2010 NRMCA - National Ready Mixed Concrete Association

feature2010NRMCA QualityBenchmarking SurveyIntroductionThe 2010 NRMCA Quality BenchmarkingSurvey was conducted in the summer of2010. The need for this survey resulted fromdiscussions within the NRMCA ResearchEngineering and Standards Committee andthe survey questions were established by atask group of the committee. Surveys werecompleted by a ready mixed concrete producercompany or division. The survey had3 sections.• Section 1 - General company information• Section 2 - Quality indicators• Section 3 - Quality benchmarksThis report establishes averages and otherbenchmark from this survey. For this surveyrespondents were asked to use data from themost recent fi scal year. Respondents wereasked to avoid guessing and not to respondto questions where information was notavailable. This survey is intended to providebenefits to concrete producers in termsof industry statistics for quality initiatives.There were 28 respondents to this surveyfrom 16 companies. Some large companiessubmitted survey responses for several oftheir divisions.Section 1 - General companyinformation1.3 Annual Concrete Volume(cubic yards)The respondents to this survey produced acumulative 21.7 million cubic yards in 2009representing approximately 8.4% of estimatedready mixed concrete produced inthe U.S. for that year. The breakdown wasas follows:Annual Concrete Volume, Number ofcubic yardsRespondents≤100,000 1100,001 to 250,000 5250,001 to 500,000 6500,001 to 1 Million 121 to 3 Million 2>3 Million 21.4 Number of PlantsThe respondents to this survey supplied concretefrom a total of 670 plants. Company ordivision size ranged from 3 to 179 plants.1.5 Market served by companies – percentof annual productionAll respondedPercent of AnnualMarketProductionPublic (FAA, DOT,city, county) 37Commercial 37Residential 23Other 3Numbers represent the average value. Volumefor the residential market is lower thanexpected due to the overall drop in constructionin that market sector.1.9 Are you in a weathering region requiringair entrained concrete?All respondedPercent ofCold Weather Region RespondentsYes 68%No 32%Section 2 - Quality indicators2.1 Provide information on top 5 sellingmixtures.QuestionAverage2.1a Weighted averagestandard deviation (SD), psi 5052.1b Weighted average Avg.strength, psi* 37732.1c Weighted averagecoefficient of variation,COV, % 10.3%2.1d Average increment, % 28.6%2.1e Number air entrained 2.4*Even though 2.1b asked for averagestrength all respondents provided specifiedstrength. So the number reported is theweighted average specified strength.Weighted average statistics were determinedby multiplying the percent volume of each mixlisted and the individual mix statistic.2.1a and as a result 2.1c had 26 respondents.Other questions were responded to byall 28 respondents. Among the respondentswho answered 2.1a and 2.1c information wasprovided for 90% of the maximum possible130 mixtures. The weighted average SD was505 psi. According to ACI 214R-02, SD of500 to 600 psi would qualify as a good standardof concrete control for general constructiontesting.Average increment represents the incrementof the average strength above the specifiedstrength for the five mixtures reported bythe respondent. On average, the increment ofthe average strength of the mixtures over theaverage specified strength is 28.6% (1079 psi).For mixture submittals according to ACI 318CONCRETE in focus ı 11