995443 - Disclosure - Award Timing Disclosure" xmlns="http://www.xbrl.org/2003/linkbase" />
        <presentationLink xlink:role="http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc" xlink:type="extended" xlink:title="995447 - Disclosure - Insider Trading Policies and Procedures" xmlns="http://www.xbrl.org/2003/linkbase" />
        <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="extended" xlink:title="Pay vs Performance Adjustments">
          <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllAdjToCompMember" xlink:label="ecd_AllAdjToCompMember" xlink:title="ecd_AllAdjToCompMember" />
          <link:loc xlink:type="locator" xlink:href="#uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" xlink:label="uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" xlink:title="uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" />
          <link:definitionArc xlink:type="arc" xlink:from="ecd_AllAdjToCompMember" xlink:to="uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllAdjToCompMember To uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" order="2" priority="0" />
          <link:loc xlink:type="locator" xlink:href="#uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" xlink:label="uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" xlink:title="uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" />
          <link:definitionArc xlink:type="arc" xlink:from="ecd_AllAdjToCompMember" xlink:to="uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllAdjToCompMember To uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" order="1" priority="0" />
        </link:definitionLink>
        <link:labelLink xlink:type="extended" xlink:role="http://www.xbrl.org/2003/role/link" />
      </link:linkbase>
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  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd" />
  <xsd:import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd-sub/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-sub-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/rxp/2025" schemaLocation="https://xbrl.sec.gov/rxp/2025/rxp-2025.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/snj/2025" schemaLocation="https://xbrl.sec.gov/snj/2025/snj-2025.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd" />
  <xsd:element name="EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" id="uslm_EquityAwardsAdjustmentsInAggregateChangeInActuarialPresentValueOfAccumulatedBenefitUnderPensionPlansMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" id="uslm_FairValueOfStockAndOptionAwardsForfeitedDuringCoveredYearMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
</xsd:schema>
